Question: what are the oxidation numbers of transition metals?
Answer: Rules About Transition Metals Free elements (elements that are not combined with other elements) have an oxidation state of zero, e.g., the oxidation state of Cr (chromium) is 0. For ions, the oxidation state is equal to the charge of the ion, e.g., the ion Fe3+ (ferric ion) has an oxidation state of +3.