the structure and behaviour of atoms (elements)
the composition and properties of compounds
the reactions between substances with their accompanying energy exchange
the laws that unite these phenomena into a comprehensive system.
Chemistry is not an isolated discipline, for it merges into physics and biology. The origin of the term is obscure. Chemistry evolved from the medieval practice of alchemy. It's bases were laid by such men as Boyle, Lavoisier, Priestly, Berzelius, Avogadro, Dalton and Pasteur.