Benzene has the chemical formula C6H6 where each Carbon atom is bonded to two other Carbon atoms and a single Hydrogen atom. The 4th bond pair of electrons from each Carbon atom is delocalised, creating a delocalised cloud of electrons above and below the plane. Benzene is an hexagonal ring in shape with bond angles of 120degrees between Carbon atoms.All the bond lengths in Benzene are equal. Because of the system of delocalised electrons Benzene is also far more energetically stable than it should be, its extra stability is know as its delocalisation energy.Because of its increased stability Benzene will not readily unergo addition reactions, instead it undergoes addition reactions whereby a Hydrogen atom is replaced by another atom or group (e.g. Chlorine in the chlorination of Benzene).