Organic chemical compound in which some of the bonding electrons are delocalized (shared among several atoms within the molecule and not localized in the vicinity of the atoms involved in bonding). The commonest aromatic compounds have ring structures, the atoms comprising the ring being either all carbon or mostly carbon with one or more different atoms (usually nitrogen, sulphur, or oxygen). Typical examples are benzene (C
6H
6) and pyridine (C
6H
5N).
© RM 2010. Helicon Publishing is division of RM.