Reactants
Summary: Starting substances in a chemical reaction that are transformed into products. Tags: concepts chemistry Created: 2026-05-03T00:00:00Z Last Updated: 2026-05-03T00:00:00Z
Content
Reactants are the starting substances present before a chemical reaction takes place. During a reaction, bonds between atoms in reactants break and rearrange to form new substances called products.
In a word equation, reactants appear on the left side of the arrow:
Reactant A + Reactant B → Product
Example: In magnesium + oxygen → magnesium oxide, magnesium and oxygen are the reactants.