Final answer:
The correct formula for aluminum oxide is Al2O3. This formula ensures that the total positive charge from the aluminum ions balances with the total negative charge from the oxygen ions, resulting in an electrically neutral compound.
Step-by-step explanation:
The correct formula for aluminum oxide is Al2O3. When forming ionic compounds, the charges on the ions must balance out to result in a neutrally charged substance. Aluminum, represented by Al, carries a 3+ charge (Al3+), and oxygen, represented by O, carries a 2- charge (O2-). To ensure electrical neutrality, two aluminum ions will balance out with three oxygen ions, resulting in the formula Al2O3. This is because two Al3+ ions (totaling 6+ charges) will balance with three O2- ions (totaling 6- charges), giving the neutral compound aluminum oxide.