Aromatic chemistry
The word aromatic was initially applied to benzene-like structures due to the distinctive aroma of these compounds, but the word now means something dissimilar in modern chemistry. Aromatic compounds go through distinctive reactions that set them apart from other functional groups. They are extremely unsaturated compounds, but not like alkenes and alkynes, they are comparatively unreactive and will tend to go through reactions that include retention of their unsaturation. We have already described the reasons for the stability of benzene. Benzene is a six-membered ring structure along with three formal double bonds. Though, the six π electrons involved are not localized among any two carbon atoms. In place of it, they are delocalized around the ring that results in an increased stability. This is why benzene is frequently written with a circle in the center of the ring to signify the delocalization of the six π electrons.
Figure: Representations of benzene
Reactions that disrupt this delocalization are not favored because it means a loss of stability, so benzene goes through reactions in which the aromatic ring system is retained. All six carbon atoms in benzene are sp2 hybridized, and the molecule itself is cyclic and planar - the planarity being essential if the 2p atomic orbitals on every carbon atom are to overlap and result in delocalization.