Resonance Structures of Benzene:
- Kekulé Structures:
- Benzene has six carbon atoms in a ring, each bonded to one hydrogen.
- There are two main resonance forms (Kekulé structures) that differ only in the positions of the double bonds:
- In one structure, double bonds are between C1–C2, C3–C4, and C5–C6.
- In the other structure, double bonds are between C2–C3, C4–C5, and C6–C1.
- The single and double bonds “alternate” around the ring in these structures.
- Resonance Hybrid:
- The true structure of benzene is not exactly either Kekulé structure.
- All six carbon–carbon bonds are equivalent with bond lengths intermediate between a single and double bond.
- The electrons in the π-bonds are delocalized over the entire ring, giving benzene extra stability (aromaticity).
Summary: Benzene has two resonance forms (Kekulé structures), and its actual structure is a resonance hybrid with delocalized electrons and equal bond lengths.