In a chemical equation, what are the substances written on the left of the arrow called?

1. A chemical equation describes a reaction using symbols for the elements involved. 2. Compounds on the left of the arrow are called the reactants and are needed for the reaction to take place. 3. The compounds on the right are the products, which is what the reaction forms. _Source: Siyavula Physical Sciences Grade 10 (Everything Science, CC BY 4.0), Chapter 14: Representing chemical change_