reactant

In chemistry, a reactant is a substance that is altered during a chemical reaction. A chemical reaction is a process where one or more reactants are transformed into one or more different substances, known as products. This transformation involves rearranging the atoms of the reactants to form new substances with different properties. Chemical reactions are fundamental to many aspects of life and technology, from burning fuels to biological processes within living organisms. They are distinct from physical changes, where a substance's chemical identity remains the same despite alterations in its physical state.