Arenes and benzene
In this topic, aromatic compounds, or arenes, are organic compounds containing one or more benzene rings with a delocalised π electron system. The chemical use of aromatic describes this type of bonding rather than the smell of a substance.
Benzene has the molecular formula . Its ring contains six carbon atoms, and each of those carbon atoms is also attached to one hydrogen atom.
Adjacent p orbitals form a continuous conjugated π system. Consequently, the π electron density extends around all six carbon atoms instead of being restricted to three separate C=C bonds.
A localised comparison model
Kekulé's localised representation assigns alternating bond orders around the six-membered carbon ring: three edges are drawn as C–C single bonds and the other three as C=C double bonds. Experimental evidence shows that these alternating bond types are not fixed in actual benzene.