Why does iron oxide have subscripts in the formulas?
The Octet Rule is the basis for the predictions about the charges on ions. A compound is not stable unless the number of electrons which are lost equals those gained. The electrons gained or lost on each atom may be different. The exchange of electrons continues until there are no left over electrons and no empty spots. This sometimes results in several atoms being required. The subscripts are written to show how many of each kind of atom is involved.
