chemistry, Science that deals with the properties, composition, and structure of substances (elements and compounds), the reactions and transformations they undergo, and the energy released or absorbed during those processes. Often called the “central science,” chemistry is concerned with atoms as building blocks (rather than with the subatomic domain; see nuclear physics, quantum mechanics), with everything in the material world, and with all living things. Branches of chemistry include inorganic (see inorganic compound), organic (see organic compound), physical, and analytical (see analysis) chemistry; biochemistry; electrochemistry; and geochemistry. Chemical engineering (applied chemistry) uses the theoretical and experimental information obtained in chemistry to build chemical plants and make useful products.
