* Identify the subscript for oxygen: In the chemical formula Al₂O₃, the subscript for oxygen is 3. This means there are 3 oxygen atoms in each molecule of aluminum oxide (Al₂O₃).
* Multiply by the coefficient: The coefficient in front of the formula is 3. This means we have 3 molecules of Al₂O₃.
* Calculate the total: To find the total number of oxygen atoms, multiply the subscript by the coefficient: 3 oxygen atoms/molecule * 3 molecules = 9 oxygen atoms
Therefore, there are 9 oxygen atoms in 3Al₂O₃.
