What is produced at the end of a chemical reaction?

At the end of a chemical reaction, new substances are formed as a result of the rearrangement of atoms and the breaking and forming of chemical bonds. This transformation involves reactants that undergo a chemical change, leading to the creation of products which have different properties from the original substances. The process often includes changes in energy, which may be released or absorbed, but the primary focus is on the generation of new substances that have different chemical identities than what was present before the reaction occurred.

Energy can certainly play a role in chemical reactions, as some reactions are exothermic (releasing energy) or endothermic (absorbing energy), and reactions can also produce various forms of energy, such as heat or light, but these are secondary to the production of new chemical entities. Therefore, the essence of a chemical reaction is the formation of new substances, distinguishing it from merely producing heat or light.