As the second part of the energy-level diagram shows, the "real" benzene molecule is 40 kcal mole^-1 more stable than the Kekul� bond model would predict.

We saw the reason in terms of bonding in Chapter 9: In the benzene molecule, six electrons are delocalized around the ring (see diagram), and all six C-C bonds are the same length, intermediate between that of a single and double bond. Each bond has a partial double bond character, and the molecule as a whole gains 40 kcal mole^-1 of added stability.