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    IsotopeAtomic mass (Da)Isotopic abundance (amount fraction)
    209Bi 208.980 40(1)1

    Bismuth is a monoisotopic element and its atomic weight is determined solely by its isotope 209Bi. The Commission last revised the standard atomic weight of bismuth in 2005 based on the latest Atomic Mass Evaluation by IUPAP.

    SOURCE  Atomic weights of the elements: Review 2000 by John R de Laeter et al. Pure Appl. Chem. 2003 (75) 683-800
    © IUPAC 2003


    Ar(Bi) = 208.980 40(1) since 2005

    The name derives from the German weisse masse for "white mass" from the colour of its oxides. The ancients did not distinguish bismuth from lead. The French chemist Claude-Francois Geoffroy showed that bismuth was distinct from lead in 1753.