Structure of Benzene:
Benzene is an aromatic compound with cyclic planar structure. The molecular formula of benzene is C6H6.The structure of benzene consists of hexagonal planar ring of six carbon atoms with delocalized clouds of evenly distributed pi-electrons. Each carbon atom is Sp2 hybridized and the bond angle is 120 degree and has bond length of 1.29 Armstrong. The first acceptable structure of benzene was proposed by Kukule which is shown as below.
Kukule proposed that in benzene, 6 carbons are bonded together to form hexagonal planar ring with alternate double bond. Each carbon atom is bonded to one hydrogen as well. To overcome this criticism of this structure, Kukule later proposed that benzene actually doesn’t exist in the form of A and B. The double bond continuously interchanges its position and benzene actually is the average of structures A and B which we now called as resonance.
Here, A and B are the two the canonical forms and C is called the resonance hybrid.
Resonance: If a single molecule can be represented by two or more structures, then a common structure that resembles those multi structures is made to represent that molecule. This phenomenon is called resonance. In other way, resonance is the representation of structure of a molecule or an ion by two or more conventional formula. It is a key component of the valance bond theory. In case of benzene, two different structures with alternate double bond, interchanging its position are represented by a dotted ring bonding of benzene as shown above.
The figure below shows the wide representation of the structure of benzene.