Energy can neither be created nor destroyed, but it is always in the process of transforming from one form to another. Readers will explore the concepts behind chemical energy and the transformation of energy into different forms. They will learn how batteries work, why fossil fuels are a source of stored energy, and how the forming and breaking of bonds relates to the release of energy. Sidebars profile scientists who have made important discoveries about energy and photographs illustrate chemical energy in the world around us.