Answer
Fe$_{2}$O$_{3}$
Work Step by Step
The iron ion has a net 3+ charge and the oxygen ion has a net 2- charge. If you have 2 iron atoms, the positive charge becomes 6+, if you have 3 oxygen atoms, the negative charge becomes 6-. You can see that the two charges balance out to a net charge of 0. This means that the chemical formula is Fe$_{2}$O$_{3}$.
