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Example 2.13: Naming Ionic Compounds

Name the following ionic compounds, which contain a metal that can have more than one ionic charge:
(a) \(\ce{Fe2S3}\)
(b) \(\ce{CuSe}\)
(c) \(\ce{GaN}\)
(d) \(\ce{CrCl3}\)
(e) \(\ce{Ti2(SO4)3}\)

Solution

The anions in these compounds have a fixed negative charge ( \(\ce{S^2-}\), \(\ce{Se^2-}\) , \(\ce{N^3-}\), \(\ce{Cl^-}\), and \(\ce{SO4^2-}\)), and the compounds must be neutral. Because the total number of positive charges in each compound must equal the total number of negative charges, the positive ions must be \(\ce{Fe^3+}\), \(\ce{Cu^2+}\), \(\ce{Ga^3+}\), \(\ce{Cr^3+}\), and \(\ce{Ti^3+}\). These charges are used in the names of the metal ions: (a) iron(III) sulfide
(b) copper(II) selenide
(c) gallium(III) nitride
(d) chromium(III) chloride
(e) titanium(III) sulfate