A chemical reaction is the process in which atoms present in the starting substances rearrange to give new chemical combinations present in the substances formed by the reaction. These starting substances of a chemical reaction are called the reactants, and the new substances that result are called the products.
The chemical formula for magnesium sulfate is MgSO4, so it shows that there are four atoms of oxygen but not sulfur. There is only one atom of sulfur in the formula
