A salt is an ionic compound containing some cation other than hydrogen and some anion other than hydroxide and oxide. Since the compound must be electrically neutral, the total positive valence (from all of the cations) must equal the total negative valence (from all the anions). This gives us a method for determining the valence of any particular ion in the formula. The names for salts are made by writing the name of the cation followed by the name of the anion. For example, CaCl2 has calcium as the cation and chloride as the anion, so the compound is called calcium chloride. FeSO4 has sulfate as the anion, but we need to know whether the ion is ferrous ion or ferric ion. This is easy for us to do: since we know the total negative valence (from sulfate) is -2, the total positive valence (for iron) must be +2; therefore, it is ferrous ion. The compound is ferrous sulfate.