reaction definition chemistry
Decomposition Reaction Defined. A chemical reaction is a process by which the atoms of one or more substances are rearranged to form different substances. There are many types of chemical reactions. These reactions are often classified by what they form or what happens during the course of the reaction. A decomposition reaction is a type of chemical reaction in which a single compound breaks down into two or more elements or new compounds. These reactions often involve an energy source such as heat, light, or electricity that breaks apart the bonds of compounds.