I know aluminum has 3 valence electrons and oxygen has 7, but if anyone could explain the chemical formula to me it would be great.
You are right about aluminum having 3 valence electrons, but oxygen has 6. Oxygen wants two more to get to 8. So the ions are Al +3 and O-2. The formula is Al2O3
The chemical formula of aluminium oxide is Al2O3 An aluminium ion has a 3+ charge, because it loses 3 electrons when it reacts. An oxygen ion has a 2- charge, because it gains 2 electrons when it reacts. In aluminium oxide, the charges of the ions need to cancel out. So... 2 aluminium ions -- 6+ total charge , 3 oxygen ions -- 6- total charge The charges cancel out.
