molmass

Molecular mass calculations.

Molmass is a Python library, console script, and web application to calculate the molecular mass (average, nominal, and isotopic pure), the elemental composition, and the mass distribution spectrum of a molecule given by its chemical formula, relative element weights, or sequence.

Calculations are based on the isotopic composition of the elements. Mass deficiency due to chemical bonding is not taken into account.

The library includes a database of physicochemical and descriptive properties of the chemical elements.

Author:

Christoph Gohlke

License:

BSD-3-Clause

Version:

2026.1.8

DOI:

10.5281/zenodo.7135495

Quickstart

Install the molmass package and all dependencies from the Python Package Index:

python -m pip install -U "molmass[all]"

Print the console script usage:

python -m molmass --help

Run the web application:

python -m molmass --web

The molmass library is documented via docstrings.

See Examples for using the programming interface.

Source code and support are available on GitHub.

Requirements

This revision was tested with the following requirements and dependencies (other versions may work):

• CPython 3.11.9, 3.12.10, 3.13.11, 3.14.2

• Flask 3.1.2 (optional)

• Pandas 2.3.3 (optional)

• wxPython 4.2.4 (optional)

Revisions

2026.1.8

• Improve code quality.

2025.12.12

• Make boolean arguments keyword-only (breaking).

2025.11.11

• Allow empty formulas (breaking).

• Derive FormulaError from ValueError.

• Move tests to separate test module.

2025.9.4

• Precompile regex patterns.

• Remove doctest command line option.

• Drop support for Python 3.10, support Python 3.14.

2025.4.14

• Add mass_charge_ratio helper function (#17).

• Drop support for Python 3.9.

2024.10.25

• …

Refer to the CHANGES file for older revisions.

Examples

Calculate the molecular mass, elemental composition, and mass distribution of a molecule from its chemical formula:

>>> from molmass import Formula
>>> f = Formula('C8H10N4O2')  # Caffeine
>>> f
Formula('C8H10N4O2')
>>> f.formula  # hill notation
'C8H10N4O2'
>>> f.empirical
'C4H5N2O'
>>> f.mass  # average mass
194.1909...
>>> f.nominal_mass  # == f.isotope.massnumber
194
>>> f.monoisotopic_mass  # == f.isotope.mass
194.0803...
>>> f.atoms
24
>>> f.charge
0
>>> f.composition().dataframe()
         Count  Relative mass  Fraction
Element...
C            8      96.085920  0.494801
H           10      10.079410  0.051905
N            4      56.026812  0.288514
O            2      31.998810  0.164780
>>> f.spectrum(min_intensity=0.01).dataframe()
             Relative mass  Fraction  Intensity %         m/z
Mass number...
194             194.080376  0.898828   100.000000  194.080376
195             195.082873  0.092625    10.305100  195.082873
196             196.084968  0.008022     0.892492  196.084968
197             197.087214  0.000500     0.055681  197.087214

Access physicochemical and descriptive properties of the chemical elements:

>>> from molmass import ELEMENTS, Element
>>> e = ELEMENTS['C']
>>> e
Element(
    6, 'C', 'Carbon',
    group=14, period=2, block='p', series=1,
    mass=12.01074, eleneg=2.55, eleaffin=1.262118,
    covrad=0.77, atmrad=0.91, vdwrad=1.7,
    tboil=5100.0, tmelt=3825.0, density=3.51,
    eleconfig='[He] 2s2 2p2',
    oxistates='4*, 2, -4*',
    ionenergy=(
        11.2603, 24.383, 47.877, 64.492, 392.077,
        489.981,
    ),
    isotopes={
        12: Isotope(12.0, 0.9893, 12),
        13: Isotope(13.00335483507, 0.0107, 13),
    },
)
>>> e.number
6
>>> e.symbol
'C'
>>> e.name
'Carbon'
>>> e.description
'Carbon is a member of group 14 of the periodic table...'
>>> e.eleconfig
'[He] 2s2 2p2'
>>> e.eleconfig_dict
{(1, 's'): 2, (2, 's'): 2, (2, 'p'): 2}
>>> str(ELEMENTS[6])
'Carbon'
>>> len(ELEMENTS)
109
>>> sum(e.mass for e in ELEMENTS)
14693.181589001...
>>> for e in ELEMENTS:
...     e.validate()
...

License

Copyright (c) 1990-2026, Christoph Gohlke
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

3. Neither the name of the copyright holder nor the names of its
   contributors may be used to endorse or promote products derived from
   this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

molmass module

molmass.__version__ = '2026.1.8'

Molmass version string.

class molmass.Composition(items)

Bases: object

Elemental composition.

The basic interface is an ordered dict[symbol, CompositionItem]].

Parameters:

items (Sequence[tuple[str, int, float, float]]) – Symbol, count, mass, and fraction for all elements in formula. Symbols must not be repeated.

Examples

>>> c = Composition((('2H', 2, 4.028, 0.201), ('O', 1, 15.999, 0.799)))
>>> c
<Composition([('2H', 2, 4.028, 0.201), ...])>
>>> print(c)
Element  Count  Relative mass  Fraction %
2H           2       4.028000     20.1000
O            1      15.999000     79.9000
>>> c['O']
CompositionItem(symbol='O', count=1, mass=15.999, fraction=0.799)

__init__(items)

Parameters:

items (Sequence[tuple[str, int, float, float]])

Return type:

None

property total: CompositionItem

Sums of counts (excluding electrons), masses, and fractions.

>>> Formula('2HO').composition().total
CompositionItem(symbol='Total', count=2, mass=18.0135..., fraction=1.0)

dataframe()

Return composition as pandas DataFrame.

>>> Formula('2HO').composition().dataframe()
         Count  Relative mass  Fraction
Element...
2H           1       2.014102  0.111811
O            1      15.999405  0.888189

Return type:

pandas.DataFrame

asdict()

Return dict[symbol, tuple[symbol, count, mass, fraction]].

>>> Formula('2HO').composition().asdict()
{'2H': (1, 2.0141..., 0.1118...), 'O': (1, 15.9994..., 0.8881...)}

Return type:

dict[str, tuple[int, float, float]]

astuple()

Return tuple[tuple[symbol, count, mass, fraction], …].

>>> Formula('2HO').composition().astuple()
(('2H', 1, 2.0141..., 0.1118...), ('O', 1, 15.9994..., 0.8881...))

Return type:

tuple[tuple[str, int, float, float], …]

keys()

Return iterator of symbols.

Return type:

Iterator[str]

values()

Return iterator of CompositionItems.

Return type:

Iterator[CompositionItem]

items()

Return iterator of (symbol, CompositionItem) pairs.

Return type:

Iterator[tuple[str, CompositionItem]]

__repr__()

Return repr(self).

Return type:

str

__str__()

Return str(self).

Return type:

str

__weakref__

list of weak references to the object

class molmass.CompositionItem(symbol, count, mass, fraction)

Bases: object

Item of elemental composition.

Parameters:

• symbol (str)

• count (int)

• mass (float)

• fraction (float)

symbol: str

Chemical symbol of element or electron.

count: int

Number of elements or electrons in composition.

mass: float

Relative mass.

fraction: float

Mass fraction.

astuple()

Return (symbol, count, mass, fraction).

Return type:

tuple[str, int, float, float]

__eq__(other)

Return self==value.

__init__(symbol, count, mass, fraction)

Parameters:

• symbol (str)

• count (int)

• mass (float)

• fraction (float)

Return type:

None

__repr__()

Return repr(self).

__weakref__

list of weak references to the object

class molmass.Element(number, symbol, name, group, period, block, series, mass, eleneg, eleaffin, covrad, atmrad, vdwrad, tboil, tmelt, density, eleconfig, oxistates, ionenergy, isotopes)

Bases: object

Chemical element.

Parameters:

• number (int)

• symbol (str)

• name (str)

• group (int)

• period (int)

• block (str)

• series (int)

• mass (float)

• eleneg (float)

• eleaffin (float)

• covrad (float)

• atmrad (float)

• vdwrad (float)

• tboil (float)

• tmelt (float)

• density (float)

• eleconfig (str)

• oxistates (str)

• ionenergy (tuple[float, ...])

• isotopes (dict[int, Isotope])

number: int

Atomic number of protons.

symbol: str

Chemical symbol.

name: str

English name.

group: int

Group in periodic table.

period: int

Period in periodic table.

block: str

Block in periodic table.

series: int

Index to chemical series.

mass: float

Relative atomic mass.

The ratio of the average mass of atoms of the element to 1/12 of the mass of an atom of 12C.

eleneg: float

Electronegativity on Pauling scale.

eleaffin: float

Electron affinity in eV.

covrad: float

Covalent radius in angstrom.

atmrad: float

Atomic radius in angstrom.

vdwrad: float

Van der Waals radius in angstrom.

tboil: float

Boiling temperature in K.

tmelt: float

Melting temperature in K.

density: float

Density at 295K in g/cm3 respectively g/L.

eleconfig: str

Ground state electron configuration.

oxistates: str

Oxidation states.

ionenergy: tuple[float, ...]

Ionization energies in eV.

isotopes: dict[int, Isotope]

Isotopic composition.

Mapping of isotope mass number to relative atomic mass and abundance.

property protons: int

Number of protons.

property electrons: int

Number of electrons.

property neutrons: int

Number of neutrons in most abundant natural stable isotope.

property nominalmass: int

Mass number of most abundant natural stable isotope.

property exactmass: float

Relative atomic mass calculated from isotopic composition.

property eleconfig_dict: dict[tuple[int, str], int]

electrons.

Type:

Ground state electron configuration (shell, subshell)

property eleshells: tuple[int, ...]

Number of electrons in shell.

property description: str

Text description of element.

validate()

Check consistency of data. Raise ValueError on failure.

Return type:

None

__repr__()

Return repr(self).

Return type:

str

__str__()

Return str(self).

Return type:

str

__eq__(other)

Return self==value.

__init__(number, symbol, name, group, period, block, series, mass, eleneg, eleaffin, covrad, atmrad, vdwrad, tboil, tmelt, density, eleconfig, oxistates, ionenergy, isotopes)

Parameters:

• number (int)

• symbol (str)

• name (str)

• group (int)

• period (int)

• block (str)

• series (int)

• mass (float)

• eleneg (float)

• eleaffin (float)

• covrad (float)

• atmrad (float)

• vdwrad (float)

• tboil (float)

• tmelt (float)

• density (float)

• eleconfig (str)

• oxistates (str)

• ionenergy (tuple[float, ...])

• isotopes (dict[int, Isotope])

Return type:

None

__weakref__

list of weak references to the object

class molmass.Formula(formula='', /, groups=None, *, parse_groups=True, parse_oligos=True, parse_fractions=True, parse_arithmetic=True, allow_empty=True)

Bases: object

Chemical formula.

Calculate various properties from formula string, such as hill notation, empirical formula, mass, elemental composition, and mass distribution.

Parameters:

• formula (str) – Chemical formula. May contain only symbols of chemical elements, groups, isotopes, parentheses, numbers, and trailing charge. The formula is not validated until it is parsed on demand during instance attribute access or method calls.

• groups (dict[str, str] | None) – Mapping of chemical group name to formula in Hill notation. The default is GROUPS.

• parse_groups (bool) – Parse chemical group names. Enabled by default.

• parse_oligos (bool) – Parse pure peptide and nucleotide sequences. Enabled by default.

• parse_fractions (bool) – Parse list of mass fractions. Enabled by default.

• parse_arithmetic (bool) – Parse simple arithmetic operators. Enabled by default.

• allow_empty (bool) – If False, raise FormulaError for empty formulas. Enabled by default.

Examples

Elements and counts:

>>> Formula('')
Formula('')

>>> Formula('H2O')
Formula('H2O')

Isotopes:

>>> Formula('D2O')
Formula('[2H]2O')

>>> Formula('[30Si]3O2')
Formula('[30Si]3O2')

Ion charges:

>>> Formula('[AsO4]3-')
Formula('[AsO4]3-')

>>> Formula('O2-2')
Formula('[O2]2-')

Abbreviations of chemical groups:

>>> Formula('EtOH')
Formula('(C2H5)OH')

Simple arithmetic:

>>> Formula('(COOH)2')
Formula('(COOH)2')

>>> Formula('CuSO4.5H2O')
Formula('CuSO4(H2O)5')

Relative element weights:

>>> Formula('O: 0.26, 30Si: 0.74')
Formula('O2[30Si]3')

Nucleotide sequences:

>>> Formula('CGCGAATTCGCG')
Formula('((C10H12N5O5P)2(C9H12N3O6P)4(C10H12N5O6P)4(C10H13N2O7P)2H2O)')

>>> Formula('dsrna(CCUU)')
Formula('((C10H12N5O6P)2(C9H12N3O7P)2...(C9H11N2O8P)2(H2O)2)')

Peptide sequences:

>>> Formula('MDRGEQGLLK')
Formula('((C4H5NO3)(C5H7NO3)(C2H3NO)2...(C6H12N4O)H2O)')

>>> Formula('peptide(CPK)')
Formula('((C3H5NOS)(C6H12N2O)(C5H7NO)H2O)')

__init__(formula='', /, groups=None, *, parse_groups=True, parse_oligos=True, parse_fractions=True, parse_arithmetic=True, allow_empty=True)

Parameters:

• formula (str)

• groups (dict[str, str] | None)

• parse_groups (bool)

• parse_oligos (bool)

• parse_fractions (bool)

• parse_arithmetic (bool)

• allow_empty (bool)

Return type:

None

property _elements: dict[str, dict[int, int]]

Number of atoms and isotopes by element.

A dict[symbol: dict[massnumber: count]], where massnumber is either an isotope mass number or zero for a natural distribution of isotopes.

Raises FormulaError if formula is invalid.

>>> Formula('H')._elements
{'H': {0: 1}}
>>> Formula('[2H]2O')._elements
{'O': {0: 1}, 'H': {2: 2}}

property formula: str

Formula string in Hill notation.

>>> Formula('BrC2H5').formula
'C2H5Br'
>>> Formula('[(CH3)3Si2]2NNa').formula
'C6H18NNaSi4'

property empirical: str

Empirical formula in Hill notation.

The empirical formula has the simplest whole number ratio of atoms of each element present in the formula.

>>> Formula('H2O').empirical
'H2O'
>>> Formula('C6H12O6').empirical
'CH2O'
>>> Formula('[SO4]2_4-').empirical
'[O4S]2-'

property expanded: str

Formula string with expanded groups, charges, and sequences.

The input formula parsed by from_string().

>>> Formula('WQ').expanded  # peptide sequence
'((C5H8N2O2)(C11H10N2O)H2O)'

property atoms: int

Number of atoms.

>>> Formula('CH3COOH').atoms
8

property charge: int

Charge number in units of elementary charge.

>>> Formula('SO4_2-').charge
-2

property gcd: int

Greatest common divisor of element counts.

>>> Formula('H2').gcd
2
>>> Formula('H2O').gcd
1
>>> Formula('C6H12O6').gcd
6

property mass: float

Average relative molecular mass.

The sum of the relative atomic masses of all atoms and charges in the formula. Equals the molar mass in g/mol, that is, the mass of one mole of substance.

>>> Formula('H').mass
1.007941
>>> Formula('H+').mass
1.007392...
>>> Formula('SO4_2-').mass
96.06351...
>>> Formula('12C').mass
12.0
>>> Formula('C8H10N4O2').mass
194.1909...
>>> Formula('C48H32AgCuO12P2Ru4').mass
1438.404...

property monoisotopic_mass: float

Mass of isotope composed of most abundant elemental isotopes.

>>> Formula('C8H10N4O2').monoisotopic_mass
194.08037...

property nominal_mass: int

Monoisotopic mass number.

The number of protons and neutrons in the isotope composed of the most abundant elemental isotopes.

>>> Formula('C8H10N4O2').nominal_mass
194

property mz: float

Mass-to-charge ratio.

Using the average relative molecular mass.

>>> Formula('H').mz
1.007941
>>> Formula('H+').mz
1.007392...
>>> Formula('SO4_2-').mz
48.03175...

property isotope: Isotope

Isotope composed of most abundant elemental isotopes.

>>> Formula('C').isotope.mass
12.0
>>> Formula('13C').isotope.massnumber
13
>>> Formula('C48H32AgCuO12P2Ru4').isotope
Isotope(mass=1439.588..., abundance=0.00205..., massnumber=1440...)

composition(*, isotopic=True)

Return elemental composition.

Parameters:

isotopic (bool) – List isotopes separately as opposed to part of an element.

Return type:

Composition

Examples

>>> print(Formula('[12C][13C]C').composition())
Element  Count  Relative mass  Fraction %
C            1      12.010740     32.4491
12C          1      12.000000     32.4201
13C          1      13.003355     35.1308

>>> print(Formula('[12C][13C]C').composition(isotopic=False))
Element  Count  Relative mass  Fraction %
C            3      37.014095    100.0000

spectrum(*, min_fraction=1e-16, min_intensity=None)

Return low resolution mass spectrum.

Calculated by combining the mass numbers of the elemental isotopes.

Parameters:

• min_fraction (float) – Minimum of fraction to return.

• min_intensity (float | None) – Minimum intensity to return.

Returns:

Mapping of massnumber to mass, fraction, and intensity.

Return type:

Spectrum

Examples

>>> print(Formula('D').spectrum())
A  Relative mass  Fraction %  Intensity %
2      2.0141018  100.000000   100.000000

>>> print(Formula('H').spectrum())
A  Relative mass  Fraction %  Intensity %
1      1.0078250   99.988500   100.000000
2      2.0141018    0.011500     0.011501

>>> print(Formula('H+').spectrum())
A  Relative mass  Fraction %  Intensity %
1      1.0072765   99.988500   100.000000
2      2.0135532    0.011500     0.011501

>>> print(Formula('D2').spectrum())
A  Relative mass  Fraction %  Intensity %
4      4.0282036  100.000000   100.000000

>>> print(Formula('DH').spectrum())
A  Relative mass  Fraction %  Intensity %
3      3.0219268   99.988500   100.000000
4      4.0282036    0.011500     0.011501

>>> print(Formula('H2').spectrum())
A  Relative mass  Fraction %  Intensity %
2      2.0156501   99.977001   100.000000
3      3.0219268    0.022997     0.023003
4      4.0282036    0.000001     0.000001

>>> print(Formula('DHO').spectrum())
A   Relative mass  Fraction %  Intensity %
19      19.016841   99.745528   100.000000
20      20.021536    0.049468     0.049594
21      21.021087    0.204981     0.205504
22      22.027363    0.000024     0.000024

>>> print(Formula('SO4_2-').spectrum(min_intensity=0.1))
A   Relative mass  Fraction %  Intensity %  m/z
96      95.952827   94.070057   100.000000  47.976413
97      96.952996    0.886071     0.941927  48.476498
98      97.949936    4.983307     5.297443  48.974968

__mul__(number, /)

Return formula repeated number times.

>>> Formula('HO-') * 2
Formula('[(HO)2]2-')

Parameters:

number (int)

Return type:

Formula

__rmul__(number, /)

Return formula repeated number times.

>>> 2 * Formula('H2O')
Formula('(H2O)2')

Parameters:

number (int)

Return type:

Formula

__add__(other, /)

Add this and other formula.

>>> Formula('H2O') + Formula('HO-')
Formula('[(H2O)(HO)]-')

Parameters:

other (Formula)

Return type:

Formula

__sub__(other, /)

Subtract elements of other formula.

>>> Formula('H2O') - Formula('O')
Formula('H2')

Parameters:

other (Formula)

Return type:

Formula

__str__()

Return str(self).

Return type:

str

__repr__()

Return repr(self).

Return type:

str

__weakref__

list of weak references to the object

class molmass.FormulaError(message, formula='', position=-1)

Bases: ValueError

Error in chemical formula.

Parameters:

• message (str) – Error message.

• formula (str) – Chemical formula in which error occurred.

• position (int) – Position in formula where error occurred.

Examples

>>> Formula('abc').formula
Traceback (most recent call last):
 ...
molmass.molmass.FormulaError: unexpected character 'a'
abc
^

>>> Formula('(H2O)2-H2O').formula
Traceback (most recent call last):
 ...
molmass.molmass.FormulaError: subtraction not allowed
(H2O)2-H2O
......^

>>> Formula('[11C]').formula
Traceback (most recent call last):
 ...
molmass.molmass.FormulaError: unknown isotope '11C'
[11C]
.^

__init__(message, formula='', position=-1)

Parameters:

• message (str)

• formula (str)

• position (int)

Return type:

None

position: int

Position in formula where error occurred.

message: str

Error message.

formula: str

Formula in which error occurred.

__str__()

Return str(self).

Return type:

str

__weakref__

list of weak references to the object

class molmass.Isotope(mass, abundance, massnumber, charge=0)

Bases: object

Isotope properties.

Parameters:

• mass (float)

• abundance (float)

• massnumber (int)

• charge (int)

mass: float

Monoisotopic mass.

abundance: float

Natural fraction on Earth.

massnumber: int

Number of protons and neutrons.

charge: int = 0

Net charge in units of elementary charge.

property mz: float

Mass-to-charge ratio.

__eq__(other)

Return self==value.

__init__(mass, abundance, massnumber, charge=0)

Parameters:

• mass (float)

• abundance (float)

• massnumber (int)

• charge (int)

Return type:

None

__repr__()

Return repr(self).

__weakref__

list of weak references to the object

class molmass.Particle(name, mass, charge)

Bases: object

Particle, e.g., electron, proton, or neutron.

Parameters:

• name (str)

• mass (float)

• charge (float)

name: str

English name.

__eq__(other)

Return self==value.

__init__(name, mass, charge)

Parameters:

• name (str)

• mass (float)

• charge (float)

Return type:

None

__repr__()

Return repr(self).

__weakref__

list of weak references to the object

mass: float

Relative mass.

The ratio of the average mass of atoms of the particle to 1/12 of the mass of an atom of 12C.

charge: float

Electric charge in coulomb.

__str__()

Return str(self).

Return type:

str

class molmass.Spectrum(spectrum, /, charge=0)

Bases: object

Mass distribution.

The basic interface is a sorted dict[massnumber, SpectrumEntry].

Parameters:

• spectrum (dict[int, list[float]]) – Mapping of mass number to relative mass and fraction.

• charge (int) – Charge number.

Examples

>>> s = Spectrum({1: [1.078, 0.9999], 2: [2.014, 0.0001]})
>>> s
<Spectrum({1: [1, 1.078, 0.9999, 100.0, 1.078], ...})>
>>> print(s)
A  Relative mass  Fraction %  Intensity %
1      1.0780000   99.990000   100.000000
2      2.0140000    0.010000     0.010001
>>> s[2]
SpectrumEntry(massnumber=2, mass=2.014, fraction=0.0001, ..., mz=2.014)

__init__(spectrum, /, charge=0)

Parameters:

• spectrum (dict[int, list[float]])

• charge (int)

Return type:

None

property peak: SpectrumEntry

Most abundant entry.

Raise ValueError if spectrum is empty.

>>> Formula('C8H10N4O2').spectrum().peak.mass
194.0803...

property mean: float

Mean of all masses.

>>> Formula('C8H10N4O2').spectrum().mean
194.1909...

property range: tuple[int, int]

Smallest and largest massnumbers.

Raise ValueError if spectrum is empty.

>>> Formula('C8H10N4O2').spectrum().range
(194, 205)

dataframe()

Return composition as pandas DataFrame.

>>> Formula('SO4_2-').spectrum(min_intensity=0.1).dataframe()
             Relative mass  Fraction  Intensity %        m/z
Mass number...
96               95.952827  0.940701   100.000000  47.976413
97               96.952996  0.008861     0.941927  48.476498
98               97.949936  0.049833     5.297443  48.974968

Return type:

pandas.DataFrame

asdict()

Return dict[massnumber, tuple[mass, fraction, intensity, mz]].

>>> Formula('DH').spectrum().asdict()
{3: (3.0..., 0.9..., 100.0, 3...), 4: (4.0..., 0.0..., 0.0..., 4...)}

Return type:

dict[int, tuple[float, float, float, float]]

astuple()

Return tuple[tuple[massnumber, mass, fraction, intensity, mz], …].

>>> Formula('DH').spectrum().astuple()
((3, 3.0..., 0.9..., 100.0, 3...), (4, 4.0..., 0.0..., 0.0..., 4...))

Return type:

tuple[tuple[int, float, float, float, float], …]

keys()

Return iterator of massnumbers.

Return type:

Iterator[int]

values()

Return iterator of SpectrumEntry objects.

Return type:

Iterator[SpectrumEntry]

items()

Return iterator of (massnumber, SpectrumEntry) pairs.

Return type:

Iterator[tuple[int, SpectrumEntry]]

__repr__()

Return repr(self).

Return type:

str

__str__()

Return str(self).

Return type:

str

__weakref__

list of weak references to the object

class molmass.SpectrumEntry(massnumber, mass, fraction, intensity, mz)

Bases: object

Entry of mass distribution spectrum.

Parameters:

• massnumber (int)

• mass (float)

• fraction (float)

• intensity (float)

• mz (float)

massnumber: int

Mass number, bin of spectrum.

mass: float

Relative mass.

fraction: float

Mass fraction or abundance.

intensity: float

Fraction normalized by maximum fraction in %.

mz: float

Mass-to-charge ratio.

astuple()

Return attributes (massnumber, mass, fraction, intensity, mz).

Return type:

tuple[int, float, float, float, float]

__eq__(other)

Return self==value.

__init__(massnumber, mass, fraction, intensity, mz)

Parameters:

• massnumber (int)

• mass (float)

• fraction (float)

• intensity (float)

• mz (float)

Return type:

None

__repr__()

Return repr(self).

__weakref__

list of weak references to the object

molmass.analyze(formula, /, *, maxatoms=512, min_intensity=1e-4, debug=False)

Return analysis of chemical formula as string.

Parameters:

• formula (str) – Chemical formula.

• maxatoms (int) – Number of atoms below which to calculate spectrum.

• min_intensity (float) – Minimum intensity to include in spectrum.

• debug (bool) – If True, raise exceptions, else print error message.

Return type:

str

Examples

>>> print(analyze('C8H10N4O2', min_intensity=0.01))
Formula: C8H10N4O2
Empirical formula: C4H5N2O

Nominal mass: 194
Average mass: 194.19095
Monoisotopic mass: 194.08038 (89.883%)
Most abundant mass: 194.08038 (89.883%)
Mean of distribution: 194.18604

Number of atoms: 24

Elemental Composition

Element  Count  Relative mass  Fraction %
C            8       96.08592     49.4801
H           10       10.07941      5.1905
N            4       56.02681     28.8514
O            2       31.99881     16.4780

Mass Distribution

A    Relative mass  Fraction %  Intensity %
194      194.08038   89.882781   100.000000
195      195.08287    9.262511    10.305100
196      196.08497    0.802196     0.892492
197      197.08721    0.050048     0.055681

molmass.format_charge(charge, prefix='', /)

Return string representation of charge.

Parameters:

• charge (int) – Charge number.

• prefix (str) – Character placed in front of charge in case abs(charge)>1.

Return type:

str

Examples

>>> format_charge(-2, '_')
'_2-'
>>> format_charge(1, '_')
'+'

molmass.from_elements(elements, /, *, divisor=1, charge=0, fmt=None)

Return formula string in Hill notation from elements dict.

Parameters:

• elements (dict[str, dict[int, int]]) – Number of atoms and isotopes by element. See Formula._elements().

• divisor (int) – Number by which to divide element counts and charge.

• charge (int) – Charge number.

• fmt (tuple[str, str, str, str] | None) – Format strings.

Return type:

str

Examples

>>> from_elements({'C': {0: 4, 12: 2}}, divisor=2)
'C2[12C]'

>>> from_elements(
...     {'C': {0: 4, 12: 2}},
...     divisor=2,
...     fmt=(
...         '{}',
...         '{}<sub>{}</sub>',
...         '<sup>{}</sup>{}',
...         '<sup>{}</sup>{}<sub>{}</sub>',
...     ),
... )
'C<sub>2</sub><sup>12</sup>C'

molmass.from_fractions(fractions, /, *, maxcount=10, precision=1e-4)

Return formula string from elemental mass fractions.

Parameters:

• fractions (dict[str, float]) – Mapping of element symbols to abundances.

• maxcount (int) – Maximum count of single element in formula.

• precision (float) – Threshold for finding smallest acceptable element count.

Return type:

str

Examples

>>> from_fractions({'H': 0.112, 'O': 0.888})
'H2O'
>>> from_fractions({'D': 0.2, 'O': 0.8})
'O[2H]2'
>>> from_fractions({'H': 8.97, 'C': 59.39, 'O': 31.64})
'C5H9O2'
>>> from_fractions({'O': 0.26, '30Si': 0.74})
'O2[30Si]3'

molmass.from_oligo(sequence, dtype='ssdna', /)

Return chemical formula for polymer of unmodified (deoxy)nucleotides.

Each strand includes a 5’ monophosphate.

Parameters:

• sequence (str) – DNA or RNA sequence.

• dtype (str) – Nucleic acid sequence type. One of ‘ssdna’, ‘dsdna’, ‘ssrna’, or ‘dsrna’.

Return type:

str

Examples

>>> from_oligo('AC', 'ssdna')
'((C10H12N5O5P)(C9H12N3O6P)H2O)'

>>> from_oligo('AU', 'dsrna')
'((C10H12N5O6P)2(C9H11N2O8P)2(H2O)2)'

>>> f = Formula(from_oligo('ATC G', 'dsdna'))
>>> print(f.formula, f.atoms, f.mass)
C78H102N30O50P8 268 2507.60913...

>>> f = Formula(from_oligo('AUC G_2+', 'ssrna'))
>>> print(f.formula, f.atoms, f.mass)
[C38H49N15O29P4]2+ 135 1303.7744...

molmass.from_peptide(sequence, /)

Return chemical formula for polymer of unmodified amino acids.

Parameters:

sequence (str) – Peptide sequence.

Return type:

str

Examples

>>> from_peptide('GG')
'((C2H3NO)2H2O)'

>>> f = Formula(from_peptide('GPAVL IMCFY WHKRQ NEDST_2+'))
>>> print(f.formula, f.atoms, f.mass)
[C107H159N29O30S2]2+ 327 2395.7168...

molmass.from_sequence(sequence, groups, /)

Return sequence as chemical formula.

Parameters:

• sequence (str) – DNA, RNA, or peptide sequence.

• groups (dict[str, str]) – Mapping of sequence item to chemical formula in Hill notation. One of DEOXYNUCLEOTIDES, NUCLEOTIDES, or AMINOACIDS.

Return type:

str

Examples

>>> from_sequence('A', {'A': 'B'})
'(B)'
>>> from_sequence('AA', {'A': 'B'})
'(B)2'

molmass.from_string(formula, /, groups=None, *, parse_groups=True, parse_oligos=True, parse_fractions=True, parse_arithmetic=True)

Return formula string from user input string.

Parameters:

• formula (str) – Chemical formula. Supports simple, non-nested arithmetic (+ and *), abbreviations of common chemical groups, peptides, oligos, and mass fractions.

• groups (dict[str, str] | None) – Mapping of chemical group name to formula in Hill notation. The default is GROUPS.

• parse_groups (bool) – Parse chemical group names.

• parse_oligos (bool) – Parse pure peptide and nucleotide sequences.

• parse_fractions (bool) – Parse list of mass fractions.

• parse_arithmetic (bool) – Parse simple arithmetic operators.

Returns:

Chemical formula composed only of element and isotope symbols, parentheses, numbers, and trailing ion charges.

Raises:

• FormulaError – Invalid formula.

• TypeError – Non-string formula.

Return type:

str

Examples

>>> from_string('Valohp')
'(C5H8NO2)'
>>> from_string('Valohp', parse_groups=False)
'Valohp'
>>> from_string('HLeu2OH')
'H(C6H11NO)2OH'
>>> from_string('D2O')
'[2H]2O'
>>> from_string('O: 0.26, 30Si: 0.74')
'O2[30Si]3'
>>> from_string('O: 0.26, 30Si: 0.74', parse_fractions=False)
'O:0(,30Si:0)26()74'
>>> from_string('PhNH2.HCl')
'(C6H5)NH2HCl'
>>> from_string('PhNH2.HCl', parse_arithmetic=False)
'(C6H5)NH2.HCl'
>>> from_string('CuSO4.5H2O')
'CuSO4(H2O)5'
>>> from_string('CuSO4+5*H2O')
'CuSO4(H2O)5'
>>> from_string('5*H2O')
'(H2O)5'
>>> from_string('O2+12C')  # not [12C]O2
'O2(C)12'
>>> from_string('ssdna(AC)')
'((C10H12N5O5P)(C9H12N3O6P)H2O)'
>>> from_string('peptide(GG)')
'((C2H3NO)2H2O)'
>>> from_string('WQ')
'((C5H8N2O2)(C11H10N2O)H2O)'
>>> from_string('WQ', parse_oligos=False)
'WQ'

molmass.hill_sorted(symbols, /)

Return iterator over element symbols in order of Hill notation.

Parameters:

symbols (Iterable[str]) – Element symbols.

Yields:

Element symbols in order of Hill notation.

Return type:

Iterator[str]

Examples

>>> tuple(hill_sorted('HCO'))
('C', 'H', 'O')

molmass.join_charge(formula, charge, separator='', /)

Return formula with charge appended.

Parameters:

• formula (str) – Chemical formula without charge.

• charge (int) – Charge number.

• separator (str) – Character separating formula from charge. One of ‘’ or ‘_’.

Returns:

Formula with charge != 0 appended. If separator is empty, the formula is wrapped in square brackets.

Return type:

str

Examples

>>> join_charge('Formula', 0)
'Formula'
>>> join_charge('Formula', 1)
'[Formula]+'
>>> join_charge('Formula', 2)
'[Formula]2+'
>>> join_charge('Formula', -2, '_')
'Formula_2-'

molmass.main(argv=None, /)

Command line usage main function.

Parameters:

argv (list[str] | None) – Command line arguments.

Return type:

int

molmass.mass_charge_ratio(mass, charge, /)

Return mass-to-charge ratio.

Parameters:

• mass (float) – Mass to divide by charge.

• charge (int) – Charge number in units of elementary charge.

Return type:

float

Examples

>>> mass_charge_ratio(1.0, -2)
0.5
>>> mass_charge_ratio(1.0, 1)
1.0
>>> mass_charge_ratio(1.0, 0)
1.0
>>> f = Formula('SO4_2-')
>>> mass_charge_ratio(f.monoisotopic_mass, f.charge)
47.976...

molmass.split_charge(formula, /)

Return formula stripped from charge, and charge.

Parameters:

formula (str) – Chemical formula with appended charge.

Returns:

Chemical formula without charge, and charge number.

Return type:

tuple[str, int]

Examples

>>> split_charge('Formula')
('Formula', 0)
>>> split_charge('Formula+')
('Formula', 1)
>>> split_charge('Formula+1')
('Formula', 1)
>>> split_charge('Formula++')
('Formula', 2)
>>> split_charge('[Formula]2+')
('Formula', 2)
>>> split_charge('Formula+2')
('Formula', 2)
>>> split_charge('[[Formula]]2-')
('[Formula]', -2)
>>> split_charge('[Formula]-2')
('Formula', -2)
>>> split_charge('[Formula]_2-')
('Formula', -2)
>>> split_charge('Formula_2-')
('Formula', -2)
>>> split_charge('Formula-2')
('Formula', -2)
>>> split_charge('Formula_+')
('Formula', 1)
>>> split_charge('Formula+-')
('Formula', 0)
>>> split_charge('Formul+a+')
('Formul+a', 1)

molmass.AMINOACIDS

molmass.DEOXYNUCLEOTIDES

molmass.ELECTRON = Particle(name='Electron', mass=0.000548579909065, charge=-1.602176634e-19)

Electron particle.

molmass.ELEMENTARY_CHARGE = 1.602176634e-19

Elementary charge in coulombs.

molmass.ELEMENTS = Elements(     Element(         1, 'H', 'Hydrogen',         group=1, period=1, block='s', series=1,         mass=1.007941, eleneg=2.2, eleaffin=0.75420375,         covrad=0.32, atmrad=0.79, vdwrad=1.2,         tboil=20.28, tmelt=13.81, density=0.084,         eleconfig='1s',         oxistates='1*, -1',         ionenergy=(13.5984,),         isotopes={             1: Isotope(1.00782503223, 0.999885, 1),             2: Isotope(2.01410177812, 0.000115, 2),         },     ),     Element(         2, 'He', 'Helium',         group=18, period=1, block='s', series=2,         mass=4.002602, eleneg=0.0, eleaffin=0.0,         covrad=0.93, atmrad=0.49, vdwrad=1.4,         tboil=4.216, tmelt=0.95, density=0.1785,         eleconfig='1s2',         oxistates='*',         ionenergy=(24.5874, 54.416),         isotopes={             3: Isotope(3.0160293201, 1.34e-06, 3),             4: Isotope(4.00260325413, 0.99999866, 4),         },     ),     Element(         3, 'Li', 'Lithium',         group=1, period=2, block='s', series=3,         mass=6.94, eleneg=0.98, eleaffin=0.618049,         covrad=1.23, atmrad=2.05, vdwrad=1.82,         tboil=1615.0, tmelt=453.7, density=0.53,         eleconfig='[He] 2s',         oxistates='1*',         ionenergy=(5.3917, 75.638, 122.451),         isotopes={             6: Isotope(6.0151228874, 0.0759, 6),             7: Isotope(7.0160034366, 0.9241, 7),         },     ),     Element(         4, 'Be', 'Beryllium',         group=2, period=2, block='s', series=4,         mass=9.0121831, eleneg=1.57, eleaffin=0.0,         covrad=0.9, atmrad=1.4, vdwrad=0.0,         tboil=3243.0, tmelt=1560.0, density=1.85,         eleconfig='[He] 2s2',         oxistates='2*',         ionenergy=(9.3227, 18.211, 153.893, 217.713),         isotopes={9: Isotope(9.012183065, 1.0, 9)},     ),     Element(         5, 'B', 'Boron',         group=13, period=2, block='p', series=5,         mass=10.811, eleneg=2.04, eleaffin=0.279723,         covrad=0.82, atmrad=1.17, vdwrad=0.0,         tboil=4275.0, tmelt=2365.0, density=2.46,         eleconfig='[He] 2s2 2p',         oxistates='3*',         ionenergy=(8.298, 25.154, 37.93, 59.368, 340.217),         isotopes={             10: Isotope(10.01293695, 0.199, 10),             11: Isotope(11.00930536, 0.801, 11),         },     ),     Element(         6, 'C', 'Carbon',         group=14, period=2, block='p', series=1,         mass=12.01074, eleneg=2.55, eleaffin=1.262118,         covrad=0.77, atmrad=0.91, vdwrad=1.7,         tboil=5100.0, tmelt=3825.0, density=3.51,         eleconfig='[He] 2s2 2p2',         oxistates='4*, 2, -4*',         ionenergy=(             11.2603, 24.383, 47.877, 64.492, 392.077,             489.981,         ),         isotopes={             12: Isotope(12.0, 0.9893, 12),             13: Isotope(13.00335483507, 0.0107, 13),         },     ),     Element(         7, 'N', 'Nitrogen',         group=15, period=2, block='p', series=1,         mass=14.006703, eleneg=3.04, eleaffin=-0.07,         covrad=0.75, atmrad=0.75, vdwrad=1.55,         tboil=77.344, tmelt=63.15, density=1.17,         eleconfig='[He] 2s2 2p3',         oxistates='5, 4, 3, 2, -3*',         ionenergy=(             14.5341, 39.601, 47.488, 77.472, 97.888,             522.057, 667.029,         ),         isotopes={             14: Isotope(14.00307400443, 0.99636, 14),             15: Isotope(15.00010889888, 0.00364, 15),         },     ),     Element(         8, 'O', 'Oxygen',         group=16, period=2, block='p', series=1,         mass=15.999405, eleneg=3.44, eleaffin=1.461112,         covrad=0.73, atmrad=0.65, vdwrad=1.52,         tboil=90.188, tmelt=54.8, density=1.33,         eleconfig='[He] 2s2 2p4',         oxistates='-2*, -1',         ionenergy=(             13.6181, 35.116, 54.934, 77.412, 113.896,             138.116, 739.315, 871.387,         ),         isotopes={             16: Isotope(15.99491461957, 0.99757, 16),             17: Isotope(16.9991317565, 0.00038, 17),             18: Isotope(17.99915961286, 0.00205, 18),         },     ),     Element(         9, 'F', 'Fluorine',         group=17, period=2, block='p', series=6,         mass=18.998403163, eleneg=3.98, eleaffin=3.4011887,         covrad=0.72, atmrad=0.57, vdwrad=1.47,         tboil=85.0, tmelt=53.55, density=1.58,         eleconfig='[He] 2s2 2p5',         oxistates='-1*',         ionenergy=(             17.4228, 34.97, 62.707, 87.138, 114.24,             157.161, 185.182, 953.886, 1103.089,         ),         isotopes={19: Isotope(18.99840316273, 1.0, 19)},     ),     Element(         10, 'Ne', 'Neon',         group=18, period=2, block='p', series=2,         mass=20.1797, eleneg=0.0, eleaffin=0.0,         covrad=0.71, atmrad=0.51, vdwrad=1.54,         tboil=27.1, tmelt=24.55, density=0.8999,         eleconfig='[He] 2s2 2p6',         oxistates='*',         ionenergy=(             21.5645, 40.962, 63.45, 97.11, 126.21,             157.93, 207.27, 239.09, 1195.797, 1362.164,         ),         isotopes={             20: Isotope(19.9924401762, 0.9048, 20),             21: Isotope(20.993846685, 0.0027, 21),             22: Isotope(21.991385114, 0.0925, 22),         },     ),     Element(         11, 'Na', 'Sodium',         group=1, period=3, block='s', series=3,         mass=22.98976928, eleneg=0.93, eleaffin=0.547926,         covrad=1.54, atmrad=2.23, vdwrad=2.27,         tboil=1156.0, tmelt=371.0, density=0.97,         eleconfig='[Ne] 3s',         oxistates='1*',         ionenergy=(             5.1391, 47.286, 71.64, 98.91, 138.39,             172.15, 208.47, 264.18, 299.87, 1465.091,             1648.659,         ),         isotopes={23: Isotope(22.989769282, 1.0, 23)},     ),     Element(         12, 'Mg', 'Magnesium',         group=2, period=3, block='s', series=4,         mass=24.3051, eleneg=1.31, eleaffin=0.0,         covrad=1.36, atmrad=1.72, vdwrad=1.73,         tboil=1380.0, tmelt=922.0, density=1.74,         eleconfig='[Ne] 3s2',         oxistates='2*',         ionenergy=(             7.6462, 15.035, 80.143, 109.24, 141.26,             186.5, 224.94, 265.9, 327.95, 367.53,             1761.802, 1962.613,         ),         isotopes={             24: Isotope(23.985041697, 0.7899, 24),             25: Isotope(24.985836976, 0.1, 25),             26: Isotope(25.982592968, 0.1101, 26),         },     ),     Element(         13, 'Al', 'Aluminium',         group=13, period=3, block='p', series=7,         mass=26.9815385, eleneg=1.61, eleaffin=0.43283,         covrad=1.18, atmrad=1.82, vdwrad=0.0,         tboil=2740.0, tmelt=933.5, density=2.7,         eleconfig='[Ne] 3s2 3p',         oxistates='3*',         ionenergy=(             5.9858, 18.828, 28.447, 119.99, 153.71,             190.47, 241.43, 284.59, 330.21, 398.57,             442.07, 2085.983, 2304.08,         ),         isotopes={27: Isotope(26.98153853, 1.0, 27)},     ),     Element(         14, 'Si', 'Silicon',         group=14, period=3, block='p', series=5,         mass=28.0855, eleneg=1.9, eleaffin=1.389521,         covrad=1.11, atmrad=1.46, vdwrad=2.1,         tboil=2630.0, tmelt=1683.0, density=2.33,         eleconfig='[Ne] 3s2 3p2',         oxistates='4*, -4',         ionenergy=(             8.1517, 16.345, 33.492, 45.141, 166.77,             205.05, 246.52, 303.17, 351.1, 401.43,             476.06, 523.5, 2437.676, 2673.108,         ),         isotopes={             28: Isotope(27.97692653465, 0.92223, 28),             29: Isotope(28.9764946649, 0.04685, 29),             30: Isotope(29.973770136, 0.03092, 30),         },     ),     Element(         15, 'P', 'Phosphorus',         group=15, period=3, block='p', series=1,         mass=30.973761998, eleneg=2.19, eleaffin=0.7465,         covrad=1.06, atmrad=1.23, vdwrad=1.8,         tboil=553.0, tmelt=317.3, density=1.82,         eleconfig='[Ne] 3s2 3p3',         oxistates='5*, 3, -3',         ionenergy=(             10.4867, 19.725, 30.18, 51.37, 65.023,             220.43, 263.22, 309.41, 371.73, 424.5,             479.57, 560.41, 611.85, 2816.943, 3069.762,         ),         isotopes={31: Isotope(30.97376199842, 1.0, 31)},     ),     Element(         16, 'S', 'Sulfur',         group=16, period=3, block='p', series=1,         mass=32.0648, eleneg=2.58, eleaffin=2.0771029,         covrad=1.02, atmrad=1.09, vdwrad=1.8,         tboil=717.82, tmelt=392.2, density=2.06,         eleconfig='[Ne] 3s2 3p4',         oxistates='6*, 4, 2, -2',         ionenergy=(             10.36, 23.33, 34.83, 47.3, 72.68,             88.049, 280.93, 328.23, 379.1, 447.09,             504.78, 564.65, 651.63, 707.14, 3223.836,             3494.099,         ),         isotopes={             32: Isotope(31.9720711744, 0.9499, 32),             33: Isotope(32.9714589098, 0.0075, 33),             34: Isotope(33.967867004, 0.0425, 34),             36: Isotope(35.96708071, 0.0001, 36),         },     ),     Element(         17, 'Cl', 'Chlorine',         group=17, period=3, block='p', series=6,         mass=35.4529, eleneg=3.16, eleaffin=3.612724,         covrad=0.99, atmrad=0.97, vdwrad=1.75,         tboil=239.18, tmelt=172.17, density=2.95,         eleconfig='[Ne] 3s2 3p5',         oxistates='7, 5, 3, 1, -1*',         ionenergy=(             12.9676, 23.81, 39.61, 53.46, 67.8,             98.03, 114.193, 348.28, 400.05, 455.62,             529.97, 591.97, 656.69, 749.75, 809.39,             3658.425, 3946.193,         ),         isotopes={             35: Isotope(34.968852682, 0.7576, 35),             37: Isotope(36.965902602, 0.2424, 37),         },     ),     Element(         18, 'Ar', 'Argon',         group=18, period=3, block='p', series=2,         mass=39.948, eleneg=0.0, eleaffin=0.0,         covrad=0.98, atmrad=0.88, vdwrad=1.88,         tboil=87.45, tmelt=83.95, density=1.66,         eleconfig='[Ne] 3s2 3p6',         oxistates='*',         ionenergy=(             15.7596, 27.629, 40.74, 59.81, 75.02,             91.007, 124.319, 143.456, 422.44, 478.68,             538.95, 618.24, 686.09, 755.73, 854.75,             918.0, 4120.778, 4426.114,         ),         isotopes={             36: Isotope(35.967545105, 0.003336, 36),             38: Isotope(37.96273211, 0.000629, 38),             40: Isotope(39.9623831237, 0.996035, 40),         },     ),     Element(         19, 'K', 'Potassium',         group=1, period=4, block='s', series=3,         mass=39.0983, eleneg=0.82, eleaffin=0.501459,         covrad=2.03, atmrad=2.77, vdwrad=2.75,         tboil=1033.0, tmelt=336.8, density=0.86,         eleconfig='[Ar] 4s',         oxistates='1*',         ionenergy=(             4.3407, 31.625, 45.72, 60.91, 82.66,             100.0, 117.56, 154.86, 175.814, 503.44,             564.13, 629.09, 714.02, 787.13, 861.77,             968.0, 1034.0, 4610.955, 4933.931,         ),         isotopes={             39: Isotope(38.9637064864, 0.932581, 39),             40: Isotope(39.963998166, 0.000117, 40),             41: Isotope(40.9618252579, 0.067302, 41),         },     ),     Element(         20, 'Ca', 'Calcium',         group=2, period=4, block='s', series=4,         mass=40.078, eleneg=1.0, eleaffin=0.02455,         covrad=1.74, atmrad=2.23, vdwrad=0.0,         tboil=1757.0, tmelt=1112.0, density=1.54,         eleconfig='[Ar] 4s2',         oxistates='2*',         ionenergy=(             6.1132, 11.71, 50.908, 67.1, 84.41,             108.78, 127.7, 147.24, 188.54, 211.27,             591.25, 656.39, 726.03, 816.61, 895.12,             974.0, 1087.0, 1157.0, 5129.045, 5469.738,         ),         isotopes={             40: Isotope(39.962590863, 0.96941, 40),             42: Isotope(41.95861783, 0.00647, 42),             43: Isotope(42.95876644, 0.00135, 43),             44: Isotope(43.95548156, 0.02086, 44),             46: Isotope(45.953689, 4e-05, 46),             48: Isotope(47.95252276, 0.00187, 48),         },     ),     Element(         21, 'Sc', 'Scandium',         group=3, period=4, block='d', series=8,         mass=44.955908, eleneg=1.36, eleaffin=0.188,         covrad=1.44, atmrad=2.09, vdwrad=0.0,         tboil=3109.0, tmelt=1814.0, density=2.99,         eleconfig='[Ar] 3d 4s2',         oxistates='3*',         ionenergy=(             6.5615, 12.8, 24.76, 73.47, 91.66,             110.1, 138.0, 158.7, 180.02, 225.32,             249.8, 685.89, 755.47, 829.79, 926.0,         ),         isotopes={45: Isotope(44.95590828, 1.0, 45)},     ),     Element(         22, 'Ti', 'Titanium',         group=4, period=4, block='d', series=8,         mass=47.867, eleneg=1.54, eleaffin=0.084,         covrad=1.32, atmrad=2.0, vdwrad=0.0,         tboil=3560.0, tmelt=1935.0, density=4.51,         eleconfig='[Ar] 3d2 4s2',         oxistates='4*, 3',         ionenergy=(             6.8281, 13.58, 27.491, 43.266, 99.22,             119.36, 140.8, 168.5, 193.5, 215.91,             265.23, 291.497, 787.33, 861.33,         ),         isotopes={             46: Isotope(45.95262772, 0.0825, 46),             47: Isotope(46.95175879, 0.0744, 47),             48: Isotope(47.94794198, 0.7372, 48),             49: Isotope(48.94786568, 0.0541, 49),             50: Isotope(49.94478689, 0.0518, 50),         },     ),     Element(         23, 'V', 'Vanadium',         group=5, period=4, block='d', series=8,         mass=50.9415, eleneg=1.63, eleaffin=0.525,         covrad=1.22, atmrad=1.92, vdwrad=0.0,         tboil=3650.0, tmelt=2163.0, density=6.09,         eleconfig='[Ar] 3d3 4s2',         oxistates='5*, 4, 3, 2, 0',         ionenergy=(             6.7462, 14.65, 29.31, 46.707, 65.23,             128.12, 150.17, 173.7, 205.8, 230.5,             255.04, 308.25, 336.267, 895.58, 974.02,         ),         isotopes={             50: Isotope(49.94715601, 0.0025, 50),             51: Isotope(50.94395704, 0.9975, 51),         },     ),     Element(         24, 'Cr', 'Chromium',         group=6, period=4, block='d', series=8,         mass=51.9961, eleneg=1.66, eleaffin=0.67584,         covrad=1.18, atmrad=1.85, vdwrad=0.0,         tboil=2945.0, tmelt=2130.0, density=7.14,         eleconfig='[Ar] 3d5 4s',         oxistates='6, 3*, 2, 0',         ionenergy=(             6.7665, 16.5, 30.96, 49.1, 69.3,             90.56, 161.1, 184.7, 209.3, 244.4,             270.8, 298.0, 355.0, 384.3, 1010.64,         ),         isotopes={             50: Isotope(49.94604183, 0.04345, 50),             52: Isotope(51.94050623, 0.83789, 52),             53: Isotope(52.94064815, 0.09501, 53),             54: Isotope(53.93887916, 0.02365, 54),         },     ),     Element(         25, 'Mn', 'Manganese',         group=7, period=4, block='d', series=8,         mass=54.938044, eleneg=1.55, eleaffin=0.0,         covrad=1.17, atmrad=1.79, vdwrad=0.0,         tboil=2235.0, tmelt=1518.0, density=7.44,         eleconfig='[Ar] 3d5 4s2',         oxistates='7, 6, 4, 3, 2*, 0, -1',         ionenergy=(             7.434, 15.64, 33.667, 51.2, 72.4,             95.0, 119.27, 196.46, 221.8, 248.3,             286.0, 314.4, 343.6, 404.0, 435.3,             1136.2,         ),         isotopes={55: Isotope(54.93804391, 1.0, 55)},     ),     Element(         26, 'Fe', 'Iron',         group=8, period=4, block='d', series=8,         mass=55.845, eleneg=1.83, eleaffin=0.151,         covrad=1.17, atmrad=1.72, vdwrad=0.0,         tboil=3023.0, tmelt=1808.0, density=7.874,         eleconfig='[Ar] 3d6 4s2',         oxistates='6, 3*, 2, 0, -2',         ionenergy=(             7.9024, 16.18, 30.651, 54.8, 75.0,             99.0, 125.0, 151.06, 235.04, 262.1,             290.4, 330.8, 361.0, 392.2, 457.0,             485.5, 1266.1,         ),         isotopes={             54: Isotope(53.93960899, 0.05845, 54),             56: Isotope(55.93493633, 0.91754, 56),             57: Isotope(56.93539284, 0.02119, 57),             58: Isotope(57.93327443, 0.00282, 58),         },     ),     Element(         27, 'Co', 'Cobalt',         group=9, period=4, block='d', series=8,         mass=58.933194, eleneg=1.88, eleaffin=0.6633,         covrad=1.16, atmrad=1.67, vdwrad=0.0,         tboil=3143.0, tmelt=1768.0, density=8.89,         eleconfig='[Ar] 3d7 4s2',         oxistates='3, 2*, 0, -1',         ionenergy=(             7.881, 17.06, 33.5, 51.3, 79.5,             102.0, 129.0, 157.0, 186.13, 276.0,             305.0, 336.0, 376.0, 411.0, 444.0,             512.0, 546.8, 1403.0,         ),         isotopes={59: Isotope(58.93319429, 1.0, 59)},     ),     Element(         28, 'Ni', 'Nickel',         group=10, period=4, block='d', series=8,         mass=58.6934, eleneg=1.91, eleaffin=1.15716,         covrad=1.15, atmrad=1.62, vdwrad=1.63,         tboil=3005.0, tmelt=1726.0, density=8.91,         eleconfig='[Ar] 3d8 4s2',         oxistates='3, 2*, 0',         ionenergy=(             7.6398, 18.168, 35.17, 54.9, 75.5,             108.0, 133.0, 162.0, 193.0, 224.5,             321.2, 352.0, 384.0, 430.0, 464.0,             499.0, 571.0, 607.2, 1547.0,         ),         isotopes={             58: Isotope(57.93534241, 0.68077, 58),             60: Isotope(59.93078588, 0.26223, 60),             61: Isotope(60.93105557, 0.011399, 61),             62: Isotope(61.92834537, 0.036346, 62),             64: Isotope(63.92796682, 0.009255, 64),         },     ),     Element(         29, 'Cu', 'Copper',         group=11, period=4, block='d', series=8,         mass=63.546, eleneg=1.9, eleaffin=1.23578,         covrad=1.17, atmrad=1.57, vdwrad=1.4,         tboil=2840.0, tmelt=1356.6, density=8.92,         eleconfig='[Ar] 3d10 4s',         oxistates='2*, 1',         ionenergy=(             7.7264, 20.292, 26.83, 55.2, 79.9,             103.0, 139.0, 166.0, 199.0, 232.0,             266.0, 368.8, 401.0, 435.0, 484.0,             520.0, 557.0, 633.0, 671.0, 1698.0,         ),         isotopes={             63: Isotope(62.92959772, 0.6915, 63),             65: Isotope(64.9277897, 0.3085, 65),         },     ),     Element(         30, 'Zn', 'Zinc',         group=12, period=4, block='d', series=8,         mass=65.38, eleneg=1.65, eleaffin=0.0,         covrad=1.25, atmrad=1.53, vdwrad=1.39,         tboil=1180.0, tmelt=692.73, density=7.14,         eleconfig='[Ar] 3d10 4s2',         oxistates='2*',         ionenergy=(             9.3942, 17.964, 39.722, 59.4, 82.6,             108.0, 134.0, 174.0, 203.0, 238.0,             274.0, 310.8, 419.7, 454.0, 490.0,             542.0, 579.0, 619.0, 698.8, 738.0,             1856.0,         ),         isotopes={             64: Isotope(63.92914201, 0.4917, 64),             66: Isotope(65.92603381, 0.2773, 66),             67: Isotope(66.92712775, 0.0404, 67),             68: Isotope(67.92484455, 0.1845, 68),             70: Isotope(69.9253192, 0.0061, 70),         },     ),     Element(         31, 'Ga', 'Gallium',         group=13, period=4, block='p', series=7,         mass=69.723, eleneg=1.81, eleaffin=0.41,         covrad=1.26, atmrad=1.81, vdwrad=1.87,         tboil=2478.0, tmelt=302.92, density=5.91,         eleconfig='[Ar] 3d10 4s2 4p',         oxistates='3*',         ionenergy=(5.9993, 20.51, 30.71, 64.0),         isotopes={             69: Isotope(68.9255735, 0.60108, 69),             71: Isotope(70.92470258, 0.39892, 71),         },     ),     Element(         32, 'Ge', 'Germanium',         group=14, period=4, block='p', series=5,         mass=72.63, eleneg=2.01, eleaffin=1.232712,         covrad=1.22, atmrad=1.52, vdwrad=0.0,         tboil=3107.0, tmelt=1211.5, density=5.32,         eleconfig='[Ar] 3d10 4s2 4p2',         oxistates='4*',         ionenergy=(7.8994, 15.934, 34.22, 45.71, 93.5),         isotopes={             70: Isotope(69.92424875, 0.2057, 70),             72: Isotope(71.922075826, 0.2745, 72),             73: Isotope(72.923458956, 0.0775, 73),             74: Isotope(73.921177761, 0.365, 74),             76: Isotope(75.921402726, 0.0773, 76),         },     ),     Element(         33, 'As', 'Arsenic',         group=15, period=4, block='p', series=5,         mass=74.921595, eleneg=2.18, eleaffin=0.814,         covrad=1.2, atmrad=1.33, vdwrad=1.85,         tboil=876.0, tmelt=1090.0, density=5.72,         eleconfig='[Ar] 3d10 4s2 4p3',         oxistates='5, 3*, -3',         ionenergy=(             9.7886, 18.633, 28.351, 50.13, 62.63,             127.6,         ),         isotopes={75: Isotope(74.92159457, 1.0, 75)},     ),     Element(         34, 'Se', 'Selenium',         group=16, period=4, block='p', series=1,         mass=78.971, eleneg=2.55, eleaffin=2.02067,         covrad=1.16, atmrad=1.22, vdwrad=1.9,         tboil=958.0, tmelt=494.0, density=4.82,         eleconfig='[Ar] 3d10 4s2 4p4',         oxistates='6, 4*, -2',         ionenergy=(             9.7524, 21.9, 30.82, 42.944, 68.3,             81.7, 155.4,         ),         isotopes={             74: Isotope(73.922475934, 0.0089, 74),             76: Isotope(75.919213704, 0.0937, 76),             77: Isotope(76.919914154, 0.0763, 77),             78: Isotope(77.91730928, 0.2377, 78),             80: Isotope(79.9165218, 0.4961, 80),             82: Isotope(81.9166995, 0.0873, 82),         },     ),     Element(         35, 'Br', 'Bromine',         group=17, period=4, block='p', series=6,         mass=79.9035, eleneg=2.96, eleaffin=3.363588,         covrad=1.14, atmrad=1.12, vdwrad=1.85,         tboil=331.85, tmelt=265.95, density=3.14,         eleconfig='[Ar] 3d10 4s2 4p5',         oxistates='7, 5, 3, 1, -1*',         ionenergy=(             11.8138, 21.8, 36.0, 47.3, 59.7,             88.6, 103.0, 192.8,         ),         isotopes={             79: Isotope(78.9183376, 0.5069, 79),             81: Isotope(80.9162897, 0.4931, 81),         },     ),     Element(         36, 'Kr', 'Krypton',         group=18, period=4, block='p', series=2,         mass=83.798, eleneg=0.0, eleaffin=0.0,         covrad=1.12, atmrad=1.03, vdwrad=2.02,         tboil=120.85, tmelt=116.0, density=4.48,         eleconfig='[Ar] 3d10 4s2 4p6',         oxistates='2*',         ionenergy=(             13.9996, 24.359, 36.95, 52.5, 64.7,             78.5, 110.0, 126.0, 230.39,         ),         isotopes={             78: Isotope(77.92036494, 0.00355, 78),             80: Isotope(79.91637808, 0.02286, 80),             82: Isotope(81.91348273, 0.11593, 82),             83: Isotope(82.91412716, 0.115, 83),             84: Isotope(83.9114977282, 0.56987, 84),             86: Isotope(85.9106106269, 0.17279, 86),         },     ),     Element(         37, 'Rb', 'Rubidium',         group=1, period=5, block='s', series=3,         mass=85.4678, eleneg=0.82, eleaffin=0.485916,         covrad=2.16, atmrad=2.98, vdwrad=0.0,         tboil=961.0, tmelt=312.63, density=1.53,         eleconfig='[Kr] 5s',         oxistates='1*',         ionenergy=(             4.1771, 27.28, 40.0, 52.6, 71.0,             84.4, 99.2, 136.0, 150.0, 277.1,         ),         isotopes={             85: Isotope(84.9117897379, 0.7217, 85),             87: Isotope(86.909180531, 0.2783, 87),         },     ),     Element(         38, 'Sr', 'Strontium',         group=2, period=5, block='s', series=4,         mass=87.62, eleneg=0.95, eleaffin=0.05206,         covrad=1.91, atmrad=2.45, vdwrad=0.0,         tboil=1655.0, tmelt=1042.0, density=2.63,         eleconfig='[Kr] 5s2',         oxistates='2*',         ionenergy=(             5.6949, 11.03, 43.6, 57.0, 71.6,             90.8, 106.0, 122.3, 162.0, 177.0,             324.1,         ),         isotopes={             84: Isotope(83.9134191, 0.0056, 84),             86: Isotope(85.9092606, 0.0986, 86),             87: Isotope(86.9088775, 0.07, 87),             88: Isotope(87.9056125, 0.8258, 88),         },     ),     Element(         39, 'Y', 'Yttrium',         group=3, period=5, block='d', series=8,         mass=88.90584, eleneg=1.22, eleaffin=0.307,         covrad=1.62, atmrad=2.27, vdwrad=0.0,         tboil=3611.0, tmelt=1795.0, density=4.47,         eleconfig='[Kr] 4d 5s2',         oxistates='3*',         ionenergy=(             6.2173, 12.24, 20.52, 61.8, 77.0,             93.0, 116.0, 129.0, 146.52, 191.0,             206.0, 374.0,         ),         isotopes={89: Isotope(88.9058403, 1.0, 89)},     ),     Element(         40, 'Zr', 'Zirconium',         group=4, period=5, block='d', series=8,         mass=91.224, eleneg=1.33, eleaffin=0.426,         covrad=1.45, atmrad=2.16, vdwrad=0.0,         tboil=4682.0, tmelt=2128.0, density=6.51,         eleconfig='[Kr] 4d2 5s2',         oxistates='4*',         ionenergy=(6.6339, 13.13, 22.99, 34.34, 81.5),         isotopes={             90: Isotope(89.9046977, 0.5145, 90),             91: Isotope(90.9056396, 0.1122, 91),             92: Isotope(91.9050347, 0.1715, 92),             94: Isotope(93.9063108, 0.1738, 94),             96: Isotope(95.9082714, 0.028, 96),         },     ),     Element(         41, 'Nb', 'Niobium',         group=5, period=5, block='d', series=8,         mass=92.90637, eleneg=1.6, eleaffin=0.893,         covrad=1.34, atmrad=2.08, vdwrad=0.0,         tboil=5015.0, tmelt=2742.0, density=8.58,         eleconfig='[Kr] 4d4 5s',         oxistates='5*, 3',         ionenergy=(             6.7589, 14.32, 25.04, 38.3, 50.55,             102.6, 125.0,         ),         isotopes={93: Isotope(92.906373, 1.0, 93)},     ),     Element(         42, 'Mo', 'Molybdenum',         group=6, period=5, block='d', series=8,         mass=95.95, eleneg=2.16, eleaffin=0.7472,         covrad=1.3, atmrad=2.01, vdwrad=0.0,         tboil=4912.0, tmelt=2896.0, density=10.28,         eleconfig='[Kr] 4d5 5s',         oxistates='6*, 5, 4, 3, 2, 0',         ionenergy=(             7.0924, 16.15, 27.16, 46.4, 61.2,             68.0, 126.8, 153.0,         ),         isotopes={             92: Isotope(91.90680796, 0.1453, 92),             94: Isotope(93.9050849, 0.0915, 94),             95: Isotope(94.90583877, 0.1584, 95),             96: Isotope(95.90467612, 0.1667, 96),             97: Isotope(96.90601812, 0.096, 97),             98: Isotope(97.90540482, 0.2439, 98),             100: Isotope(99.9074718, 0.0982, 100),         },     ),     Element(         43, 'Tc', 'Technetium',         group=7, period=5, block='d', series=8,         mass=97.9072, eleneg=1.9, eleaffin=0.55,         covrad=1.27, atmrad=1.95, vdwrad=0.0,         tboil=4538.0, tmelt=2477.0, density=11.49,         eleconfig='[Kr] 4d5 5s2',         oxistates='7*',         ionenergy=(7.28, 15.26, 29.54),         isotopes={98: Isotope(97.9072124, 1.0, 98)},     ),     Element(         44, 'Ru', 'Ruthenium',         group=8, period=5, block='d', series=8,         mass=101.07, eleneg=2.2, eleaffin=1.04638,         covrad=1.25, atmrad=1.89, vdwrad=0.0,         tboil=4425.0, tmelt=2610.0, density=12.45,         eleconfig='[Kr] 4d7 5s',         oxistates='8, 6, 4*, 3*, 2, 0, -2',         ionenergy=(7.3605, 16.76, 28.47),         isotopes={             96: Isotope(95.90759025, 0.0554, 96),             98: Isotope(97.9052868, 0.0187, 98),             99: Isotope(98.9059341, 0.1276, 99),             100: Isotope(99.9042143, 0.126, 100),             101: Isotope(100.9055769, 0.1706, 101),             102: Isotope(101.9043441, 0.3155, 102),             104: Isotope(103.9054275, 0.1862, 104),         },     ),     Element(         45, 'Rh', 'Rhodium',         group=9, period=5, block='d', series=8,         mass=102.9055, eleneg=2.28, eleaffin=1.14289,         covrad=1.25, atmrad=1.83, vdwrad=0.0,         tboil=3970.0, tmelt=2236.0, density=12.41,         eleconfig='[Kr] 4d8 5s',         oxistates='5, 4, 3*, 1*, 2, 0',         ionenergy=(7.4589, 18.08, 31.06),         isotopes={103: Isotope(102.905498, 1.0, 103)},     ),     Element(         46, 'Pd', 'Palladium',         group=10, period=5, block='d', series=8,         mass=106.42, eleneg=2.2, eleaffin=0.56214,         covrad=1.28, atmrad=1.79, vdwrad=1.63,         tboil=3240.0, tmelt=1825.0, density=12.02,         eleconfig='[Kr] 4d10',         oxistates='4, 2*, 0',         ionenergy=(8.3369, 19.43, 32.93),         isotopes={             102: Isotope(101.9056022, 0.0102, 102),             104: Isotope(103.9040305, 0.1114, 104),             105: Isotope(104.9050796, 0.2233, 105),             106: Isotope(105.9034804, 0.2733, 106),             108: Isotope(107.9038916, 0.2646, 108),             110: Isotope(109.9051722, 0.1172, 110),         },     ),     Element(         47, 'Ag', 'Silver',         group=11, period=5, block='d', series=8,         mass=107.8682, eleneg=1.93, eleaffin=1.30447,         covrad=1.34, atmrad=1.75, vdwrad=1.72,         tboil=2436.0, tmelt=1235.1, density=10.49,         eleconfig='[Kr] 4d10 5s',         oxistates='2, 1*',         ionenergy=(7.5762, 21.49, 34.83),         isotopes={             107: Isotope(106.9050916, 0.51839, 107),             109: Isotope(108.9047553, 0.48161, 109),         },     ),     Element(         48, 'Cd', 'Cadmium',         group=12, period=5, block='d', series=8,         mass=112.414, eleneg=1.69, eleaffin=0.0,         covrad=1.48, atmrad=1.71, vdwrad=1.58,         tboil=1040.0, tmelt=594.26, density=8.64,         eleconfig='[Kr] 4d10 5s2',         oxistates='2*',         ionenergy=(8.9938, 16.908, 37.48),         isotopes={             106: Isotope(105.9064599, 0.0125, 106),             108: Isotope(107.9041834, 0.0089, 108),             110: Isotope(109.90300661, 0.1249, 110),             111: Isotope(110.90418287, 0.128, 111),             112: Isotope(111.90276287, 0.2413, 112),             113: Isotope(112.90440813, 0.1222, 113),             114: Isotope(113.90336509, 0.2873, 114),             116: Isotope(115.90476315, 0.0749, 116),         },     ),     Element(         49, 'In', 'Indium',         group=13, period=5, block='p', series=7,         mass=114.818, eleneg=1.78, eleaffin=0.404,         covrad=1.44, atmrad=2.0, vdwrad=1.93,         tboil=2350.0, tmelt=429.78, density=7.31,         eleconfig='[Kr] 4d10 5s2 5p',         oxistates='3*',         ionenergy=(5.7864, 18.869, 28.03, 55.45),         isotopes={             113: Isotope(112.90406184, 0.0429, 113),             115: Isotope(114.903878776, 0.9571, 115),         },     ),     Element(         50, 'Sn', 'Tin',         group=14, period=5, block='p', series=7,         mass=118.71, eleneg=1.96, eleaffin=1.112066,         covrad=1.41, atmrad=1.72, vdwrad=2.17,         tboil=2876.0, tmelt=505.12, density=7.29,         eleconfig='[Kr] 4d10 5s2 5p2',         oxistates='4*, 2*',         ionenergy=(7.3439, 14.632, 30.502, 40.734, 72.28),         isotopes={             112: Isotope(111.90482387, 0.0097, 112),             114: Isotope(113.9027827, 0.0066, 114),             115: Isotope(114.903344699, 0.0034, 115),             116: Isotope(115.9017428, 0.1454, 116),             117: Isotope(116.90295398, 0.0768, 117),             118: Isotope(117.90160657, 0.2422, 118),             119: Isotope(118.90331117, 0.0859, 119),             120: Isotope(119.90220163, 0.3258, 120),             122: Isotope(121.9034438, 0.0463, 122),             124: Isotope(123.9052766, 0.0579, 124),         },     ),     Element(         51, 'Sb', 'Antimony',         group=15, period=5, block='p', series=5,         mass=121.76, eleneg=2.05, eleaffin=1.047401,         covrad=1.4, atmrad=1.53, vdwrad=0.0,         tboil=1860.0, tmelt=903.91, density=6.69,         eleconfig='[Kr] 4d10 5s2 5p3',         oxistates='5, 3*, -3',         ionenergy=(             8.6084, 16.53, 25.3, 44.2, 56.0,             108.0,         ),         isotopes={             121: Isotope(120.903812, 0.5721, 121),             123: Isotope(122.9042132, 0.4279, 123),         },     ),     Element(         52, 'Te', 'Tellurium',         group=16, period=5, block='p', series=5,         mass=127.6, eleneg=2.1, eleaffin=1.970875,         covrad=1.36, atmrad=1.42, vdwrad=2.06,         tboil=1261.0, tmelt=722.72, density=6.25,         eleconfig='[Kr] 4d10 5s2 5p4',         oxistates='6, 4*, -2',         ionenergy=(             9.0096, 18.6, 27.96, 37.41, 58.75,             70.7, 137.0,         ),         isotopes={             120: Isotope(119.9040593, 0.0009, 120),             122: Isotope(121.9030435, 0.0255, 122),             123: Isotope(122.9042698, 0.0089, 123),             124: Isotope(123.9028171, 0.0474, 124),             125: Isotope(124.9044299, 0.0707, 125),             126: Isotope(125.9033109, 0.1884, 126),             128: Isotope(127.90446128, 0.3174, 128),             130: Isotope(129.906222748, 0.3408, 130),         },     ),     Element(         53, 'I', 'Iodine',         group=17, period=5, block='p', series=6,         mass=126.90447, eleneg=2.66, eleaffin=3.059038,         covrad=1.33, atmrad=1.32, vdwrad=1.98,         tboil=457.5, tmelt=386.7, density=4.94,         eleconfig='[Kr] 4d10 5s2 5p5',         oxistates='7, 5, 1, -1*',         ionenergy=(10.4513, 19.131, 33.0),         isotopes={127: Isotope(126.9044719, 1.0, 127)},     ),     Element(         54, 'Xe', 'Xenon',         group=18, period=5, block='p', series=2,         mass=131.293, eleneg=0.0, eleaffin=0.0,         covrad=1.31, atmrad=1.24, vdwrad=2.16,         tboil=165.1, tmelt=161.39, density=4.49,         eleconfig='[Kr] 4d10 5s2 5p6',         oxistates='2, 4, 6',         ionenergy=(12.1298, 21.21, 32.1),         isotopes={             124: Isotope(123.905892, 0.000952, 124),             126: Isotope(125.9042983, 0.00089, 126),             128: Isotope(127.903531, 0.019102, 128),             129: Isotope(128.9047808611, 0.264006, 129),             130: Isotope(129.903509349, 0.04071, 130),             131: Isotope(130.90508406, 0.212324, 131),             132: Isotope(131.9041550856, 0.269086, 132),             134: Isotope(133.90539466, 0.104357, 134),             136: Isotope(135.907214484, 0.088573, 136),         },     ),     Element(         55, 'Cs', 'Caesium',         group=1, period=6, block='s', series=3,         mass=132.90545196, eleneg=0.79, eleaffin=0.471626,         covrad=2.35, atmrad=3.34, vdwrad=0.0,         tboil=944.0, tmelt=301.54, density=1.9,         eleconfig='[Xe] 6s',         oxistates='1*',         ionenergy=(3.8939, 25.1),         isotopes={133: Isotope(132.905451961, 1.0, 133)},     ),     Element(         56, 'Ba', 'Barium',         group=2, period=6, block='s', series=4,         mass=137.327, eleneg=0.89, eleaffin=0.14462,         covrad=1.98, atmrad=2.78, vdwrad=0.0,         tboil=2078.0, tmelt=1002.0, density=3.65,         eleconfig='[Xe] 6s2',         oxistates='2*',         ionenergy=(5.2117, 100.004),         isotopes={             130: Isotope(129.9063207, 0.00106, 130),             132: Isotope(131.9050611, 0.00101, 132),             134: Isotope(133.90450818, 0.02417, 134),             135: Isotope(134.90568838, 0.06592, 135),             136: Isotope(135.90457573, 0.07854, 136),             137: Isotope(136.90582714, 0.11232, 137),             138: Isotope(137.905247, 0.71698, 138),         },     ),     Element(         57, 'La', 'Lanthanum',         group=3, period=6, block='f', series=9,         mass=138.90547, eleneg=1.1, eleaffin=0.47,         covrad=1.69, atmrad=2.74, vdwrad=0.0,         tboil=3737.0, tmelt=1191.0, density=6.16,         eleconfig='[Xe] 5d 6s2',         oxistates='3*',         ionenergy=(5.5769, 11.06, 19.175),         isotopes={             138: Isotope(137.9071149, 0.0008881, 138),             139: Isotope(138.9063563, 0.9991119, 139),         },     ),     Element(         58, 'Ce', 'Cerium',         group=3, period=6, block='f', series=9,         mass=140.116, eleneg=1.12, eleaffin=0.5,         covrad=1.65, atmrad=2.7, vdwrad=0.0,         tboil=3715.0, tmelt=1071.0, density=6.77,         eleconfig='[Xe] 4f 5d 6s2',         oxistates='4, 3*',         ionenergy=(5.5387, 10.85, 20.2, 36.72),         isotopes={             136: Isotope(135.90712921, 0.00185, 136),             138: Isotope(137.905991, 0.00251, 138),             140: Isotope(139.9054431, 0.8845, 140),             142: Isotope(141.9092504, 0.11114, 142),         },     ),     Element(         59, 'Pr', 'Praseodymium',         group=3, period=6, block='f', series=9,         mass=140.90766, eleneg=1.13, eleaffin=0.5,         covrad=1.65, atmrad=2.67, vdwrad=0.0,         tboil=3785.0, tmelt=1204.0, density=6.48,         eleconfig='[Xe] 4f3 6s2',         oxistates='4, 3*',         ionenergy=(5.473, 10.55, 21.62, 38.95, 57.45),         isotopes={141: Isotope(140.9076576, 1.0, 141)},     ),     Element(         60, 'Nd', 'Neodymium',         group=3, period=6, block='f', series=9,         mass=144.242, eleneg=1.14, eleaffin=0.5,         covrad=1.64, atmrad=2.64, vdwrad=0.0,         tboil=3347.0, tmelt=1294.0, density=7.0,         eleconfig='[Xe] 4f4 6s2',         oxistates='3*',         ionenergy=(5.525, 10.72),         isotopes={             142: Isotope(141.907729, 0.27152, 142),             143: Isotope(142.90982, 0.12174, 143),             144: Isotope(143.910093, 0.23798, 144),             145: Isotope(144.9125793, 0.08293, 145),             146: Isotope(145.9131226, 0.17189, 146),             148: Isotope(147.9168993, 0.05756, 148),             150: Isotope(149.9209022, 0.05638, 150),         },     ),     Element(         61, 'Pm', 'Promethium',         group=3, period=6, block='f', series=9,         mass=144.9128, eleneg=1.13, eleaffin=0.5,         covrad=1.63, atmrad=2.62, vdwrad=0.0,         tboil=3273.0, tmelt=1315.0, density=7.22,         eleconfig='[Xe] 4f5 6s2',         oxistates='3*',         ionenergy=(5.582, 10.9),         isotopes={145: Isotope(144.9127559, 1.0, 145)},     ),     Element(         62, 'Sm', 'Samarium',         group=3, period=6, block='f', series=9,         mass=150.36, eleneg=1.17, eleaffin=0.5,         covrad=1.62, atmrad=2.59, vdwrad=0.0,         tboil=2067.0, tmelt=1347.0, density=7.54,         eleconfig='[Xe] 4f6 6s2',         oxistates='3*, 2',         ionenergy=(5.6437, 11.07),         isotopes={             144: Isotope(143.9120065, 0.0307, 144),             147: Isotope(146.9149044, 0.1499, 147),             148: Isotope(147.9148292, 0.1124, 148),             149: Isotope(148.9171921, 0.1382, 149),             150: Isotope(149.9172829, 0.0738, 150),             152: Isotope(151.9197397, 0.2675, 152),             154: Isotope(153.9222169, 0.2275, 154),         },     ),     Element(         63, 'Eu', 'Europium',         group=3, period=6, block='f', series=9,         mass=151.964, eleneg=1.2, eleaffin=0.5,         covrad=1.85, atmrad=2.56, vdwrad=0.0,         tboil=1800.0, tmelt=1095.0, density=5.25,         eleconfig='[Xe] 4f7 6s2',         oxistates='3*, 2',         ionenergy=(5.6704, 11.25),         isotopes={             151: Isotope(150.9198578, 0.4781, 151),             153: Isotope(152.921238, 0.5219, 153),         },     ),     Element(         64, 'Gd', 'Gadolinium',         group=3, period=6, block='f', series=9,         mass=157.25, eleneg=1.2, eleaffin=0.5,         covrad=1.61, atmrad=2.54, vdwrad=0.0,         tboil=3545.0, tmelt=1585.0, density=7.89,         eleconfig='[Xe] 4f7 5d 6s2',         oxistates='3*',         ionenergy=(6.1498, 12.1),         isotopes={             152: Isotope(151.9197995, 0.002, 152),             154: Isotope(153.9208741, 0.0218, 154),             155: Isotope(154.9226305, 0.148, 155),             156: Isotope(155.9221312, 0.2047, 156),             157: Isotope(156.9239686, 0.1565, 157),             158: Isotope(157.9241123, 0.2484, 158),             160: Isotope(159.9270624, 0.2186, 160),         },     ),     Element(         65, 'Tb', 'Terbium',         group=3, period=6, block='f', series=9,         mass=158.92535, eleneg=1.2, eleaffin=0.5,         covrad=1.59, atmrad=2.51, vdwrad=0.0,         tboil=3500.0, tmelt=1629.0, density=8.25,         eleconfig='[Xe] 4f9 6s2',         oxistates='4, 3*',         ionenergy=(5.8638, 11.52),         isotopes={159: Isotope(158.9253547, 1.0, 159)},     ),     Element(         66, 'Dy', 'Dysprosium',         group=3, period=6, block='f', series=9,         mass=162.5, eleneg=1.22, eleaffin=0.5,         covrad=1.59, atmrad=2.49, vdwrad=0.0,         tboil=2840.0, tmelt=1685.0, density=8.56,         eleconfig='[Xe] 4f10 6s2',         oxistates='3*',         ionenergy=(5.9389, 11.67),         isotopes={             156: Isotope(155.9242847, 0.00056, 156),             158: Isotope(157.9244159, 0.00095, 158),             160: Isotope(159.9252046, 0.02329, 160),             161: Isotope(160.9269405, 0.18889, 161),             162: Isotope(161.9268056, 0.25475, 162),             163: Isotope(162.9287383, 0.24896, 163),             164: Isotope(163.9291819, 0.2826, 164),         },     ),     Element(         67, 'Ho', 'Holmium',         group=3, period=6, block='f', series=9,         mass=164.93033, eleneg=1.23, eleaffin=0.5,         covrad=1.58, atmrad=2.47, vdwrad=0.0,         tboil=2968.0, tmelt=1747.0, density=8.78,         eleconfig='[Xe] 4f11 6s2',         oxistates='3*',         ionenergy=(6.0215, 11.8),         isotopes={165: Isotope(164.9303288, 1.0, 165)},     ),     Element(         68, 'Er', 'Erbium',         group=3, period=6, block='f', series=9,         mass=167.259, eleneg=1.24, eleaffin=0.5,         covrad=1.57, atmrad=2.45, vdwrad=0.0,         tboil=3140.0, tmelt=1802.0, density=9.05,         eleconfig='[Xe] 4f12 6s2',         oxistates='3*',         ionenergy=(6.1077, 11.93),         isotopes={             162: Isotope(161.9287884, 0.00139, 162),             164: Isotope(163.9292088, 0.01601, 164),             166: Isotope(165.9302995, 0.33503, 166),             167: Isotope(166.9320546, 0.22869, 167),             168: Isotope(167.9323767, 0.26978, 168),             170: Isotope(169.9354702, 0.1491, 170),         },     ),     Element(         69, 'Tm', 'Thulium',         group=3, period=6, block='f', series=9,         mass=168.93422, eleneg=1.25, eleaffin=0.5,         covrad=1.56, atmrad=2.42, vdwrad=0.0,         tboil=2223.0, tmelt=1818.0, density=9.32,         eleconfig='[Xe] 4f13 6s2',         oxistates='3*, 2',         ionenergy=(6.1843, 12.05, 23.71),         isotopes={169: Isotope(168.9342179, 1.0, 169)},     ),     Element(         70, 'Yb', 'Ytterbium',         group=3, period=6, block='f', series=9,         mass=173.054, eleneg=1.1, eleaffin=0.5,         covrad=1.74, atmrad=2.4, vdwrad=0.0,         tboil=1469.0, tmelt=1092.0, density=9.32,         eleconfig='[Xe] 4f14 6s2',         oxistates='3*, 2',         ionenergy=(6.2542, 12.17, 25.2),         isotopes={             168: Isotope(167.9338896, 0.00123, 168),             170: Isotope(169.9347664, 0.02982, 170),             171: Isotope(170.9363302, 0.1409, 171),             172: Isotope(171.9363859, 0.2168, 172),             173: Isotope(172.9382151, 0.16103, 173),             174: Isotope(173.9388664, 0.32026, 174),             176: Isotope(175.9425764, 0.12996, 176),         },     ),     Element(         71, 'Lu', 'Lutetium',         group=3, period=6, block='d', series=9,         mass=174.9668, eleneg=1.27, eleaffin=0.5,         covrad=1.56, atmrad=2.25, vdwrad=0.0,         tboil=3668.0, tmelt=1936.0, density=9.84,         eleconfig='[Xe] 4f14 5d 6s2',         oxistates='3*',         ionenergy=(5.4259, 13.9),         isotopes={             175: Isotope(174.9407752, 0.97401, 175),             176: Isotope(175.9426897, 0.02599, 176),         },     ),     Element(         72, 'Hf', 'Hafnium',         group=4, period=6, block='d', series=8,         mass=178.49, eleneg=1.3, eleaffin=0.0,         covrad=1.44, atmrad=2.16, vdwrad=0.0,         tboil=4875.0, tmelt=2504.0, density=13.31,         eleconfig='[Xe] 4f14 5d2 6s2',         oxistates='4*',         ionenergy=(6.8251, 14.9, 23.3, 33.3),         isotopes={             174: Isotope(173.9400461, 0.0016, 174),             176: Isotope(175.9414076, 0.0526, 176),             177: Isotope(176.9432277, 0.186, 177),             178: Isotope(177.9437058, 0.2728, 178),             179: Isotope(178.9458232, 0.1362, 179),             180: Isotope(179.946557, 0.3508, 180),         },     ),     Element(         73, 'Ta', 'Tantalum',         group=5, period=6, block='d', series=8,         mass=180.94788, eleneg=1.5, eleaffin=0.322,         covrad=1.34, atmrad=2.09, vdwrad=0.0,         tboil=5730.0, tmelt=3293.0, density=16.68,         eleconfig='[Xe] 4f14 5d3 6s2',         oxistates='5*',         ionenergy=(7.5496,),         isotopes={             180: Isotope(179.9474648, 0.0001201, 180),             181: Isotope(180.9479958, 0.9998799, 181),         },     ),     Element(         74, 'W', 'Tungsten',         group=6, period=6, block='d', series=8,         mass=183.84, eleneg=2.36, eleaffin=0.815,         covrad=1.3, atmrad=2.02, vdwrad=0.0,         tboil=5825.0, tmelt=3695.0, density=19.26,         eleconfig='[Xe] 4f14 5d4 6s2',         oxistates='6*, 5, 4, 3, 2, 0',         ionenergy=(7.864,),         isotopes={             180: Isotope(179.9467108, 0.0012, 180),             182: Isotope(181.94820394, 0.265, 182),             183: Isotope(182.95022275, 0.1431, 183),             184: Isotope(183.95093092, 0.3064, 184),             186: Isotope(185.9543628, 0.2843, 186),         },     ),     Element(         75, 'Re', 'Rhenium',         group=7, period=6, block='d', series=8,         mass=186.207, eleneg=1.9, eleaffin=0.15,         covrad=1.28, atmrad=1.97, vdwrad=0.0,         tboil=5870.0, tmelt=3455.0, density=21.03,         eleconfig='[Xe] 4f14 5d5 6s2',         oxistates='7, 6, 4, 2, -1',         ionenergy=(7.8335,),         isotopes={             185: Isotope(184.9529545, 0.374, 185),             187: Isotope(186.9557501, 0.626, 187),         },     ),     Element(         76, 'Os', 'Osmium',         group=8, period=6, block='d', series=8,         mass=190.23, eleneg=2.2, eleaffin=1.0778,         covrad=1.26, atmrad=1.92, vdwrad=0.0,         tboil=5300.0, tmelt=3300.0, density=22.61,         eleconfig='[Xe] 4f14 5d6 6s2',         oxistates='8, 6, 4*, 3, 2, 0, -2',         ionenergy=(8.4382,),         isotopes={             184: Isotope(183.9524885, 0.0002, 184),             186: Isotope(185.953835, 0.0159, 186),             187: Isotope(186.9557474, 0.0196, 187),             188: Isotope(187.9558352, 0.1324, 188),             189: Isotope(188.9581442, 0.1615, 189),             190: Isotope(189.9584437, 0.2626, 190),             192: Isotope(191.961477, 0.4078, 192),         },     ),     Element(         77, 'Ir', 'Iridium',         group=9, period=6, block='d', series=8,         mass=192.217, eleneg=2.2, eleaffin=1.56436,         covrad=1.27, atmrad=1.87, vdwrad=0.0,         tboil=4700.0, tmelt=2720.0, density=22.65,         eleconfig='[Xe] 4f14 5d7 6s2',         oxistates='6, 4*, 3, 2, 1*, 0, -1',         ionenergy=(8.967,),         isotopes={             191: Isotope(190.9605893, 0.373, 191),             193: Isotope(192.9629216, 0.627, 193),         },     ),     Element(         78, 'Pt', 'Platinum',         group=10, period=6, block='d', series=8,         mass=195.084, eleneg=2.28, eleaffin=2.1251,         covrad=1.3, atmrad=1.83, vdwrad=1.75,         tboil=4100.0, tmelt=2042.1, density=21.45,         eleconfig='[Xe] 4f14 5d9 6s',         oxistates='4*, 2*, 0',         ionenergy=(8.9588, 18.563),         isotopes={             190: Isotope(189.9599297, 0.00012, 190),             192: Isotope(191.9610387, 0.00782, 192),             194: Isotope(193.9626809, 0.3286, 194),             195: Isotope(194.9647917, 0.3378, 195),             196: Isotope(195.96495209, 0.2521, 196),             198: Isotope(197.9678949, 0.07356, 198),         },     ),     Element(         79, 'Au', 'Gold',         group=11, period=6, block='d', series=8,         mass=196.966569, eleneg=2.54, eleaffin=2.30861,         covrad=1.34, atmrad=1.79, vdwrad=1.66,         tboil=3130.0, tmelt=1337.58, density=19.32,         eleconfig='[Xe] 4f14 5d10 6s',         oxistates='3*, 1',         ionenergy=(9.2255, 20.5),         isotopes={197: Isotope(196.96656879, 1.0, 197)},     ),     Element(         80, 'Hg', 'Mercury',         group=12, period=6, block='d', series=8,         mass=200.592, eleneg=2.0, eleaffin=0.0,         covrad=1.49, atmrad=1.76, vdwrad=0.0,         tboil=629.88, tmelt=234.31, density=13.55,         eleconfig='[Xe] 4f14 5d10 6s2',         oxistates='2*, 1',         ionenergy=(10.4375, 18.756, 34.2),         isotopes={             196: Isotope(195.9658326, 0.0015, 196),             198: Isotope(197.9667686, 0.0997, 198),             199: Isotope(198.96828064, 0.1687, 199),             200: Isotope(199.96832659, 0.231, 200),             201: Isotope(200.97030284, 0.1318, 201),             202: Isotope(201.9706434, 0.2986, 202),             204: Isotope(203.97349398, 0.0687, 204),         },     ),     Element(         81, 'Tl', 'Thallium',         group=13, period=6, block='p', series=7,         mass=204.3834, eleneg=2.04, eleaffin=0.377,         covrad=1.48, atmrad=2.08, vdwrad=1.96,         tboil=1746.0, tmelt=577.0, density=11.85,         eleconfig='[Xe] 4f14 5d10 6s2 6p',         oxistates='3, 1*',         ionenergy=(6.1082, 20.428, 29.83),         isotopes={             203: Isotope(202.9723446, 0.2952, 203),             205: Isotope(204.9744278, 0.7048, 205),         },     ),     Element(         82, 'Pb', 'Lead',         group=14, period=6, block='p', series=7,         mass=207.2, eleneg=2.33, eleaffin=0.364,         covrad=1.47, atmrad=1.81, vdwrad=2.02,         tboil=2023.0, tmelt=600.65, density=11.34,         eleconfig='[Xe] 4f14 5d10 6s2 6p2',         oxistates='4, 2*',         ionenergy=(7.4167, 15.032, 31.937, 42.32, 68.8),         isotopes={             204: Isotope(203.973044, 0.014, 204),             206: Isotope(205.9744657, 0.241, 206),             207: Isotope(206.9758973, 0.221, 207),             208: Isotope(207.9766525, 0.524, 208),         },     ),     Element(         83, 'Bi', 'Bismuth',         group=15, period=6, block='p', series=7,         mass=208.9804, eleneg=2.02, eleaffin=0.942363,         covrad=1.46, atmrad=1.63, vdwrad=0.0,         tboil=1837.0, tmelt=544.59, density=9.8,         eleconfig='[Xe] 4f14 5d10 6s2 6p3',         oxistates='5, 3*',         ionenergy=(             7.2855, 16.69, 25.56, 45.3, 56.0,             88.3,         ),         isotopes={209: Isotope(208.9803991, 1.0, 209)},     ),     Element(         84, 'Po', 'Polonium',         group=16, period=6, block='p', series=5,         mass=208.9824, eleneg=2.0, eleaffin=1.9,         covrad=1.46, atmrad=1.53, vdwrad=0.0,         tboil=0.0, tmelt=527.0, density=9.2,         eleconfig='[Xe] 4f14 5d10 6s2 6p4',         oxistates='6, 4*, 2',         ionenergy=(8.414,),         isotopes={209: Isotope(208.9824308, 1.0, 209)},     ),     Element(         85, 'At', 'Astatine',         group=17, period=6, block='p', series=6,         mass=209.9871, eleneg=2.2, eleaffin=2.8,         covrad=1.45, atmrad=1.43, vdwrad=0.0,         tboil=610.0, tmelt=575.0, density=0.0,         eleconfig='[Xe] 4f14 5d10 6s2 6p5',         oxistates='7, 5, 3, 1, -1*',         ionenergy=(),         isotopes={210: Isotope(209.9871479, 1.0, 210)},     ),     Element(         86, 'Rn', 'Radon',         group=18, period=6, block='p', series=2,         mass=222.0176, eleneg=0.0, eleaffin=0.0,         covrad=0.0, atmrad=1.34, vdwrad=0.0,         tboil=211.4, tmelt=202.0, density=9.23,         eleconfig='[Xe] 4f14 5d10 6s2 6p6',         oxistates='2*',         ionenergy=(10.7485,),         isotopes={222: Isotope(222.0175782, 1.0, 222)},     ),     Element(         87, 'Fr', 'Francium',         group=1, period=7, block='s', series=3,         mass=223.0197, eleneg=0.7, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=950.0, tmelt=300.0, density=0.0,         eleconfig='[Rn] 7s',         oxistates='1*',         ionenergy=(4.0727,),         isotopes={223: Isotope(223.019736, 1.0, 223)},     ),     Element(         88, 'Ra', 'Radium',         group=2, period=7, block='s', series=4,         mass=226.0254, eleneg=0.9, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=1413.0, tmelt=973.0, density=5.5,         eleconfig='[Rn] 7s2',         oxistates='2*',         ionenergy=(5.2784, 10.147),         isotopes={226: Isotope(226.0254103, 1.0, 226)},     ),     Element(         89, 'Ac', 'Actinium',         group=3, period=7, block='f', series=10,         mass=227.0278, eleneg=1.1, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=3470.0, tmelt=1324.0, density=10.07,         eleconfig='[Rn] 6d 7s2',         oxistates='3*',         ionenergy=(5.17, 12.1),         isotopes={227: Isotope(227.0277523, 1.0, 227)},     ),     Element(         90, 'Th', 'Thorium',         group=3, period=7, block='f', series=10,         mass=232.0377, eleneg=1.3, eleaffin=0.0,         covrad=1.65, atmrad=0.0, vdwrad=0.0,         tboil=5060.0, tmelt=2028.0, density=11.72,         eleconfig='[Rn] 6d2 7s2',         oxistates='4*',         ionenergy=(6.3067, 11.5, 20.0, 28.8),         isotopes={232: Isotope(232.0380558, 1.0, 232)},     ),     Element(         91, 'Pa', 'Protactinium',         group=3, period=7, block='f', series=10,         mass=231.03588, eleneg=1.5, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=4300.0, tmelt=1845.0, density=15.37,         eleconfig='[Rn] 5f2 6d 7s2',         oxistates='5*, 4',         ionenergy=(5.89,),         isotopes={231: Isotope(231.0358842, 1.0, 231)},     ),     Element(         92, 'U', 'Uranium',         group=3, period=7, block='f', series=10,         mass=238.02891, eleneg=1.38, eleaffin=0.0,         covrad=1.42, atmrad=0.0, vdwrad=1.86,         tboil=4407.0, tmelt=1408.0, density=18.97,         eleconfig='[Rn] 5f3 6d 7s2',         oxistates='6*, 5, 4, 3',         ionenergy=(6.1941,),         isotopes={             234: Isotope(234.0409523, 5.4e-05, 234),             235: Isotope(235.0439301, 0.007204, 235),             238: Isotope(238.0507884, 0.992742, 238),         },     ),     Element(         93, 'Np', 'Neptunium',         group=3, period=7, block='f', series=10,         mass=237.0482, eleneg=1.36, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=4175.0, tmelt=912.0, density=20.48,         eleconfig='[Rn] 5f4 6d 7s2',         oxistates='6, 5*, 4, 3',         ionenergy=(6.2657,),         isotopes={237: Isotope(237.0481736, 1.0, 237)},     ),     Element(         94, 'Pu', 'Plutonium',         group=3, period=7, block='f', series=10,         mass=244.0642, eleneg=1.28, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=3505.0, tmelt=913.0, density=19.74,         eleconfig='[Rn] 5f6 7s2',         oxistates='6, 5, 4*, 3',         ionenergy=(6.026,),         isotopes={244: Isotope(244.0642053, 1.0, 244)},     ),     Element(         95, 'Am', 'Americium',         group=3, period=7, block='f', series=10,         mass=243.0614, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=2880.0, tmelt=1449.0, density=13.67,         eleconfig='[Rn] 5f7 7s2',         oxistates='6, 5, 4, 3*',         ionenergy=(5.9738,),         isotopes={243: Isotope(243.0613813, 1.0, 243)},     ),     Element(         96, 'Cm', 'Curium',         group=3, period=7, block='f', series=10,         mass=247.0704, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=1620.0, density=13.51,         eleconfig='[Rn] 5f7 6d 7s2',         oxistates='4, 3*',         ionenergy=(5.9914,),         isotopes={247: Isotope(247.0703541, 1.0, 247)},     ),     Element(         97, 'Bk', 'Berkelium',         group=3, period=7, block='f', series=10,         mass=247.0703, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=1258.0, density=13.25,         eleconfig='[Rn] 5f9 7s2',         oxistates='4, 3*',         ionenergy=(6.1979,),         isotopes={247: Isotope(247.0703073, 1.0, 247)},     ),     Element(         98, 'Cf', 'Californium',         group=3, period=7, block='f', series=10,         mass=251.0796, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=1172.0, density=15.1,         eleconfig='[Rn] 5f10 7s2',         oxistates='4, 3*',         ionenergy=(6.2817,),         isotopes={251: Isotope(251.0795886, 1.0, 251)},     ),     Element(         99, 'Es', 'Einsteinium',         group=3, period=7, block='f', series=10,         mass=252.083, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=1130.0, density=0.0,         eleconfig='[Rn] 5f11 7s2',         oxistates='3*',         ionenergy=(6.42,),         isotopes={252: Isotope(252.08298, 1.0, 252)},     ),     Element(         100, 'Fm', 'Fermium',         group=3, period=7, block='f', series=10,         mass=257.0951, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=1800.0, density=0.0,         eleconfig='[Rn] 5f12 7s2',         oxistates='3*',         ionenergy=(6.5,),         isotopes={257: Isotope(257.0951061, 1.0, 257)},     ),     Element(         101, 'Md', 'Mendelevium',         group=3, period=7, block='f', series=10,         mass=258.0984, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=1100.0, density=0.0,         eleconfig='[Rn] 5f13 7s2',         oxistates='3*',         ionenergy=(6.58,),         isotopes={258: Isotope(258.0984315, 1.0, 258)},     ),     Element(         102, 'No', 'Nobelium',         group=3, period=7, block='f', series=10,         mass=259.101, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=1100.0, density=0.0,         eleconfig='[Rn] 5f14 7s2',         oxistates='3, 2*',         ionenergy=(6.65,),         isotopes={259: Isotope(259.10103, 1.0, 259)},     ),     Element(         103, 'Lr', 'Lawrencium',         group=3, period=7, block='d', series=10,         mass=262.1096, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=1900.0, density=0.0,         eleconfig='[Rn] 5f14 6d 7s2',         oxistates='3*',         ionenergy=(4.9,),         isotopes={262: Isotope(262.10961, 1.0, 262)},     ),     Element(         104, 'Rf', 'Rutherfordium',         group=4, period=7, block='d', series=8,         mass=267.1218, eleneg=0.0, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=0.0, density=0.0,         eleconfig='[Rn] 5f14 6d2 7s2',         oxistates='*',         ionenergy=(6.0,),         isotopes={267: Isotope(267.12179, 1.0, 267)},     ),     Element(         105, 'Db', 'Dubnium',         group=5, period=7, block='d', series=8,         mass=268.1257, eleneg=0.0, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=0.0, density=0.0,         eleconfig='[Rn] 5f14 6d3 7s2',         oxistates='*',         ionenergy=(),         isotopes={268: Isotope(268.12567, 1.0, 268)},     ),     Element(         106, 'Sg', 'Seaborgium',         group=6, period=7, block='d', series=8,         mass=271.1339, eleneg=0.0, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=0.0, density=0.0,         eleconfig='[Rn] 5f14 6d4 7s2',         oxistates='*',         ionenergy=(),         isotopes={271: Isotope(271.13393, 1.0, 271)},     ),     Element(         107, 'Bh', 'Bohrium',         group=7, period=7, block='d', series=8,         mass=272.1383, eleneg=0.0, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=0.0, density=0.0,         eleconfig='[Rn] 5f14 6d5 7s2',         oxistates='*',         ionenergy=(),         isotopes={272: Isotope(272.13826, 1.0, 272)},     ),     Element(         108, 'Hs', 'Hassium',         group=8, period=7, block='d', series=8,         mass=270.1343, eleneg=0.0, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=0.0, density=0.0,         eleconfig='[Rn] 5f14 6d6 7s2',         oxistates='*',         ionenergy=(),         isotopes={270: Isotope(270.13429, 1.0, 270)},     ),     Element(         109, 'Mt', 'Meitnerium',         group=9, period=7, block='d', series=8,         mass=276.1516, eleneg=0.0, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=0.0, density=0.0,         eleconfig='[Rn] 5f14 6d7 7s2',         oxistates='*',         ionenergy=(),         isotopes={276: Isotope(276.15159, 1.0, 276)},     ), )

Collection of chemical elements with lookup by number, symbol, and name.

An ordered collection of Element instances with lookup by atomic number (int), chemical symbol (str), or element name (str).

molmass.GROUPS

molmass.NEUTRON = Particle(name='Neutron', mass=1.00866491595, charge=0.0)

Neutron particle.

molmass.NUCLEOTIDES

molmass.POSITRON = Particle(name='Positron', mass=0.000548579909065, charge=1.602176634e-19)

Positron or antielectron particle.

molmass.PREPROCESSORS

molmass.PROTON = Particle(name='Proton', mass=1.007276466621, charge=1.602176634e-19)

Proton particle.

molmass.elements

class molmass.elements.Element(number, symbol, name, group, period, block, series, mass, eleneg, eleaffin, covrad, atmrad, vdwrad, tboil, tmelt, density, eleconfig, oxistates, ionenergy, isotopes)

Bases: object

Chemical element.

Parameters:

• number (int)

• symbol (str)

• name (str)

• group (int)

• period (int)

• block (str)

• series (int)

• mass (float)

• eleneg (float)

• eleaffin (float)

• covrad (float)

• atmrad (float)

• vdwrad (float)

• tboil (float)

• tmelt (float)

• density (float)

• eleconfig (str)

• oxistates (str)

• ionenergy (tuple[float, ...])

• isotopes (dict[int, Isotope])

number: int

Atomic number of protons.

symbol: str

Chemical symbol.

name: str

English name.

group: int

Group in periodic table.

period: int

Period in periodic table.

block: str

Block in periodic table.

series: int

Index to chemical series.

mass: float

Relative atomic mass.

The ratio of the average mass of atoms of the element to 1/12 of the mass of an atom of 12C.

eleneg: float

Electronegativity on Pauling scale.

eleaffin: float

Electron affinity in eV.

covrad: float

Covalent radius in angstrom.

atmrad: float

Atomic radius in angstrom.

vdwrad: float

Van der Waals radius in angstrom.

tboil: float

Boiling temperature in K.

tmelt: float

Melting temperature in K.

density: float

Density at 295K in g/cm3 respectively g/L.

eleconfig: str

Ground state electron configuration.

oxistates: str

Oxidation states.

ionenergy: tuple[float, ...]

Ionization energies in eV.

isotopes: dict[int, Isotope]

Isotopic composition.

Mapping of isotope mass number to relative atomic mass and abundance.

property protons: int

Number of protons.

property electrons: int

Number of electrons.

property neutrons: int

Number of neutrons in most abundant natural stable isotope.

property nominalmass: int

Mass number of most abundant natural stable isotope.

property exactmass: float

Relative atomic mass calculated from isotopic composition.

property eleconfig_dict: dict[tuple[int, str], int]

electrons.

Type:

Ground state electron configuration (shell, subshell)

property eleshells: tuple[int, ...]

Number of electrons in shell.

property description: str

Text description of element.

validate()

Check consistency of data. Raise ValueError on failure.

Return type:

None

__repr__()

Return repr(self).

Return type:

str

__str__()

Return str(self).

Return type:

str

__eq__(other)

Return self==value.

__init__(number, symbol, name, group, period, block, series, mass, eleneg, eleaffin, covrad, atmrad, vdwrad, tboil, tmelt, density, eleconfig, oxistates, ionenergy, isotopes)

Parameters:

• number (int)

• symbol (str)

• name (str)

• group (int)

• period (int)

• block (str)

• series (int)

• mass (float)

• eleneg (float)

• eleaffin (float)

• covrad (float)

• atmrad (float)

• vdwrad (float)

• tboil (float)

• tmelt (float)

• density (float)

• eleconfig (str)

• oxistates (str)

• ionenergy (tuple[float, ...])

• isotopes (dict[int, Isotope])

Return type:

None

__weakref__

list of weak references to the object

class molmass.elements.Isotope(mass, abundance, massnumber, charge=0)

Bases: object

Isotope properties.

Parameters:

• mass (float)

• abundance (float)

• massnumber (int)

• charge (int)

mass: float

Monoisotopic mass.

abundance: float

Natural fraction on Earth.

massnumber: int

Number of protons and neutrons.

charge: int = 0

Net charge in units of elementary charge.

property mz: float

Mass-to-charge ratio.

__eq__(other)

Return self==value.

__init__(mass, abundance, massnumber, charge=0)

Parameters:

• mass (float)

• abundance (float)

• massnumber (int)

• charge (int)

Return type:

None

__repr__()

Return repr(self).

__weakref__

list of weak references to the object

class molmass.elements.Particle(name, mass, charge)

Bases: object

Particle, e.g., electron, proton, or neutron.

Parameters:

• name (str)

• mass (float)

• charge (float)

name: str

English name.

__eq__(other)

Return self==value.

__init__(name, mass, charge)

Parameters:

• name (str)

• mass (float)

• charge (float)

Return type:

None

__repr__()

Return repr(self).

__weakref__

list of weak references to the object

mass: float

Relative mass.

The ratio of the average mass of atoms of the particle to 1/12 of the mass of an atom of 12C.

charge: float

Electric charge in coulomb.

__str__()

Return str(self).

Return type:

str

molmass.elements.ELECTRON: Particle = Particle(name='Electron', mass=0.000548579909065, charge=-1.602176634e-19)

Electron particle.

molmass.elements.ELEMENTARY_CHARGE: float = 1.602176634e-19

Elementary charge in coulombs.

molmass.elements.ELEMENTS: Elements = Elements(     Element(         1, 'H', 'Hydrogen',         group=1, period=1, block='s', series=1,         mass=1.007941, eleneg=2.2, eleaffin=0.75420375,         covrad=0.32, atmrad=0.79, vdwrad=1.2,         tboil=20.28, tmelt=13.81, density=0.084,         eleconfig='1s',         oxistates='1*, -1',         ionenergy=(13.5984,),         isotopes={             1: Isotope(1.00782503223, 0.999885, 1),             2: Isotope(2.01410177812, 0.000115, 2),         },     ),     Element(         2, 'He', 'Helium',         group=18, period=1, block='s', series=2,         mass=4.002602, eleneg=0.0, eleaffin=0.0,         covrad=0.93, atmrad=0.49, vdwrad=1.4,         tboil=4.216, tmelt=0.95, density=0.1785,         eleconfig='1s2',         oxistates='*',         ionenergy=(24.5874, 54.416),         isotopes={             3: Isotope(3.0160293201, 1.34e-06, 3),             4: Isotope(4.00260325413, 0.99999866, 4),         },     ),     Element(         3, 'Li', 'Lithium',         group=1, period=2, block='s', series=3,         mass=6.94, eleneg=0.98, eleaffin=0.618049,         covrad=1.23, atmrad=2.05, vdwrad=1.82,         tboil=1615.0, tmelt=453.7, density=0.53,         eleconfig='[He] 2s',         oxistates='1*',         ionenergy=(5.3917, 75.638, 122.451),         isotopes={             6: Isotope(6.0151228874, 0.0759, 6),             7: Isotope(7.0160034366, 0.9241, 7),         },     ),     Element(         4, 'Be', 'Beryllium',         group=2, period=2, block='s', series=4,         mass=9.0121831, eleneg=1.57, eleaffin=0.0,         covrad=0.9, atmrad=1.4, vdwrad=0.0,         tboil=3243.0, tmelt=1560.0, density=1.85,         eleconfig='[He] 2s2',         oxistates='2*',         ionenergy=(9.3227, 18.211, 153.893, 217.713),         isotopes={9: Isotope(9.012183065, 1.0, 9)},     ),     Element(         5, 'B', 'Boron',         group=13, period=2, block='p', series=5,         mass=10.811, eleneg=2.04, eleaffin=0.279723,         covrad=0.82, atmrad=1.17, vdwrad=0.0,         tboil=4275.0, tmelt=2365.0, density=2.46,         eleconfig='[He] 2s2 2p',         oxistates='3*',         ionenergy=(8.298, 25.154, 37.93, 59.368, 340.217),         isotopes={             10: Isotope(10.01293695, 0.199, 10),             11: Isotope(11.00930536, 0.801, 11),         },     ),     Element(         6, 'C', 'Carbon',         group=14, period=2, block='p', series=1,         mass=12.01074, eleneg=2.55, eleaffin=1.262118,         covrad=0.77, atmrad=0.91, vdwrad=1.7,         tboil=5100.0, tmelt=3825.0, density=3.51,         eleconfig='[He] 2s2 2p2',         oxistates='4*, 2, -4*',         ionenergy=(             11.2603, 24.383, 47.877, 64.492, 392.077,             489.981,         ),         isotopes={             12: Isotope(12.0, 0.9893, 12),             13: Isotope(13.00335483507, 0.0107, 13),         },     ),     Element(         7, 'N', 'Nitrogen',         group=15, period=2, block='p', series=1,         mass=14.006703, eleneg=3.04, eleaffin=-0.07,         covrad=0.75, atmrad=0.75, vdwrad=1.55,         tboil=77.344, tmelt=63.15, density=1.17,         eleconfig='[He] 2s2 2p3',         oxistates='5, 4, 3, 2, -3*',         ionenergy=(             14.5341, 39.601, 47.488, 77.472, 97.888,             522.057, 667.029,         ),         isotopes={             14: Isotope(14.00307400443, 0.99636, 14),             15: Isotope(15.00010889888, 0.00364, 15),         },     ),     Element(         8, 'O', 'Oxygen',         group=16, period=2, block='p', series=1,         mass=15.999405, eleneg=3.44, eleaffin=1.461112,         covrad=0.73, atmrad=0.65, vdwrad=1.52,         tboil=90.188, tmelt=54.8, density=1.33,         eleconfig='[He] 2s2 2p4',         oxistates='-2*, -1',         ionenergy=(             13.6181, 35.116, 54.934, 77.412, 113.896,             138.116, 739.315, 871.387,         ),         isotopes={             16: Isotope(15.99491461957, 0.99757, 16),             17: Isotope(16.9991317565, 0.00038, 17),             18: Isotope(17.99915961286, 0.00205, 18),         },     ),     Element(         9, 'F', 'Fluorine',         group=17, period=2, block='p', series=6,         mass=18.998403163, eleneg=3.98, eleaffin=3.4011887,         covrad=0.72, atmrad=0.57, vdwrad=1.47,         tboil=85.0, tmelt=53.55, density=1.58,         eleconfig='[He] 2s2 2p5',         oxistates='-1*',         ionenergy=(             17.4228, 34.97, 62.707, 87.138, 114.24,             157.161, 185.182, 953.886, 1103.089,         ),         isotopes={19: Isotope(18.99840316273, 1.0, 19)},     ),     Element(         10, 'Ne', 'Neon',         group=18, period=2, block='p', series=2,         mass=20.1797, eleneg=0.0, eleaffin=0.0,         covrad=0.71, atmrad=0.51, vdwrad=1.54,         tboil=27.1, tmelt=24.55, density=0.8999,         eleconfig='[He] 2s2 2p6',         oxistates='*',         ionenergy=(             21.5645, 40.962, 63.45, 97.11, 126.21,             157.93, 207.27, 239.09, 1195.797, 1362.164,         ),         isotopes={             20: Isotope(19.9924401762, 0.9048, 20),             21: Isotope(20.993846685, 0.0027, 21),             22: Isotope(21.991385114, 0.0925, 22),         },     ),     Element(         11, 'Na', 'Sodium',         group=1, period=3, block='s', series=3,         mass=22.98976928, eleneg=0.93, eleaffin=0.547926,         covrad=1.54, atmrad=2.23, vdwrad=2.27,         tboil=1156.0, tmelt=371.0, density=0.97,         eleconfig='[Ne] 3s',         oxistates='1*',         ionenergy=(             5.1391, 47.286, 71.64, 98.91, 138.39,             172.15, 208.47, 264.18, 299.87, 1465.091,             1648.659,         ),         isotopes={23: Isotope(22.989769282, 1.0, 23)},     ),     Element(         12, 'Mg', 'Magnesium',         group=2, period=3, block='s', series=4,         mass=24.3051, eleneg=1.31, eleaffin=0.0,         covrad=1.36, atmrad=1.72, vdwrad=1.73,         tboil=1380.0, tmelt=922.0, density=1.74,         eleconfig='[Ne] 3s2',         oxistates='2*',         ionenergy=(             7.6462, 15.035, 80.143, 109.24, 141.26,             186.5, 224.94, 265.9, 327.95, 367.53,             1761.802, 1962.613,         ),         isotopes={             24: Isotope(23.985041697, 0.7899, 24),             25: Isotope(24.985836976, 0.1, 25),             26: Isotope(25.982592968, 0.1101, 26),         },     ),     Element(         13, 'Al', 'Aluminium',         group=13, period=3, block='p', series=7,         mass=26.9815385, eleneg=1.61, eleaffin=0.43283,         covrad=1.18, atmrad=1.82, vdwrad=0.0,         tboil=2740.0, tmelt=933.5, density=2.7,         eleconfig='[Ne] 3s2 3p',         oxistates='3*',         ionenergy=(             5.9858, 18.828, 28.447, 119.99, 153.71,             190.47, 241.43, 284.59, 330.21, 398.57,             442.07, 2085.983, 2304.08,         ),         isotopes={27: Isotope(26.98153853, 1.0, 27)},     ),     Element(         14, 'Si', 'Silicon',         group=14, period=3, block='p', series=5,         mass=28.0855, eleneg=1.9, eleaffin=1.389521,         covrad=1.11, atmrad=1.46, vdwrad=2.1,         tboil=2630.0, tmelt=1683.0, density=2.33,         eleconfig='[Ne] 3s2 3p2',         oxistates='4*, -4',         ionenergy=(             8.1517, 16.345, 33.492, 45.141, 166.77,             205.05, 246.52, 303.17, 351.1, 401.43,             476.06, 523.5, 2437.676, 2673.108,         ),         isotopes={             28: Isotope(27.97692653465, 0.92223, 28),             29: Isotope(28.9764946649, 0.04685, 29),             30: Isotope(29.973770136, 0.03092, 30),         },     ),     Element(         15, 'P', 'Phosphorus',         group=15, period=3, block='p', series=1,         mass=30.973761998, eleneg=2.19, eleaffin=0.7465,         covrad=1.06, atmrad=1.23, vdwrad=1.8,         tboil=553.0, tmelt=317.3, density=1.82,         eleconfig='[Ne] 3s2 3p3',         oxistates='5*, 3, -3',         ionenergy=(             10.4867, 19.725, 30.18, 51.37, 65.023,             220.43, 263.22, 309.41, 371.73, 424.5,             479.57, 560.41, 611.85, 2816.943, 3069.762,         ),         isotopes={31: Isotope(30.97376199842, 1.0, 31)},     ),     Element(         16, 'S', 'Sulfur',         group=16, period=3, block='p', series=1,         mass=32.0648, eleneg=2.58, eleaffin=2.0771029,         covrad=1.02, atmrad=1.09, vdwrad=1.8,         tboil=717.82, tmelt=392.2, density=2.06,         eleconfig='[Ne] 3s2 3p4',         oxistates='6*, 4, 2, -2',         ionenergy=(             10.36, 23.33, 34.83, 47.3, 72.68,             88.049, 280.93, 328.23, 379.1, 447.09,             504.78, 564.65, 651.63, 707.14, 3223.836,             3494.099,         ),         isotopes={             32: Isotope(31.9720711744, 0.9499, 32),             33: Isotope(32.9714589098, 0.0075, 33),             34: Isotope(33.967867004, 0.0425, 34),             36: Isotope(35.96708071, 0.0001, 36),         },     ),     Element(         17, 'Cl', 'Chlorine',         group=17, period=3, block='p', series=6,         mass=35.4529, eleneg=3.16, eleaffin=3.612724,         covrad=0.99, atmrad=0.97, vdwrad=1.75,         tboil=239.18, tmelt=172.17, density=2.95,         eleconfig='[Ne] 3s2 3p5',         oxistates='7, 5, 3, 1, -1*',         ionenergy=(             12.9676, 23.81, 39.61, 53.46, 67.8,             98.03, 114.193, 348.28, 400.05, 455.62,             529.97, 591.97, 656.69, 749.75, 809.39,             3658.425, 3946.193,         ),         isotopes={             35: Isotope(34.968852682, 0.7576, 35),             37: Isotope(36.965902602, 0.2424, 37),         },     ),     Element(         18, 'Ar', 'Argon',         group=18, period=3, block='p', series=2,         mass=39.948, eleneg=0.0, eleaffin=0.0,         covrad=0.98, atmrad=0.88, vdwrad=1.88,         tboil=87.45, tmelt=83.95, density=1.66,         eleconfig='[Ne] 3s2 3p6',         oxistates='*',         ionenergy=(             15.7596, 27.629, 40.74, 59.81, 75.02,             91.007, 124.319, 143.456, 422.44, 478.68,             538.95, 618.24, 686.09, 755.73, 854.75,             918.0, 4120.778, 4426.114,         ),         isotopes={             36: Isotope(35.967545105, 0.003336, 36),             38: Isotope(37.96273211, 0.000629, 38),             40: Isotope(39.9623831237, 0.996035, 40),         },     ),     Element(         19, 'K', 'Potassium',         group=1, period=4, block='s', series=3,         mass=39.0983, eleneg=0.82, eleaffin=0.501459,         covrad=2.03, atmrad=2.77, vdwrad=2.75,         tboil=1033.0, tmelt=336.8, density=0.86,         eleconfig='[Ar] 4s',         oxistates='1*',         ionenergy=(             4.3407, 31.625, 45.72, 60.91, 82.66,             100.0, 117.56, 154.86, 175.814, 503.44,             564.13, 629.09, 714.02, 787.13, 861.77,             968.0, 1034.0, 4610.955, 4933.931,         ),         isotopes={             39: Isotope(38.9637064864, 0.932581, 39),             40: Isotope(39.963998166, 0.000117, 40),             41: Isotope(40.9618252579, 0.067302, 41),         },     ),     Element(         20, 'Ca', 'Calcium',         group=2, period=4, block='s', series=4,         mass=40.078, eleneg=1.0, eleaffin=0.02455,         covrad=1.74, atmrad=2.23, vdwrad=0.0,         tboil=1757.0, tmelt=1112.0, density=1.54,         eleconfig='[Ar] 4s2',         oxistates='2*',         ionenergy=(             6.1132, 11.71, 50.908, 67.1, 84.41,             108.78, 127.7, 147.24, 188.54, 211.27,             591.25, 656.39, 726.03, 816.61, 895.12,             974.0, 1087.0, 1157.0, 5129.045, 5469.738,         ),         isotopes={             40: Isotope(39.962590863, 0.96941, 40),             42: Isotope(41.95861783, 0.00647, 42),             43: Isotope(42.95876644, 0.00135, 43),             44: Isotope(43.95548156, 0.02086, 44),             46: Isotope(45.953689, 4e-05, 46),             48: Isotope(47.95252276, 0.00187, 48),         },     ),     Element(         21, 'Sc', 'Scandium',         group=3, period=4, block='d', series=8,         mass=44.955908, eleneg=1.36, eleaffin=0.188,         covrad=1.44, atmrad=2.09, vdwrad=0.0,         tboil=3109.0, tmelt=1814.0, density=2.99,         eleconfig='[Ar] 3d 4s2',         oxistates='3*',         ionenergy=(             6.5615, 12.8, 24.76, 73.47, 91.66,             110.1, 138.0, 158.7, 180.02, 225.32,             249.8, 685.89, 755.47, 829.79, 926.0,         ),         isotopes={45: Isotope(44.95590828, 1.0, 45)},     ),     Element(         22, 'Ti', 'Titanium',         group=4, period=4, block='d', series=8,         mass=47.867, eleneg=1.54, eleaffin=0.084,         covrad=1.32, atmrad=2.0, vdwrad=0.0,         tboil=3560.0, tmelt=1935.0, density=4.51,         eleconfig='[Ar] 3d2 4s2',         oxistates='4*, 3',         ionenergy=(             6.8281, 13.58, 27.491, 43.266, 99.22,             119.36, 140.8, 168.5, 193.5, 215.91,             265.23, 291.497, 787.33, 861.33,         ),         isotopes={             46: Isotope(45.95262772, 0.0825, 46),             47: Isotope(46.95175879, 0.0744, 47),             48: Isotope(47.94794198, 0.7372, 48),             49: Isotope(48.94786568, 0.0541, 49),             50: Isotope(49.94478689, 0.0518, 50),         },     ),     Element(         23, 'V', 'Vanadium',         group=5, period=4, block='d', series=8,         mass=50.9415, eleneg=1.63, eleaffin=0.525,         covrad=1.22, atmrad=1.92, vdwrad=0.0,         tboil=3650.0, tmelt=2163.0, density=6.09,         eleconfig='[Ar] 3d3 4s2',         oxistates='5*, 4, 3, 2, 0',         ionenergy=(             6.7462, 14.65, 29.31, 46.707, 65.23,             128.12, 150.17, 173.7, 205.8, 230.5,             255.04, 308.25, 336.267, 895.58, 974.02,         ),         isotopes={             50: Isotope(49.94715601, 0.0025, 50),             51: Isotope(50.94395704, 0.9975, 51),         },     ),     Element(         24, 'Cr', 'Chromium',         group=6, period=4, block='d', series=8,         mass=51.9961, eleneg=1.66, eleaffin=0.67584,         covrad=1.18, atmrad=1.85, vdwrad=0.0,         tboil=2945.0, tmelt=2130.0, density=7.14,         eleconfig='[Ar] 3d5 4s',         oxistates='6, 3*, 2, 0',         ionenergy=(             6.7665, 16.5, 30.96, 49.1, 69.3,             90.56, 161.1, 184.7, 209.3, 244.4,             270.8, 298.0, 355.0, 384.3, 1010.64,         ),         isotopes={             50: Isotope(49.94604183, 0.04345, 50),             52: Isotope(51.94050623, 0.83789, 52),             53: Isotope(52.94064815, 0.09501, 53),             54: Isotope(53.93887916, 0.02365, 54),         },     ),     Element(         25, 'Mn', 'Manganese',         group=7, period=4, block='d', series=8,         mass=54.938044, eleneg=1.55, eleaffin=0.0,         covrad=1.17, atmrad=1.79, vdwrad=0.0,         tboil=2235.0, tmelt=1518.0, density=7.44,         eleconfig='[Ar] 3d5 4s2',         oxistates='7, 6, 4, 3, 2*, 0, -1',         ionenergy=(             7.434, 15.64, 33.667, 51.2, 72.4,             95.0, 119.27, 196.46, 221.8, 248.3,             286.0, 314.4, 343.6, 404.0, 435.3,             1136.2,         ),         isotopes={55: Isotope(54.93804391, 1.0, 55)},     ),     Element(         26, 'Fe', 'Iron',         group=8, period=4, block='d', series=8,         mass=55.845, eleneg=1.83, eleaffin=0.151,         covrad=1.17, atmrad=1.72, vdwrad=0.0,         tboil=3023.0, tmelt=1808.0, density=7.874,         eleconfig='[Ar] 3d6 4s2',         oxistates='6, 3*, 2, 0, -2',         ionenergy=(             7.9024, 16.18, 30.651, 54.8, 75.0,             99.0, 125.0, 151.06, 235.04, 262.1,             290.4, 330.8, 361.0, 392.2, 457.0,             485.5, 1266.1,         ),         isotopes={             54: Isotope(53.93960899, 0.05845, 54),             56: Isotope(55.93493633, 0.91754, 56),             57: Isotope(56.93539284, 0.02119, 57),             58: Isotope(57.93327443, 0.00282, 58),         },     ),     Element(         27, 'Co', 'Cobalt',         group=9, period=4, block='d', series=8,         mass=58.933194, eleneg=1.88, eleaffin=0.6633,         covrad=1.16, atmrad=1.67, vdwrad=0.0,         tboil=3143.0, tmelt=1768.0, density=8.89,         eleconfig='[Ar] 3d7 4s2',         oxistates='3, 2*, 0, -1',         ionenergy=(             7.881, 17.06, 33.5, 51.3, 79.5,             102.0, 129.0, 157.0, 186.13, 276.0,             305.0, 336.0, 376.0, 411.0, 444.0,             512.0, 546.8, 1403.0,         ),         isotopes={59: Isotope(58.93319429, 1.0, 59)},     ),     Element(         28, 'Ni', 'Nickel',         group=10, period=4, block='d', series=8,         mass=58.6934, eleneg=1.91, eleaffin=1.15716,         covrad=1.15, atmrad=1.62, vdwrad=1.63,         tboil=3005.0, tmelt=1726.0, density=8.91,         eleconfig='[Ar] 3d8 4s2',         oxistates='3, 2*, 0',         ionenergy=(             7.6398, 18.168, 35.17, 54.9, 75.5,             108.0, 133.0, 162.0, 193.0, 224.5,             321.2, 352.0, 384.0, 430.0, 464.0,             499.0, 571.0, 607.2, 1547.0,         ),         isotopes={             58: Isotope(57.93534241, 0.68077, 58),             60: Isotope(59.93078588, 0.26223, 60),             61: Isotope(60.93105557, 0.011399, 61),             62: Isotope(61.92834537, 0.036346, 62),             64: Isotope(63.92796682, 0.009255, 64),         },     ),     Element(         29, 'Cu', 'Copper',         group=11, period=4, block='d', series=8,         mass=63.546, eleneg=1.9, eleaffin=1.23578,         covrad=1.17, atmrad=1.57, vdwrad=1.4,         tboil=2840.0, tmelt=1356.6, density=8.92,         eleconfig='[Ar] 3d10 4s',         oxistates='2*, 1',         ionenergy=(             7.7264, 20.292, 26.83, 55.2, 79.9,             103.0, 139.0, 166.0, 199.0, 232.0,             266.0, 368.8, 401.0, 435.0, 484.0,             520.0, 557.0, 633.0, 671.0, 1698.0,         ),         isotopes={             63: Isotope(62.92959772, 0.6915, 63),             65: Isotope(64.9277897, 0.3085, 65),         },     ),     Element(         30, 'Zn', 'Zinc',         group=12, period=4, block='d', series=8,         mass=65.38, eleneg=1.65, eleaffin=0.0,         covrad=1.25, atmrad=1.53, vdwrad=1.39,         tboil=1180.0, tmelt=692.73, density=7.14,         eleconfig='[Ar] 3d10 4s2',         oxistates='2*',         ionenergy=(             9.3942, 17.964, 39.722, 59.4, 82.6,             108.0, 134.0, 174.0, 203.0, 238.0,             274.0, 310.8, 419.7, 454.0, 490.0,             542.0, 579.0, 619.0, 698.8, 738.0,             1856.0,         ),         isotopes={             64: Isotope(63.92914201, 0.4917, 64),             66: Isotope(65.92603381, 0.2773, 66),             67: Isotope(66.92712775, 0.0404, 67),             68: Isotope(67.92484455, 0.1845, 68),             70: Isotope(69.9253192, 0.0061, 70),         },     ),     Element(         31, 'Ga', 'Gallium',         group=13, period=4, block='p', series=7,         mass=69.723, eleneg=1.81, eleaffin=0.41,         covrad=1.26, atmrad=1.81, vdwrad=1.87,         tboil=2478.0, tmelt=302.92, density=5.91,         eleconfig='[Ar] 3d10 4s2 4p',         oxistates='3*',         ionenergy=(5.9993, 20.51, 30.71, 64.0),         isotopes={             69: Isotope(68.9255735, 0.60108, 69),             71: Isotope(70.92470258, 0.39892, 71),         },     ),     Element(         32, 'Ge', 'Germanium',         group=14, period=4, block='p', series=5,         mass=72.63, eleneg=2.01, eleaffin=1.232712,         covrad=1.22, atmrad=1.52, vdwrad=0.0,         tboil=3107.0, tmelt=1211.5, density=5.32,         eleconfig='[Ar] 3d10 4s2 4p2',         oxistates='4*',         ionenergy=(7.8994, 15.934, 34.22, 45.71, 93.5),         isotopes={             70: Isotope(69.92424875, 0.2057, 70),             72: Isotope(71.922075826, 0.2745, 72),             73: Isotope(72.923458956, 0.0775, 73),             74: Isotope(73.921177761, 0.365, 74),             76: Isotope(75.921402726, 0.0773, 76),         },     ),     Element(         33, 'As', 'Arsenic',         group=15, period=4, block='p', series=5,         mass=74.921595, eleneg=2.18, eleaffin=0.814,         covrad=1.2, atmrad=1.33, vdwrad=1.85,         tboil=876.0, tmelt=1090.0, density=5.72,         eleconfig='[Ar] 3d10 4s2 4p3',         oxistates='5, 3*, -3',         ionenergy=(             9.7886, 18.633, 28.351, 50.13, 62.63,             127.6,         ),         isotopes={75: Isotope(74.92159457, 1.0, 75)},     ),     Element(         34, 'Se', 'Selenium',         group=16, period=4, block='p', series=1,         mass=78.971, eleneg=2.55, eleaffin=2.02067,         covrad=1.16, atmrad=1.22, vdwrad=1.9,         tboil=958.0, tmelt=494.0, density=4.82,         eleconfig='[Ar] 3d10 4s2 4p4',         oxistates='6, 4*, -2',         ionenergy=(             9.7524, 21.9, 30.82, 42.944, 68.3,             81.7, 155.4,         ),         isotopes={             74: Isotope(73.922475934, 0.0089, 74),             76: Isotope(75.919213704, 0.0937, 76),             77: Isotope(76.919914154, 0.0763, 77),             78: Isotope(77.91730928, 0.2377, 78),             80: Isotope(79.9165218, 0.4961, 80),             82: Isotope(81.9166995, 0.0873, 82),         },     ),     Element(         35, 'Br', 'Bromine',         group=17, period=4, block='p', series=6,         mass=79.9035, eleneg=2.96, eleaffin=3.363588,         covrad=1.14, atmrad=1.12, vdwrad=1.85,         tboil=331.85, tmelt=265.95, density=3.14,         eleconfig='[Ar] 3d10 4s2 4p5',         oxistates='7, 5, 3, 1, -1*',         ionenergy=(             11.8138, 21.8, 36.0, 47.3, 59.7,             88.6, 103.0, 192.8,         ),         isotopes={             79: Isotope(78.9183376, 0.5069, 79),             81: Isotope(80.9162897, 0.4931, 81),         },     ),     Element(         36, 'Kr', 'Krypton',         group=18, period=4, block='p', series=2,         mass=83.798, eleneg=0.0, eleaffin=0.0,         covrad=1.12, atmrad=1.03, vdwrad=2.02,         tboil=120.85, tmelt=116.0, density=4.48,         eleconfig='[Ar] 3d10 4s2 4p6',         oxistates='2*',         ionenergy=(             13.9996, 24.359, 36.95, 52.5, 64.7,             78.5, 110.0, 126.0, 230.39,         ),         isotopes={             78: Isotope(77.92036494, 0.00355, 78),             80: Isotope(79.91637808, 0.02286, 80),             82: Isotope(81.91348273, 0.11593, 82),             83: Isotope(82.91412716, 0.115, 83),             84: Isotope(83.9114977282, 0.56987, 84),             86: Isotope(85.9106106269, 0.17279, 86),         },     ),     Element(         37, 'Rb', 'Rubidium',         group=1, period=5, block='s', series=3,         mass=85.4678, eleneg=0.82, eleaffin=0.485916,         covrad=2.16, atmrad=2.98, vdwrad=0.0,         tboil=961.0, tmelt=312.63, density=1.53,         eleconfig='[Kr] 5s',         oxistates='1*',         ionenergy=(             4.1771, 27.28, 40.0, 52.6, 71.0,             84.4, 99.2, 136.0, 150.0, 277.1,         ),         isotopes={             85: Isotope(84.9117897379, 0.7217, 85),             87: Isotope(86.909180531, 0.2783, 87),         },     ),     Element(         38, 'Sr', 'Strontium',         group=2, period=5, block='s', series=4,         mass=87.62, eleneg=0.95, eleaffin=0.05206,         covrad=1.91, atmrad=2.45, vdwrad=0.0,         tboil=1655.0, tmelt=1042.0, density=2.63,         eleconfig='[Kr] 5s2',         oxistates='2*',         ionenergy=(             5.6949, 11.03, 43.6, 57.0, 71.6,             90.8, 106.0, 122.3, 162.0, 177.0,             324.1,         ),         isotopes={             84: Isotope(83.9134191, 0.0056, 84),             86: Isotope(85.9092606, 0.0986, 86),             87: Isotope(86.9088775, 0.07, 87),             88: Isotope(87.9056125, 0.8258, 88),         },     ),     Element(         39, 'Y', 'Yttrium',         group=3, period=5, block='d', series=8,         mass=88.90584, eleneg=1.22, eleaffin=0.307,         covrad=1.62, atmrad=2.27, vdwrad=0.0,         tboil=3611.0, tmelt=1795.0, density=4.47,         eleconfig='[Kr] 4d 5s2',         oxistates='3*',         ionenergy=(             6.2173, 12.24, 20.52, 61.8, 77.0,             93.0, 116.0, 129.0, 146.52, 191.0,             206.0, 374.0,         ),         isotopes={89: Isotope(88.9058403, 1.0, 89)},     ),     Element(         40, 'Zr', 'Zirconium',         group=4, period=5, block='d', series=8,         mass=91.224, eleneg=1.33, eleaffin=0.426,         covrad=1.45, atmrad=2.16, vdwrad=0.0,         tboil=4682.0, tmelt=2128.0, density=6.51,         eleconfig='[Kr] 4d2 5s2',         oxistates='4*',         ionenergy=(6.6339, 13.13, 22.99, 34.34, 81.5),         isotopes={             90: Isotope(89.9046977, 0.5145, 90),             91: Isotope(90.9056396, 0.1122, 91),             92: Isotope(91.9050347, 0.1715, 92),             94: Isotope(93.9063108, 0.1738, 94),             96: Isotope(95.9082714, 0.028, 96),         },     ),     Element(         41, 'Nb', 'Niobium',         group=5, period=5, block='d', series=8,         mass=92.90637, eleneg=1.6, eleaffin=0.893,         covrad=1.34, atmrad=2.08, vdwrad=0.0,         tboil=5015.0, tmelt=2742.0, density=8.58,         eleconfig='[Kr] 4d4 5s',         oxistates='5*, 3',         ionenergy=(             6.7589, 14.32, 25.04, 38.3, 50.55,             102.6, 125.0,         ),         isotopes={93: Isotope(92.906373, 1.0, 93)},     ),     Element(         42, 'Mo', 'Molybdenum',         group=6, period=5, block='d', series=8,         mass=95.95, eleneg=2.16, eleaffin=0.7472,         covrad=1.3, atmrad=2.01, vdwrad=0.0,         tboil=4912.0, tmelt=2896.0, density=10.28,         eleconfig='[Kr] 4d5 5s',         oxistates='6*, 5, 4, 3, 2, 0',         ionenergy=(             7.0924, 16.15, 27.16, 46.4, 61.2,             68.0, 126.8, 153.0,         ),         isotopes={             92: Isotope(91.90680796, 0.1453, 92),             94: Isotope(93.9050849, 0.0915, 94),             95: Isotope(94.90583877, 0.1584, 95),             96: Isotope(95.90467612, 0.1667, 96),             97: Isotope(96.90601812, 0.096, 97),             98: Isotope(97.90540482, 0.2439, 98),             100: Isotope(99.9074718, 0.0982, 100),         },     ),     Element(         43, 'Tc', 'Technetium',         group=7, period=5, block='d', series=8,         mass=97.9072, eleneg=1.9, eleaffin=0.55,         covrad=1.27, atmrad=1.95, vdwrad=0.0,         tboil=4538.0, tmelt=2477.0, density=11.49,         eleconfig='[Kr] 4d5 5s2',         oxistates='7*',         ionenergy=(7.28, 15.26, 29.54),         isotopes={98: Isotope(97.9072124, 1.0, 98)},     ),     Element(         44, 'Ru', 'Ruthenium',         group=8, period=5, block='d', series=8,         mass=101.07, eleneg=2.2, eleaffin=1.04638,         covrad=1.25, atmrad=1.89, vdwrad=0.0,         tboil=4425.0, tmelt=2610.0, density=12.45,         eleconfig='[Kr] 4d7 5s',         oxistates='8, 6, 4*, 3*, 2, 0, -2',         ionenergy=(7.3605, 16.76, 28.47),         isotopes={             96: Isotope(95.90759025, 0.0554, 96),             98: Isotope(97.9052868, 0.0187, 98),             99: Isotope(98.9059341, 0.1276, 99),             100: Isotope(99.9042143, 0.126, 100),             101: Isotope(100.9055769, 0.1706, 101),             102: Isotope(101.9043441, 0.3155, 102),             104: Isotope(103.9054275, 0.1862, 104),         },     ),     Element(         45, 'Rh', 'Rhodium',         group=9, period=5, block='d', series=8,         mass=102.9055, eleneg=2.28, eleaffin=1.14289,         covrad=1.25, atmrad=1.83, vdwrad=0.0,         tboil=3970.0, tmelt=2236.0, density=12.41,         eleconfig='[Kr] 4d8 5s',         oxistates='5, 4, 3*, 1*, 2, 0',         ionenergy=(7.4589, 18.08, 31.06),         isotopes={103: Isotope(102.905498, 1.0, 103)},     ),     Element(         46, 'Pd', 'Palladium',         group=10, period=5, block='d', series=8,         mass=106.42, eleneg=2.2, eleaffin=0.56214,         covrad=1.28, atmrad=1.79, vdwrad=1.63,         tboil=3240.0, tmelt=1825.0, density=12.02,         eleconfig='[Kr] 4d10',         oxistates='4, 2*, 0',         ionenergy=(8.3369, 19.43, 32.93),         isotopes={             102: Isotope(101.9056022, 0.0102, 102),             104: Isotope(103.9040305, 0.1114, 104),             105: Isotope(104.9050796, 0.2233, 105),             106: Isotope(105.9034804, 0.2733, 106),             108: Isotope(107.9038916, 0.2646, 108),             110: Isotope(109.9051722, 0.1172, 110),         },     ),     Element(         47, 'Ag', 'Silver',         group=11, period=5, block='d', series=8,         mass=107.8682, eleneg=1.93, eleaffin=1.30447,         covrad=1.34, atmrad=1.75, vdwrad=1.72,         tboil=2436.0, tmelt=1235.1, density=10.49,         eleconfig='[Kr] 4d10 5s',         oxistates='2, 1*',         ionenergy=(7.5762, 21.49, 34.83),         isotopes={             107: Isotope(106.9050916, 0.51839, 107),             109: Isotope(108.9047553, 0.48161, 109),         },     ),     Element(         48, 'Cd', 'Cadmium',         group=12, period=5, block='d', series=8,         mass=112.414, eleneg=1.69, eleaffin=0.0,         covrad=1.48, atmrad=1.71, vdwrad=1.58,         tboil=1040.0, tmelt=594.26, density=8.64,         eleconfig='[Kr] 4d10 5s2',         oxistates='2*',         ionenergy=(8.9938, 16.908, 37.48),         isotopes={             106: Isotope(105.9064599, 0.0125, 106),             108: Isotope(107.9041834, 0.0089, 108),             110: Isotope(109.90300661, 0.1249, 110),             111: Isotope(110.90418287, 0.128, 111),             112: Isotope(111.90276287, 0.2413, 112),             113: Isotope(112.90440813, 0.1222, 113),             114: Isotope(113.90336509, 0.2873, 114),             116: Isotope(115.90476315, 0.0749, 116),         },     ),     Element(         49, 'In', 'Indium',         group=13, period=5, block='p', series=7,         mass=114.818, eleneg=1.78, eleaffin=0.404,         covrad=1.44, atmrad=2.0, vdwrad=1.93,         tboil=2350.0, tmelt=429.78, density=7.31,         eleconfig='[Kr] 4d10 5s2 5p',         oxistates='3*',         ionenergy=(5.7864, 18.869, 28.03, 55.45),         isotopes={             113: Isotope(112.90406184, 0.0429, 113),             115: Isotope(114.903878776, 0.9571, 115),         },     ),     Element(         50, 'Sn', 'Tin',         group=14, period=5, block='p', series=7,         mass=118.71, eleneg=1.96, eleaffin=1.112066,         covrad=1.41, atmrad=1.72, vdwrad=2.17,         tboil=2876.0, tmelt=505.12, density=7.29,         eleconfig='[Kr] 4d10 5s2 5p2',         oxistates='4*, 2*',         ionenergy=(7.3439, 14.632, 30.502, 40.734, 72.28),         isotopes={             112: Isotope(111.90482387, 0.0097, 112),             114: Isotope(113.9027827, 0.0066, 114),             115: Isotope(114.903344699, 0.0034, 115),             116: Isotope(115.9017428, 0.1454, 116),             117: Isotope(116.90295398, 0.0768, 117),             118: Isotope(117.90160657, 0.2422, 118),             119: Isotope(118.90331117, 0.0859, 119),             120: Isotope(119.90220163, 0.3258, 120),             122: Isotope(121.9034438, 0.0463, 122),             124: Isotope(123.9052766, 0.0579, 124),         },     ),     Element(         51, 'Sb', 'Antimony',         group=15, period=5, block='p', series=5,         mass=121.76, eleneg=2.05, eleaffin=1.047401,         covrad=1.4, atmrad=1.53, vdwrad=0.0,         tboil=1860.0, tmelt=903.91, density=6.69,         eleconfig='[Kr] 4d10 5s2 5p3',         oxistates='5, 3*, -3',         ionenergy=(             8.6084, 16.53, 25.3, 44.2, 56.0,             108.0,         ),         isotopes={             121: Isotope(120.903812, 0.5721, 121),             123: Isotope(122.9042132, 0.4279, 123),         },     ),     Element(         52, 'Te', 'Tellurium',         group=16, period=5, block='p', series=5,         mass=127.6, eleneg=2.1, eleaffin=1.970875,         covrad=1.36, atmrad=1.42, vdwrad=2.06,         tboil=1261.0, tmelt=722.72, density=6.25,         eleconfig='[Kr] 4d10 5s2 5p4',         oxistates='6, 4*, -2',         ionenergy=(             9.0096, 18.6, 27.96, 37.41, 58.75,             70.7, 137.0,         ),         isotopes={             120: Isotope(119.9040593, 0.0009, 120),             122: Isotope(121.9030435, 0.0255, 122),             123: Isotope(122.9042698, 0.0089, 123),             124: Isotope(123.9028171, 0.0474, 124),             125: Isotope(124.9044299, 0.0707, 125),             126: Isotope(125.9033109, 0.1884, 126),             128: Isotope(127.90446128, 0.3174, 128),             130: Isotope(129.906222748, 0.3408, 130),         },     ),     Element(         53, 'I', 'Iodine',         group=17, period=5, block='p', series=6,         mass=126.90447, eleneg=2.66, eleaffin=3.059038,         covrad=1.33, atmrad=1.32, vdwrad=1.98,         tboil=457.5, tmelt=386.7, density=4.94,         eleconfig='[Kr] 4d10 5s2 5p5',         oxistates='7, 5, 1, -1*',         ionenergy=(10.4513, 19.131, 33.0),         isotopes={127: Isotope(126.9044719, 1.0, 127)},     ),     Element(         54, 'Xe', 'Xenon',         group=18, period=5, block='p', series=2,         mass=131.293, eleneg=0.0, eleaffin=0.0,         covrad=1.31, atmrad=1.24, vdwrad=2.16,         tboil=165.1, tmelt=161.39, density=4.49,         eleconfig='[Kr] 4d10 5s2 5p6',         oxistates='2, 4, 6',         ionenergy=(12.1298, 21.21, 32.1),         isotopes={             124: Isotope(123.905892, 0.000952, 124),             126: Isotope(125.9042983, 0.00089, 126),             128: Isotope(127.903531, 0.019102, 128),             129: Isotope(128.9047808611, 0.264006, 129),             130: Isotope(129.903509349, 0.04071, 130),             131: Isotope(130.90508406, 0.212324, 131),             132: Isotope(131.9041550856, 0.269086, 132),             134: Isotope(133.90539466, 0.104357, 134),             136: Isotope(135.907214484, 0.088573, 136),         },     ),     Element(         55, 'Cs', 'Caesium',         group=1, period=6, block='s', series=3,         mass=132.90545196, eleneg=0.79, eleaffin=0.471626,         covrad=2.35, atmrad=3.34, vdwrad=0.0,         tboil=944.0, tmelt=301.54, density=1.9,         eleconfig='[Xe] 6s',         oxistates='1*',         ionenergy=(3.8939, 25.1),         isotopes={133: Isotope(132.905451961, 1.0, 133)},     ),     Element(         56, 'Ba', 'Barium',         group=2, period=6, block='s', series=4,         mass=137.327, eleneg=0.89, eleaffin=0.14462,         covrad=1.98, atmrad=2.78, vdwrad=0.0,         tboil=2078.0, tmelt=1002.0, density=3.65,         eleconfig='[Xe] 6s2',         oxistates='2*',         ionenergy=(5.2117, 100.004),         isotopes={             130: Isotope(129.9063207, 0.00106, 130),             132: Isotope(131.9050611, 0.00101, 132),             134: Isotope(133.90450818, 0.02417, 134),             135: Isotope(134.90568838, 0.06592, 135),             136: Isotope(135.90457573, 0.07854, 136),             137: Isotope(136.90582714, 0.11232, 137),             138: Isotope(137.905247, 0.71698, 138),         },     ),     Element(         57, 'La', 'Lanthanum',         group=3, period=6, block='f', series=9,         mass=138.90547, eleneg=1.1, eleaffin=0.47,         covrad=1.69, atmrad=2.74, vdwrad=0.0,         tboil=3737.0, tmelt=1191.0, density=6.16,         eleconfig='[Xe] 5d 6s2',         oxistates='3*',         ionenergy=(5.5769, 11.06, 19.175),         isotopes={             138: Isotope(137.9071149, 0.0008881, 138),             139: Isotope(138.9063563, 0.9991119, 139),         },     ),     Element(         58, 'Ce', 'Cerium',         group=3, period=6, block='f', series=9,         mass=140.116, eleneg=1.12, eleaffin=0.5,         covrad=1.65, atmrad=2.7, vdwrad=0.0,         tboil=3715.0, tmelt=1071.0, density=6.77,         eleconfig='[Xe] 4f 5d 6s2',         oxistates='4, 3*',         ionenergy=(5.5387, 10.85, 20.2, 36.72),         isotopes={             136: Isotope(135.90712921, 0.00185, 136),             138: Isotope(137.905991, 0.00251, 138),             140: Isotope(139.9054431, 0.8845, 140),             142: Isotope(141.9092504, 0.11114, 142),         },     ),     Element(         59, 'Pr', 'Praseodymium',         group=3, period=6, block='f', series=9,         mass=140.90766, eleneg=1.13, eleaffin=0.5,         covrad=1.65, atmrad=2.67, vdwrad=0.0,         tboil=3785.0, tmelt=1204.0, density=6.48,         eleconfig='[Xe] 4f3 6s2',         oxistates='4, 3*',         ionenergy=(5.473, 10.55, 21.62, 38.95, 57.45),         isotopes={141: Isotope(140.9076576, 1.0, 141)},     ),     Element(         60, 'Nd', 'Neodymium',         group=3, period=6, block='f', series=9,         mass=144.242, eleneg=1.14, eleaffin=0.5,         covrad=1.64, atmrad=2.64, vdwrad=0.0,         tboil=3347.0, tmelt=1294.0, density=7.0,         eleconfig='[Xe] 4f4 6s2',         oxistates='3*',         ionenergy=(5.525, 10.72),         isotopes={             142: Isotope(141.907729, 0.27152, 142),             143: Isotope(142.90982, 0.12174, 143),             144: Isotope(143.910093, 0.23798, 144),             145: Isotope(144.9125793, 0.08293, 145),             146: Isotope(145.9131226, 0.17189, 146),             148: Isotope(147.9168993, 0.05756, 148),             150: Isotope(149.9209022, 0.05638, 150),         },     ),     Element(         61, 'Pm', 'Promethium',         group=3, period=6, block='f', series=9,         mass=144.9128, eleneg=1.13, eleaffin=0.5,         covrad=1.63, atmrad=2.62, vdwrad=0.0,         tboil=3273.0, tmelt=1315.0, density=7.22,         eleconfig='[Xe] 4f5 6s2',         oxistates='3*',         ionenergy=(5.582, 10.9),         isotopes={145: Isotope(144.9127559, 1.0, 145)},     ),     Element(         62, 'Sm', 'Samarium',         group=3, period=6, block='f', series=9,         mass=150.36, eleneg=1.17, eleaffin=0.5,         covrad=1.62, atmrad=2.59, vdwrad=0.0,         tboil=2067.0, tmelt=1347.0, density=7.54,         eleconfig='[Xe] 4f6 6s2',         oxistates='3*, 2',         ionenergy=(5.6437, 11.07),         isotopes={             144: Isotope(143.9120065, 0.0307, 144),             147: Isotope(146.9149044, 0.1499, 147),             148: Isotope(147.9148292, 0.1124, 148),             149: Isotope(148.9171921, 0.1382, 149),             150: Isotope(149.9172829, 0.0738, 150),             152: Isotope(151.9197397, 0.2675, 152),             154: Isotope(153.9222169, 0.2275, 154),         },     ),     Element(         63, 'Eu', 'Europium',         group=3, period=6, block='f', series=9,         mass=151.964, eleneg=1.2, eleaffin=0.5,         covrad=1.85, atmrad=2.56, vdwrad=0.0,         tboil=1800.0, tmelt=1095.0, density=5.25,         eleconfig='[Xe] 4f7 6s2',         oxistates='3*, 2',         ionenergy=(5.6704, 11.25),         isotopes={             151: Isotope(150.9198578, 0.4781, 151),             153: Isotope(152.921238, 0.5219, 153),         },     ),     Element(         64, 'Gd', 'Gadolinium',         group=3, period=6, block='f', series=9,         mass=157.25, eleneg=1.2, eleaffin=0.5,         covrad=1.61, atmrad=2.54, vdwrad=0.0,         tboil=3545.0, tmelt=1585.0, density=7.89,         eleconfig='[Xe] 4f7 5d 6s2',         oxistates='3*',         ionenergy=(6.1498, 12.1),         isotopes={             152: Isotope(151.9197995, 0.002, 152),             154: Isotope(153.9208741, 0.0218, 154),             155: Isotope(154.9226305, 0.148, 155),             156: Isotope(155.9221312, 0.2047, 156),             157: Isotope(156.9239686, 0.1565, 157),             158: Isotope(157.9241123, 0.2484, 158),             160: Isotope(159.9270624, 0.2186, 160),         },     ),     Element(         65, 'Tb', 'Terbium',         group=3, period=6, block='f', series=9,         mass=158.92535, eleneg=1.2, eleaffin=0.5,         covrad=1.59, atmrad=2.51, vdwrad=0.0,         tboil=3500.0, tmelt=1629.0, density=8.25,         eleconfig='[Xe] 4f9 6s2',         oxistates='4, 3*',         ionenergy=(5.8638, 11.52),         isotopes={159: Isotope(158.9253547, 1.0, 159)},     ),     Element(         66, 'Dy', 'Dysprosium',         group=3, period=6, block='f', series=9,         mass=162.5, eleneg=1.22, eleaffin=0.5,         covrad=1.59, atmrad=2.49, vdwrad=0.0,         tboil=2840.0, tmelt=1685.0, density=8.56,         eleconfig='[Xe] 4f10 6s2',         oxistates='3*',         ionenergy=(5.9389, 11.67),         isotopes={             156: Isotope(155.9242847, 0.00056, 156),             158: Isotope(157.9244159, 0.00095, 158),             160: Isotope(159.9252046, 0.02329, 160),             161: Isotope(160.9269405, 0.18889, 161),             162: Isotope(161.9268056, 0.25475, 162),             163: Isotope(162.9287383, 0.24896, 163),             164: Isotope(163.9291819, 0.2826, 164),         },     ),     Element(         67, 'Ho', 'Holmium',         group=3, period=6, block='f', series=9,         mass=164.93033, eleneg=1.23, eleaffin=0.5,         covrad=1.58, atmrad=2.47, vdwrad=0.0,         tboil=2968.0, tmelt=1747.0, density=8.78,         eleconfig='[Xe] 4f11 6s2',         oxistates='3*',         ionenergy=(6.0215, 11.8),         isotopes={165: Isotope(164.9303288, 1.0, 165)},     ),     Element(         68, 'Er', 'Erbium',         group=3, period=6, block='f', series=9,         mass=167.259, eleneg=1.24, eleaffin=0.5,         covrad=1.57, atmrad=2.45, vdwrad=0.0,         tboil=3140.0, tmelt=1802.0, density=9.05,         eleconfig='[Xe] 4f12 6s2',         oxistates='3*',         ionenergy=(6.1077, 11.93),         isotopes={             162: Isotope(161.9287884, 0.00139, 162),             164: Isotope(163.9292088, 0.01601, 164),             166: Isotope(165.9302995, 0.33503, 166),             167: Isotope(166.9320546, 0.22869, 167),             168: Isotope(167.9323767, 0.26978, 168),             170: Isotope(169.9354702, 0.1491, 170),         },     ),     Element(         69, 'Tm', 'Thulium',         group=3, period=6, block='f', series=9,         mass=168.93422, eleneg=1.25, eleaffin=0.5,         covrad=1.56, atmrad=2.42, vdwrad=0.0,         tboil=2223.0, tmelt=1818.0, density=9.32,         eleconfig='[Xe] 4f13 6s2',         oxistates='3*, 2',         ionenergy=(6.1843, 12.05, 23.71),         isotopes={169: Isotope(168.9342179, 1.0, 169)},     ),     Element(         70, 'Yb', 'Ytterbium',         group=3, period=6, block='f', series=9,         mass=173.054, eleneg=1.1, eleaffin=0.5,         covrad=1.74, atmrad=2.4, vdwrad=0.0,         tboil=1469.0, tmelt=1092.0, density=9.32,         eleconfig='[Xe] 4f14 6s2',         oxistates='3*, 2',         ionenergy=(6.2542, 12.17, 25.2),         isotopes={             168: Isotope(167.9338896, 0.00123, 168),             170: Isotope(169.9347664, 0.02982, 170),             171: Isotope(170.9363302, 0.1409, 171),             172: Isotope(171.9363859, 0.2168, 172),             173: Isotope(172.9382151, 0.16103, 173),             174: Isotope(173.9388664, 0.32026, 174),             176: Isotope(175.9425764, 0.12996, 176),         },     ),     Element(         71, 'Lu', 'Lutetium',         group=3, period=6, block='d', series=9,         mass=174.9668, eleneg=1.27, eleaffin=0.5,         covrad=1.56, atmrad=2.25, vdwrad=0.0,         tboil=3668.0, tmelt=1936.0, density=9.84,         eleconfig='[Xe] 4f14 5d 6s2',         oxistates='3*',         ionenergy=(5.4259, 13.9),         isotopes={             175: Isotope(174.9407752, 0.97401, 175),             176: Isotope(175.9426897, 0.02599, 176),         },     ),     Element(         72, 'Hf', 'Hafnium',         group=4, period=6, block='d', series=8,         mass=178.49, eleneg=1.3, eleaffin=0.0,         covrad=1.44, atmrad=2.16, vdwrad=0.0,         tboil=4875.0, tmelt=2504.0, density=13.31,         eleconfig='[Xe] 4f14 5d2 6s2',         oxistates='4*',         ionenergy=(6.8251, 14.9, 23.3, 33.3),         isotopes={             174: Isotope(173.9400461, 0.0016, 174),             176: Isotope(175.9414076, 0.0526, 176),             177: Isotope(176.9432277, 0.186, 177),             178: Isotope(177.9437058, 0.2728, 178),             179: Isotope(178.9458232, 0.1362, 179),             180: Isotope(179.946557, 0.3508, 180),         },     ),     Element(         73, 'Ta', 'Tantalum',         group=5, period=6, block='d', series=8,         mass=180.94788, eleneg=1.5, eleaffin=0.322,         covrad=1.34, atmrad=2.09, vdwrad=0.0,         tboil=5730.0, tmelt=3293.0, density=16.68,         eleconfig='[Xe] 4f14 5d3 6s2',         oxistates='5*',         ionenergy=(7.5496,),         isotopes={             180: Isotope(179.9474648, 0.0001201, 180),             181: Isotope(180.9479958, 0.9998799, 181),         },     ),     Element(         74, 'W', 'Tungsten',         group=6, period=6, block='d', series=8,         mass=183.84, eleneg=2.36, eleaffin=0.815,         covrad=1.3, atmrad=2.02, vdwrad=0.0,         tboil=5825.0, tmelt=3695.0, density=19.26,         eleconfig='[Xe] 4f14 5d4 6s2',         oxistates='6*, 5, 4, 3, 2, 0',         ionenergy=(7.864,),         isotopes={             180: Isotope(179.9467108, 0.0012, 180),             182: Isotope(181.94820394, 0.265, 182),             183: Isotope(182.95022275, 0.1431, 183),             184: Isotope(183.95093092, 0.3064, 184),             186: Isotope(185.9543628, 0.2843, 186),         },     ),     Element(         75, 'Re', 'Rhenium',         group=7, period=6, block='d', series=8,         mass=186.207, eleneg=1.9, eleaffin=0.15,         covrad=1.28, atmrad=1.97, vdwrad=0.0,         tboil=5870.0, tmelt=3455.0, density=21.03,         eleconfig='[Xe] 4f14 5d5 6s2',         oxistates='7, 6, 4, 2, -1',         ionenergy=(7.8335,),         isotopes={             185: Isotope(184.9529545, 0.374, 185),             187: Isotope(186.9557501, 0.626, 187),         },     ),     Element(         76, 'Os', 'Osmium',         group=8, period=6, block='d', series=8,         mass=190.23, eleneg=2.2, eleaffin=1.0778,         covrad=1.26, atmrad=1.92, vdwrad=0.0,         tboil=5300.0, tmelt=3300.0, density=22.61,         eleconfig='[Xe] 4f14 5d6 6s2',         oxistates='8, 6, 4*, 3, 2, 0, -2',         ionenergy=(8.4382,),         isotopes={             184: Isotope(183.9524885, 0.0002, 184),             186: Isotope(185.953835, 0.0159, 186),             187: Isotope(186.9557474, 0.0196, 187),             188: Isotope(187.9558352, 0.1324, 188),             189: Isotope(188.9581442, 0.1615, 189),             190: Isotope(189.9584437, 0.2626, 190),             192: Isotope(191.961477, 0.4078, 192),         },     ),     Element(         77, 'Ir', 'Iridium',         group=9, period=6, block='d', series=8,         mass=192.217, eleneg=2.2, eleaffin=1.56436,         covrad=1.27, atmrad=1.87, vdwrad=0.0,         tboil=4700.0, tmelt=2720.0, density=22.65,         eleconfig='[Xe] 4f14 5d7 6s2',         oxistates='6, 4*, 3, 2, 1*, 0, -1',         ionenergy=(8.967,),         isotopes={             191: Isotope(190.9605893, 0.373, 191),             193: Isotope(192.9629216, 0.627, 193),         },     ),     Element(         78, 'Pt', 'Platinum',         group=10, period=6, block='d', series=8,         mass=195.084, eleneg=2.28, eleaffin=2.1251,         covrad=1.3, atmrad=1.83, vdwrad=1.75,         tboil=4100.0, tmelt=2042.1, density=21.45,         eleconfig='[Xe] 4f14 5d9 6s',         oxistates='4*, 2*, 0',         ionenergy=(8.9588, 18.563),         isotopes={             190: Isotope(189.9599297, 0.00012, 190),             192: Isotope(191.9610387, 0.00782, 192),             194: Isotope(193.9626809, 0.3286, 194),             195: Isotope(194.9647917, 0.3378, 195),             196: Isotope(195.96495209, 0.2521, 196),             198: Isotope(197.9678949, 0.07356, 198),         },     ),     Element(         79, 'Au', 'Gold',         group=11, period=6, block='d', series=8,         mass=196.966569, eleneg=2.54, eleaffin=2.30861,         covrad=1.34, atmrad=1.79, vdwrad=1.66,         tboil=3130.0, tmelt=1337.58, density=19.32,         eleconfig='[Xe] 4f14 5d10 6s',         oxistates='3*, 1',         ionenergy=(9.2255, 20.5),         isotopes={197: Isotope(196.96656879, 1.0, 197)},     ),     Element(         80, 'Hg', 'Mercury',         group=12, period=6, block='d', series=8,         mass=200.592, eleneg=2.0, eleaffin=0.0,         covrad=1.49, atmrad=1.76, vdwrad=0.0,         tboil=629.88, tmelt=234.31, density=13.55,         eleconfig='[Xe] 4f14 5d10 6s2',         oxistates='2*, 1',         ionenergy=(10.4375, 18.756, 34.2),         isotopes={             196: Isotope(195.9658326, 0.0015, 196),             198: Isotope(197.9667686, 0.0997, 198),             199: Isotope(198.96828064, 0.1687, 199),             200: Isotope(199.96832659, 0.231, 200),             201: Isotope(200.97030284, 0.1318, 201),             202: Isotope(201.9706434, 0.2986, 202),             204: Isotope(203.97349398, 0.0687, 204),         },     ),     Element(         81, 'Tl', 'Thallium',         group=13, period=6, block='p', series=7,         mass=204.3834, eleneg=2.04, eleaffin=0.377,         covrad=1.48, atmrad=2.08, vdwrad=1.96,         tboil=1746.0, tmelt=577.0, density=11.85,         eleconfig='[Xe] 4f14 5d10 6s2 6p',         oxistates='3, 1*',         ionenergy=(6.1082, 20.428, 29.83),         isotopes={             203: Isotope(202.9723446, 0.2952, 203),             205: Isotope(204.9744278, 0.7048, 205),         },     ),     Element(         82, 'Pb', 'Lead',         group=14, period=6, block='p', series=7,         mass=207.2, eleneg=2.33, eleaffin=0.364,         covrad=1.47, atmrad=1.81, vdwrad=2.02,         tboil=2023.0, tmelt=600.65, density=11.34,         eleconfig='[Xe] 4f14 5d10 6s2 6p2',         oxistates='4, 2*',         ionenergy=(7.4167, 15.032, 31.937, 42.32, 68.8),         isotopes={             204: Isotope(203.973044, 0.014, 204),             206: Isotope(205.9744657, 0.241, 206),             207: Isotope(206.9758973, 0.221, 207),             208: Isotope(207.9766525, 0.524, 208),         },     ),     Element(         83, 'Bi', 'Bismuth',         group=15, period=6, block='p', series=7,         mass=208.9804, eleneg=2.02, eleaffin=0.942363,         covrad=1.46, atmrad=1.63, vdwrad=0.0,         tboil=1837.0, tmelt=544.59, density=9.8,         eleconfig='[Xe] 4f14 5d10 6s2 6p3',         oxistates='5, 3*',         ionenergy=(             7.2855, 16.69, 25.56, 45.3, 56.0,             88.3,         ),         isotopes={209: Isotope(208.9803991, 1.0, 209)},     ),     Element(         84, 'Po', 'Polonium',         group=16, period=6, block='p', series=5,         mass=208.9824, eleneg=2.0, eleaffin=1.9,         covrad=1.46, atmrad=1.53, vdwrad=0.0,         tboil=0.0, tmelt=527.0, density=9.2,         eleconfig='[Xe] 4f14 5d10 6s2 6p4',         oxistates='6, 4*, 2',         ionenergy=(8.414,),         isotopes={209: Isotope(208.9824308, 1.0, 209)},     ),     Element(         85, 'At', 'Astatine',         group=17, period=6, block='p', series=6,         mass=209.9871, eleneg=2.2, eleaffin=2.8,         covrad=1.45, atmrad=1.43, vdwrad=0.0,         tboil=610.0, tmelt=575.0, density=0.0,         eleconfig='[Xe] 4f14 5d10 6s2 6p5',         oxistates='7, 5, 3, 1, -1*',         ionenergy=(),         isotopes={210: Isotope(209.9871479, 1.0, 210)},     ),     Element(         86, 'Rn', 'Radon',         group=18, period=6, block='p', series=2,         mass=222.0176, eleneg=0.0, eleaffin=0.0,         covrad=0.0, atmrad=1.34, vdwrad=0.0,         tboil=211.4, tmelt=202.0, density=9.23,         eleconfig='[Xe] 4f14 5d10 6s2 6p6',         oxistates='2*',         ionenergy=(10.7485,),         isotopes={222: Isotope(222.0175782, 1.0, 222)},     ),     Element(         87, 'Fr', 'Francium',         group=1, period=7, block='s', series=3,         mass=223.0197, eleneg=0.7, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=950.0, tmelt=300.0, density=0.0,         eleconfig='[Rn] 7s',         oxistates='1*',         ionenergy=(4.0727,),         isotopes={223: Isotope(223.019736, 1.0, 223)},     ),     Element(         88, 'Ra', 'Radium',         group=2, period=7, block='s', series=4,         mass=226.0254, eleneg=0.9, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=1413.0, tmelt=973.0, density=5.5,         eleconfig='[Rn] 7s2',         oxistates='2*',         ionenergy=(5.2784, 10.147),         isotopes={226: Isotope(226.0254103, 1.0, 226)},     ),     Element(         89, 'Ac', 'Actinium',         group=3, period=7, block='f', series=10,         mass=227.0278, eleneg=1.1, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=3470.0, tmelt=1324.0, density=10.07,         eleconfig='[Rn] 6d 7s2',         oxistates='3*',         ionenergy=(5.17, 12.1),         isotopes={227: Isotope(227.0277523, 1.0, 227)},     ),     Element(         90, 'Th', 'Thorium',         group=3, period=7, block='f', series=10,         mass=232.0377, eleneg=1.3, eleaffin=0.0,         covrad=1.65, atmrad=0.0, vdwrad=0.0,         tboil=5060.0, tmelt=2028.0, density=11.72,         eleconfig='[Rn] 6d2 7s2',         oxistates='4*',         ionenergy=(6.3067, 11.5, 20.0, 28.8),         isotopes={232: Isotope(232.0380558, 1.0, 232)},     ),     Element(         91, 'Pa', 'Protactinium',         group=3, period=7, block='f', series=10,         mass=231.03588, eleneg=1.5, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=4300.0, tmelt=1845.0, density=15.37,         eleconfig='[Rn] 5f2 6d 7s2',         oxistates='5*, 4',         ionenergy=(5.89,),         isotopes={231: Isotope(231.0358842, 1.0, 231)},     ),     Element(         92, 'U', 'Uranium',         group=3, period=7, block='f', series=10,         mass=238.02891, eleneg=1.38, eleaffin=0.0,         covrad=1.42, atmrad=0.0, vdwrad=1.86,         tboil=4407.0, tmelt=1408.0, density=18.97,         eleconfig='[Rn] 5f3 6d 7s2',         oxistates='6*, 5, 4, 3',         ionenergy=(6.1941,),         isotopes={             234: Isotope(234.0409523, 5.4e-05, 234),             235: Isotope(235.0439301, 0.007204, 235),             238: Isotope(238.0507884, 0.992742, 238),         },     ),     Element(         93, 'Np', 'Neptunium',         group=3, period=7, block='f', series=10,         mass=237.0482, eleneg=1.36, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=4175.0, tmelt=912.0, density=20.48,         eleconfig='[Rn] 5f4 6d 7s2',         oxistates='6, 5*, 4, 3',         ionenergy=(6.2657,),         isotopes={237: Isotope(237.0481736, 1.0, 237)},     ),     Element(         94, 'Pu', 'Plutonium',         group=3, period=7, block='f', series=10,         mass=244.0642, eleneg=1.28, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=3505.0, tmelt=913.0, density=19.74,         eleconfig='[Rn] 5f6 7s2',         oxistates='6, 5, 4*, 3',         ionenergy=(6.026,),         isotopes={244: Isotope(244.0642053, 1.0, 244)},     ),     Element(         95, 'Am', 'Americium',         group=3, period=7, block='f', series=10,         mass=243.0614, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=2880.0, tmelt=1449.0, density=13.67,         eleconfig='[Rn] 5f7 7s2',         oxistates='6, 5, 4, 3*',         ionenergy=(5.9738,),         isotopes={243: Isotope(243.0613813, 1.0, 243)},     ),     Element(         96, 'Cm', 'Curium',         group=3, period=7, block='f', series=10,         mass=247.0704, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=1620.0, density=13.51,         eleconfig='[Rn] 5f7 6d 7s2',         oxistates='4, 3*',         ionenergy=(5.9914,),         isotopes={247: Isotope(247.0703541, 1.0, 247)},     ),     Element(         97, 'Bk', 'Berkelium',         group=3, period=7, block='f', series=10,         mass=247.0703, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=1258.0, density=13.25,         eleconfig='[Rn] 5f9 7s2',         oxistates='4, 3*',         ionenergy=(6.1979,),         isotopes={247: Isotope(247.0703073, 1.0, 247)},     ),     Element(         98, 'Cf', 'Californium',         group=3, period=7, block='f', series=10,         mass=251.0796, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=1172.0, density=15.1,         eleconfig='[Rn] 5f10 7s2',         oxistates='4, 3*',         ionenergy=(6.2817,),         isotopes={251: Isotope(251.0795886, 1.0, 251)},     ),     Element(         99, 'Es', 'Einsteinium',         group=3, period=7, block='f', series=10,         mass=252.083, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=1130.0, density=0.0,         eleconfig='[Rn] 5f11 7s2',         oxistates='3*',         ionenergy=(6.42,),         isotopes={252: Isotope(252.08298, 1.0, 252)},     ),     Element(         100, 'Fm', 'Fermium',         group=3, period=7, block='f', series=10,         mass=257.0951, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=1800.0, density=0.0,         eleconfig='[Rn] 5f12 7s2',         oxistates='3*',         ionenergy=(6.5,),         isotopes={257: Isotope(257.0951061, 1.0, 257)},     ),     Element(         101, 'Md', 'Mendelevium',         group=3, period=7, block='f', series=10,         mass=258.0984, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=1100.0, density=0.0,         eleconfig='[Rn] 5f13 7s2',         oxistates='3*',         ionenergy=(6.58,),         isotopes={258: Isotope(258.0984315, 1.0, 258)},     ),     Element(         102, 'No', 'Nobelium',         group=3, period=7, block='f', series=10,         mass=259.101, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=1100.0, density=0.0,         eleconfig='[Rn] 5f14 7s2',         oxistates='3, 2*',         ionenergy=(6.65,),         isotopes={259: Isotope(259.10103, 1.0, 259)},     ),     Element(         103, 'Lr', 'Lawrencium',         group=3, period=7, block='d', series=10,         mass=262.1096, eleneg=1.3, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=1900.0, density=0.0,         eleconfig='[Rn] 5f14 6d 7s2',         oxistates='3*',         ionenergy=(4.9,),         isotopes={262: Isotope(262.10961, 1.0, 262)},     ),     Element(         104, 'Rf', 'Rutherfordium',         group=4, period=7, block='d', series=8,         mass=267.1218, eleneg=0.0, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=0.0, density=0.0,         eleconfig='[Rn] 5f14 6d2 7s2',         oxistates='*',         ionenergy=(6.0,),         isotopes={267: Isotope(267.12179, 1.0, 267)},     ),     Element(         105, 'Db', 'Dubnium',         group=5, period=7, block='d', series=8,         mass=268.1257, eleneg=0.0, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=0.0, density=0.0,         eleconfig='[Rn] 5f14 6d3 7s2',         oxistates='*',         ionenergy=(),         isotopes={268: Isotope(268.12567, 1.0, 268)},     ),     Element(         106, 'Sg', 'Seaborgium',         group=6, period=7, block='d', series=8,         mass=271.1339, eleneg=0.0, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=0.0, density=0.0,         eleconfig='[Rn] 5f14 6d4 7s2',         oxistates='*',         ionenergy=(),         isotopes={271: Isotope(271.13393, 1.0, 271)},     ),     Element(         107, 'Bh', 'Bohrium',         group=7, period=7, block='d', series=8,         mass=272.1383, eleneg=0.0, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=0.0, density=0.0,         eleconfig='[Rn] 5f14 6d5 7s2',         oxistates='*',         ionenergy=(),         isotopes={272: Isotope(272.13826, 1.0, 272)},     ),     Element(         108, 'Hs', 'Hassium',         group=8, period=7, block='d', series=8,         mass=270.1343, eleneg=0.0, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=0.0, density=0.0,         eleconfig='[Rn] 5f14 6d6 7s2',         oxistates='*',         ionenergy=(),         isotopes={270: Isotope(270.13429, 1.0, 270)},     ),     Element(         109, 'Mt', 'Meitnerium',         group=9, period=7, block='d', series=8,         mass=276.1516, eleneg=0.0, eleaffin=0.0,         covrad=0.0, atmrad=0.0, vdwrad=0.0,         tboil=0.0, tmelt=0.0, density=0.0,         eleconfig='[Rn] 5f14 6d7 7s2',         oxistates='*',         ionenergy=(),         isotopes={276: Isotope(276.15159, 1.0, 276)},     ), )

Collection of chemical elements with lookup by number, symbol, and name.

An ordered collection of Element instances with lookup by atomic number (int), chemical symbol (str), or element name (str).

Examples

>>> ELEMENTS[6]  # by atomic number
Element(6, 'C', 'Carbon', ...)
>>> ELEMENTS['C']  # by symbol
Element(6, 'C', 'Carbon', ...)
>>> ELEMENTS['Carbon']  # by name
Element(6, 'C', 'Carbon', ...)

molmass.elements.NEUTRON: Particle = Particle(name='Neutron', mass=1.00866491595, charge=0.0)

Neutron particle.

molmass.elements.POSITRON: Particle = Particle(name='Positron', mass=0.000548579909065, charge=1.602176634e-19)

Positron or antielectron particle.

molmass.elements.PROTON: Particle = Particle(name='Proton', mass=1.007276466621, charge=1.602176634e-19)

Proton particle.

molmass.web

molmass.web.main(*, form=None, url=None, open_browser=True, debug=DEBUG)

Run web application in local Flask or fallback CGI server.

Parameters:

• form (dict[str, str] | None) – Form data to use on first run.

• url (str | None) – URL at which the web application is served. The default is ‘http://127.0.0.1:5001/’.

• open_browser (bool) – Open url in web browser.

• debug (bool) – Enable debug mode.

Return type:

int

molmass.web.response(form, /, url, template=None, help=None, heads='')

Return HTML document from submitted web form.

Parameters:

• form (Any) – Flask.request.form or cgi.FieldStorage.

• url (str) – URL of web application.

• template (str | None) – HTML page template. The default is PAGE.

• help (str | None) – Help text. The default is HELP.

• heads (str) – Additional HTML page head sections.

Return type:

str