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    IsotopeAtomic mass (Da)Isotopic abundance (amount fraction)
    69Ga 68.925 574(8)0.601 08(50)
    71Ga 70.924 703(6)0.398 92(50)

    In 1961, the Commission recommended Ar(Ga) = 69.72, based on the chemical ratio determinations as well as the isotope-abundance determinations. Recalculating the chemical ratios based on current values of the other atomic weights involved yields Ar(Ga) = 69.735, while the mass-spectrometric value with current atomic masses gives Ar(Ga) = 69.72. Furthermore, highly precise coulometric assay of Ga and As yielded Ar(Ga) = 69.737. Meanwhile, new mass-spectrometric measurements confirmed the earlier mass-spectrometric values, yielding Ar(Ga) = 69.724(2). Facing with this dataset, the Commission recommended an atomic weight of Ar(Ga) = 69.723(4) in 1983 favouring the mass-spectrometric data.

    Significant variations occur in the n(69Ga)/n(71Ga) ratio of commercially high-purity Ga from different lots of material and different manufacturers, some exhibiting ratios 0.19 % higher and 0.12 % lower than the laboratory reference material. Based on this information, in 1987 the Commission recommended Ar = 69.723(1), which has remained unchanged since that time.

    Purification of Ga by successive recrystallizations is accompanied by small variations in isotopic composition, which measurably affect the triple-point temperature of gallium.

    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(Ga) = 69.723(1) since 1987

    The name derives from the Latin gallia for France. It was discovered in zinc blende by the French chemist Paul-Emile Lecoq de Boisbaudran in 1875. It was first isolated in 1878 by Lecoq de Boisbaudran and the French chemist Émile-Clément Jungflesch.

    Isotopic reference materials of gallium.