Substance whose molecule s contain one or more (often many more) carbon atom s (excluding carbonates, cyanides, carbides, and a few others; see inorganic compound ).
Until 1828 (see urea ), scientists believed that organic compounds could be formed only by life processes (hence the name). Since carbon has a far greater tendency to form molecular chains and rings than do other elements, its compound s are vastly more numerous (many millions have been described) than all others known. Living organisms consist mostly of water and organic compounds: protein s, carbohydrate s, fat s, nucleic acid s, hormone s, vitamin s, and a host of others. Natural and synthetic fibres and most fuels, drugs, and plastics are organic. functional group s include carboxylic acid s, alcohol s, aldehyde s, ketone s, phenol s, ether s, ester s, and other, more complex, molecules, including heterocyclic compound s, isoprenoid s, and amino acid s.