In the structure of $\mathrm{benzene}$, what does the ring in the center of the hexagon represent?

• A. It represents a localized pair of $e{-}^2$ on one $C$ atom.
• B. It represents the delocalized $\pi$ electrons shared equally among all six $C$ atoms.
• C. It represents a lone pair of $e{-}^2$ on a $H$ atom.
• D. It represents a single double bond between two $C$ atoms.

Answer: (B)

Verified step by step guidance

1. Understand that benzene is a planar, cyclic molecule with six carbon atoms arranged in a hexagonal ring.
2. Recognize that each carbon atom in benzene is sp2 hybridized, contributing one unhybridized p orbital perpendicular to the ring plane.
3. These p orbitals overlap sideways to form a continuous ring of electron density above and below the plane of the carbon atoms, creating a system of delocalized π electrons.
4. The circle inside the hexagon in benzene's structure symbolizes this delocalized π electron cloud, indicating that the electrons are shared equally among all six carbon atoms rather than localized between two atoms.
5. This delocalization leads to resonance stabilization, meaning the actual structure is a hybrid of multiple resonance forms with equal bond lengths, rather than alternating single and double bonds.