What is the term used for the substances involved in a chemical reaction?

The term for the substances involved in a chemical reaction is "reactants." Reactants are the starting materials that undergo a chemical change during the reaction process. They are transformed into products as a result of the reaction. Understanding this concept is fundamental in chemistry, as it helps to clarify how substances interact and change their chemical structure.

While products refer to the resulting substances after the reaction has taken place, reagents are typically used in a way that indicates they are the chemicals introduced to facilitate the reaction. Compounds represent a broader category of substances formed when two or more elements chemically bond together, and while they can serve as reactants, not all reactants are compounds. Thus, the clearest definition for substances that participate in the starting phase of a chemical reaction is reactants.