What is the hybridization of the carbon atoms in benzene, C6H6? a. sp b. sp2 c. sp3 d. sp3d
The Correct Answer and Explanation is:
Correct Answer: b. sp²
In benzene (C₆H₆), all six carbon atoms are sp² hybridized. Benzene is a planar, cyclic molecule with a hexagonal ring structure. Each carbon atom in benzene is bonded to two other carbon atoms and one hydrogen atom, forming a total of three sigma (σ) bonds.
To form these three sigma bonds, each carbon atom uses three sp² hybrid orbitals. The sp² hybridization arises from mixing one s orbital and two p orbitals from the carbon atom, which results in three equivalent sp² hybrid orbitals arranged in a trigonal planar geometry with 120° bond angles. These hybrid orbitals form sigma bonds with adjacent carbon atoms and hydrogen atoms.
The remaining unhybridized p orbital on each carbon atom lies perpendicular to the plane of the ring. These unhybridized p orbitals overlap sideways with adjacent p orbitals, forming a continuous system of pi (π) bonds above and below the plane of the ring. This delocalization of π electrons across all six carbon atoms creates a resonance structure, which stabilizes the benzene ring and gives it unique chemical properties such as increased stability and uniform bond lengths between carbon atoms.
All carbon-carbon bonds in benzene are of equal length (~1.39 Å), which is intermediate between a single bond and a double bond. This uniformity is a direct result of the delocalized π electron cloud and the sp² hybridization of the carbon atoms.
In summary, each carbon atom in benzene:
- Forms three sigma bonds (two with carbon, one with hydrogen)
- Has one unhybridized p orbital for π bonding
- Is sp² hybridized
This hybridization explains benzene’s planar structure, delocalized electrons, and high stability, characteristics that are central to aromatic chemistry.
