Benzene, with the chemical formula $$C_6H_6$$, is an aromatic hydrocarbon consisting of six carbon atoms arranged in a hexagonal ring, with alternating single and double bonds. Each carbon atom also bonds with one hydrogen atom.

The structure includes three double bonds and three single bonds interconnecting the carbon atoms in the ring. Here's how these bonds are categorized:

Sigma Bonds ($$\sigma$$-bonds): Sigma bonds are the strongest type of covalent chemical bond. They are formed by head-on overlapping between atomic orbitals. In benzene:

Each of the six carbon atoms forms a sigma bond with one hydrogen atom, giving us total six C-H sigma bonds.
Each carbon-carbon (C-C) single bond in the ring is also a sigma bond. Since there are three C-C single bonds, this adds another three sigma bonds.
For double bonds, each contains one sigma and one pi bond. However, only the sigma component is counted here. Therefore, the three double bonds contribute another three sigma bonds from their C-C interactions.

Total Sigma Bonds: $$6 \,(\text{C-H}) + 3 \,(\text{C-C single bonds}) + 3 \,(\text{C-C part of double bonds}) = 12 \,\sigma\text{-bonds}$$.

Pi Bonds ($$\pi$$-bonds): Pi bonds are formed by the side-to-side overlap of atomic orbitals and are generally weaker than sigma bonds. In benzene, the pi bonds are part of the double bonds. Each double bond contributes one pi bond. Thus:

There are three double bonds in benzene, contributing one pi bond each.

Total Pi Bonds: $$3 \,\pi\text{-bonds}$$.

Therefore, a benzene molecule contains 12 sigma bonds and 3 pi bonds.

JEE Advanced Subjects