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    Chromium

    IsotopeAtomic mass (Da)Isotopic abundance (amount fraction)
    50Cr 49.946 042(6)0.043 45(13)
    52Cr 51.940 506(4)0.837 89(18)
    53Cr 52.940 648(4)0.095 01(17)
    54Cr 53.938 879(4)0.023 65(7)

    In 1983 the Commission recommended the standard atomic weight of chromium to four decimal places, Ar(Cr) = 51.9961(6). Meanwhile, report isotope fractionation of chromium during chromate reduction, resulting in δ53CrSRM979 values in groundwater samples as high as +5.8 ‰ or Ar(Cr) = 51.9982, which is outside the current range of uncertainty of the standard atomic weight. Measurements of n(53Cr)/n(52Cr) can be expressed as δ53Cr values with respect to NIST SRM 979.

    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

    Chromium
    Ar(Cr) = 51.9961(6) since 1983

    The name derives from the Greek chroma for "colour", from the many coloured compounds of chromium. It was discovered in 1797 by the French chemist and pharmacist Nicolas-Louis Vauquelin, who also isolated chromium in 1798.

    Isotopic reference materials of chromium.