products
When a chemical reaction occurs, the atoms in the reactants rearrange their chemical bonds to make products. The new arrangement of bonds does not have the same total energy as the bonds in the reactants. Therefore, when chemical reactions occur, there will always be an accompanying energy change. In some reactions, the energy of the products is lower than the energy of the reactants. Thus, in the course of the reaction, the substances lose energy to the surrounding environment. Such reactions are exothermic and can be represented by an energylevel diagram like the one in http://catalog. flatworldknowledge. com/bookhub/reader/2547 gob-ch07_s04_f01. In most cases, the energy is given off as heat although a few reactions give off energy as light . Figure 7.3 Exothermic Reactions.