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6.6: Trends for the Oxides of the Group 13 Elements

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  • All of the Group 13 elements form a trivalent oxide (M2O3). The chemical properties of the oxides follow the trend acidic to basic going down the Group (Table \(\PageIndex{1}\)). The physical properties are consistent with the electronegativities and covalent character in the M-O bonds. Thallium oxide is unique in that it decomposes above 100 °C to yield the thalium(I) oxide, Tl2O. The other oxides are all stable to high temperatures.

    Table \(\PageIndex{1}\): Properties of the Group 13 oxides.
    Oxide Color Chemical property Melting point (°C)
    B2O3 White/colorless Weak acid 450 (trigonal), 510 (tetrahedral)
    Al2O3 White/colorless Amphoteric 2072 (α)
    Ga2O3 White/colorless Amphoteric 1900 (α), 1725 (β)
    In2O3 Yellow Weakly basic 1910
    Tl2O3 Brown-black Basic, oxidizing 100 (decomposes)


    • G. E. Jellison, Jr., L. W. Panek, P. J. Bray, and G. B. Rouse, Jr., J. Chem. Phys., 1977, 66, 802.
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