A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together in a defined spatial arrangement by chemical bonds. Chemical compounds can be molecular compounds held together by covalent bonds, salts held together by ionic bonds, intermetallic compounds held together by metallic bonds, or complexes held together by coordinate covalent bonds. Pure chemical elements are not considered chemical compounds, even if they consist of molecules which contain only multiple atoms of a single element (such as H₂, S₈, etc.), which are called diatomic molecules or polyatomic molecules.

There are exceptions to the definition above, and large amounts of the solid chemical matter familiar on Earth do not have simple formulas. Certain crystalline compounds are called "non-stoichiometric" because they vary in composition due to either the presence of foreign elements trapped within the crystal structure or a deficit or excess of the constituent elements. Such non-stoichiometric chemical compounds form most of the crust and mantle of the Earth.

The Chemical Brothers are a British electronic music duo composed of Tom Rowlands and Ed Simons. Originating in Manchester in 1991, along with The Prodigy, Fatboy Slim, The Crystal Method, and fellow acts, they were pioneers at bringing the big beat genre to the forefront of pop culture.

Ed Simons was born in Herne Hill, South London on 9 June 1970 to a barrister mother and a father who was not around much when Simons was growing up. Simons' two main interests when he was young were aeroplanes and musicals. Simons attended two South London public schools, Alleyn's School and Dulwich College. During his school years, he developed a fondness for rare groove and Hip hop music, having frequented a club called The Mud Club from the age of 14. By the time he left school, his two main musical interests were two Manchester bands, New Order and The Smiths. After finishing school with 11 O levels and three A-levels, he continued on to study history, especially late medieval history, at the University of Manchester.^{[citation needed]}