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    Platinum

    IsotopeAtomic mass (Da)Isotopic abundance (amount fraction)
    190Pt 189.959 93(4)0.000 12(2)
    192Pt 191.961 04(2)0.007 82(24)
    194Pt 193.962 681(6)0.328 64(410)
    195Pt 194.964 792(6)0.337 75(240)
    196Pt 195.964 952(6)0.252 11(340)
    198Pt 197.967 89(2)0.073 56(130)

    In 1961, the Commission recommended Ar(Pt) = 195.09(3) based on the determinations of the isotopic composition of this element. In 1979, the Commission corrected a small computational error by which Ar(Pt) was amended to 195.08(3). In 2005, the standard atomic weight of platinum was changed to Ar(Pt) = 195.084(9).

    The minor isotope, 190Pt, is radioactive with a very long half-life of 6.9(6)×1011 a. It does not affect the atomic weight of platinum even over geological time.

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

    CIAAW

    Platinum
    Ar(Pt) = 195.084(9) since 2005

    The name derives from the Spanish platina for "silver". In 1735, the Spanish astronomer Antonio de Ulloa found platinum in Peru, South America. In 1741, the English metallurgist Charles Wood found platinum from Colombia, South America. In 1750, the English physician William Brownrigg prepared purified platinum metal.

    Isotopic reference materials of platinum.