Delocalized pi lobes

This interpretation leads to the conclusion that six bonding electrons move freely around the double ring structure formed by the overlapping delocalized pi lobes. Because of this, the benzene structure is often represented by the symbol ... 

The sp orbital (known as a digonal orbital) is a merger of an s and a p orbital which consists of two lobes, one large and one small, as illustrated in Fig. 2.18. An sp bond consists of two sp orbitais which, because of mutual repulsion, form an angle of 180° and, consequently, the sp molecule is linear. The bond, like all overlap bonds, is a sigma (a) bond and has high strength. The sp orbitals account fortwo of the electrons of the carbon atom. The other two valence electrons are free, delocalized pi n) orbited electrons which are available to form subsidiary pi (n) bonds in a manner similar to the sp hybridization. 

The sigma bond framework (in green) forms by the overlap of sp hybrid orbitals on each carbon atom H atom Is orbitals overlap these hybrid orbitals to form C—H bonds. Delocalized pi orbitals form by the overlap of carbon atom 2p orbitals that are perpendicular to the plane of the molecule they give orbitals with lobes above and below this plane. Only the lowest-energy pi orbital is shown (yellow). 

---