Describe the structure of benzene with reference to delocalisation and an analysis of the Kekule structure.

Benzene is a circular molecule composed of 6 carbon atoms, each forming a single bond to two other carbons and one hydrogen. The fourth electron in the valence shell of each carbon is placed in a p orbital that is perpendicular to the plane of the ring. These p orbitals overlap to form a delocalised pi system around the ring of the molecule. This projects electron density above and below the ring. This pi system means that there are no formal 2-centre-2-electron pi bonds in benzene. However, the Kekule structure, which does show formal 2c-2e pi bonds is often used as the easiest representation of benzene.