Chemistry deals with the properties of matter, and the transformation and interactions of matter and energy. Central to chemistry is the interaction of one substance with another, such as in a chemical reaction, where a substance or substances are transformed into another. Chemistry primarily studies atoms and collections of atoms such as molecules, crystals or metals that make up ordinary matter. According to modern chemistry it is the structure of matter at the atomic scale that determines the nature of a material.
Chemistry has many specialized areas that overlap with other sciences, such as physics, biology or geology. Scientists who study chemistry are called chemists. Historically, the science of chemistry is a recent development but has its roots in alchemy which has been practiced for millennia throughout the world. The word chemistry is directly derived from the word alchemy.