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Mass

periodictable.mass

Adds average mass for the elements:

  • mass, mass_units (u)

    The molar mass averaged over natural isotope abundance.

Adds mass and abundance information for isotopes:

  • mass, mass_units (u)

    The molar mass of the individual isotope.

  • abundance, abundance_units (%)

    Natural abundance for the isotope.

Atomic Weights and Isotopic Composition [1].

The atomic weights are available for elements 1 through 112, 114, & 116 and isotopic compositions or abundances are given when appropriate. The atomic weights data were published by Coplen [2] in Atomic Weights of the Elements 1999, (and include changes reported from the 2001 review in Chem. Int., 23, 179 (2001)) and the isotopic compositions data were published by Rosman [3] and Taylor [4] in Isotopic Compositions of the Elements 1997. The relative atomic masses of the isotopes data were published by Audi [5] and Wapstra [6] in the 1995 Update To The Atomic Mass Evaluation.

This data has been compiled from the above sources for the user’s convenience and does not represent a critical evaluation by the NIST Physics Laboratory. http://physics.nist.gov/PhysRefData/Compositions/

Neutron mass from NIST Reference on Constants, Units, and Uncertainty http://physics.nist.gov/cuu/index.html

periodictable.mass.abundance(isotope)

Natural abundance.

Parameters:

isotope : Isotope

Returns:

abundance : float | %

Reference:

Coursey. J. S., Schwab. D. J, and Dragoset. R. A., NIST Atomic Weights and Isotopic Composition Database.

periodictable.mass.init(table, reload=False)

Add mass attribute to period table elements and isotopes

periodictable.mass.mass(isotope)

Atomic weight.

Parameters:

isotope : Isotope

Returns:
massfloat | u

Atomic weight of the element.

Reference:

Coursey. J. S., Schwab. D. J, and Dragoset. R. A., NIST Atomic Weights and Isotopic Composition Database.