Question

What is the charge of iron in the iron oxide compound, `Fe_2O_3`?

Answer 1

`3+`

Explanation:

Iron(III) oxide is a neutral compound, which implies the net charge of the compound equals `0`; i.e. the charges of all the atoms must add up to `0`. Oxygen in nearly all cases has a charge of `2-` (except for a few compounds such as potassium superoxide, `KO_2`), so the total ionic charge the `O` atoms exhibit is `3(-2) = -6`. If two `Fe` atoms equalize this charge and make it neutral, the charge (oxidation state) of `Fe` in this compound must be `3+`.