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    Praseodymium

    IsotopeAtomic mass (Da)Isotopic abundance (amount fraction)
    141Pr 140.907 66(2)1

    Praseodymium is a monoisotopic element and its atomic weight is determined solely by its isotope 141Pr. The Commission last revised the standard atomic weight of praseodymium in 2013 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

    CIAAW

    Praseodymium
    Ar(Pr) = 140.907 66(2) since 2013

    The name derives from the Greek prasios for "green" and didymos for "twin" because of the pale green salts it forms. Praseodymium was discovered by the Austrian chemist Carl Auer (Baron von Welsbach) in 1885, who separated it and the element neodymium from a didymium sample (didymium had previously been thought to be a separate element).