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    IsotopeAtomic mass (Da)Isotopic abundance (amount fraction)
    96Ru 95.907 589(1)0.0554(14)
    98Ru 97.905 29(5)0.0187(3)
    99Ru 98.905 930(3)0.1276(14)
    100Ru 99.904 211(3)0.1260(7)
    101Ru 100.905 573(3)0.1706(2)
    102Ru 101.904 340(3)0.3155(14)
    104Ru 103.905 43(2)0.1862(27)

    In its 1961 report, the Commission changed the recommended atomic-weight value, Ar(Ru), from 101.1 to 101.07. In 1969, an uncertainty of 0.03 was assigned to that value. In view of the excellent agreement between the reported data, the Commission recommended in 1983 a reduction in the uncertainty of the standard atomic weight to Ar(Ru) = 101.07(2). The annotation "g" refers to anomalous occurrences at the Oklo natural nuclear reactor.

    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(Ru) = 101.07(2) since 1983

    The name derives from the Latin ruthenia for the old name of Russia. It was discovered in a crude platinum ore by the Russian chemist Gottfried Wilhelm Osann in 1828. Osann thought that he had found three new metals in the sample, pluranium, ruthenium, and polinium. In 1844, Russian chemist Karl Karlovich Klaus was able to show that Osann's mistake was due to the impurity of the sample, and Klaus was able to isolate the ruthenium metal.