How to Tell the Charge of Transition Metals

Use the roman numeral first

Iron(III) means Fe3+. Copper(II) means Cu2+. The roman numeral is the metal charge.

Use the anion when no roman numeral is shown

In FeCl3, each chloride is -1, so three chlorides total -3. Iron must be +3.

Check common exceptions

Zinc is usually +2 and silver is usually +1 in introductory formulas.