Benzene, C6H6, is known experimentally to possess six identical C–C bond lengths of approximately 1.39 Å, a value intermediate between typical single and double carbon–carbon bonds.
(a) Draw the two most commonly cited resonance (Kekulé) structures of benzene. Include all C–C and C–H bonds but omit lone pairs for clarity.
(b) Using only the structures from part (a), determine the average bond order for any C–C bond in the aromatic ring. Show your reasoning.
(c) Explain why every C–C bond in benzene has the same length, despite the presence of distinct single and double bonds in each individual structure.
(d) Discuss how the delocalization reflected in your answer to part (b) contributes to the thermodynamic stability (resonance energy) of benzene relative to a hypothetical cyclohexatriene containing three isolated C=C bonds.