Final answer:
In a chemical equation, the substances listed on the left side are the reactants, while the substances on the right side are the products.
Step-by-step explanation:
The substances to the left of the arrow in a chemical equation are called reactants. Reactants are the substances present at the start of a chemical reaction. On the other hand, the substances to the right of the arrow are called products. Products are the substances present at the end of a chemical reaction.