Bromine water stays orange. Alkenes decolorize it instantly. Benzene just shrugs it off.
The textbook sketch shows three double bonds alternating around a six-carbon ring.
But X-ray data says every bond is identical, 139 picometers, between single and double.
Each carbon's p orbital overlaps its neighbors, so six pi electrons delocalize around the ring.
Delocalization lowers its energy by about 152 kilojoules per mole. That aromatic stability resists addition reactions.