Ionic Compounds with Multivalent Elements
Ionic compounds with multivalent elements are almost the same as binary ionic compounds, except that the positive ion has more than one possible charge. These ions include copper, gold, iron, and lead. For example, iron has a +2 or a +3 charge. When naming ionic compounds with these multivalent elements, the name stays the same, except a Roman numeral is added. The Roman numeral represents the charge of that ion, so iron can be iron(II) or iron(III).
For example, you are given the chemical formula FeBr2. Looking at the periodical table of elements, you see that it is iron bromide; however, iron is a multivalent element. To find out which iron ion is used, look at bromine. Bromine has a – charge, and there are two, so that would mean two bromine ions. The chemical formula is then stating that there are two bromine ions for one iron ion. This would mean that the iron ion used here is iron(II). The name of this compound would then be iron(II) bromide.
A quiz to practice naming ionic compounds with multivalent elements: http://mysite.verizon.net/redslime/ChPh/Quiz/compounds/compound2a.htm
Copper, which has two possible charges: +1 and +2