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Chemistry is a subcategory of physical science that studies the composition, structure, properties and change of matter. Chemistry is primarily concerned with atoms and molecules and their interactions and transformations. An example would be the properties of the chemical bonds formed between atoms to create chemical compounds.

Chemistry studies the involvement of electrons and various forms of energy in photochemical reactions, oxidation-reduction reactions, changes in phases of matter, and separation of mixtures. Specialized fields of chemistry include pharmaceutical agents and the preparation and properties of complex substances, such as alloys, polymers, biological molecules.

Chemistry is sometimes called the central science because it bridges other natural sciences like physics, geology and biology. Chemistry is a subcategory of physical science but is distinct from physics.

The etymology of the word chemistry has been much disputed. The history of chemistry can be traced to certain practices, known as alchemy, which had been practiced for several millennia in various parts of the world. The word chemistry comes from the word alchemy, an earlier set of practices that encompassed elements of chemistry, metallurgy, philosophy, astrology, astronomy, mysticism and medicine. Alchemy is commonly thought of as the quest to turn lead or another common material into gold.