How many sigma bonds are present in toluene?

Toluene is an aromatic hydrocarbon with the chemical formula \( C_6H_5CH_3 \). It consists of a benzene ring (a six-carbon ring with alternating double bonds) and a methyl group (\(-CH_3\)) attached to it.

To determine the number of sigma bonds in toluene, let’s break down its structure:

1. **Benzene Ring:**
- The benzene ring is a planar ring with six carbon atoms, where each carbon is bonded to two other carbons (in the ring) and one hydrogen atom.
- Each carbon-carbon bond in the benzene ring is a sigma bond. There are six carbon-carbon sigma bonds in the ring.
- Each carbon-hydrogen bond is also a sigma bond. There are six hydrogen atoms, so there are six carbon-hydrogen sigma bonds.

2. **Methyl Group (\(-CH_3\)):**
- The methyl group is attached to one of the carbons in the benzene ring. It has three carbon-hydrogen sigma bonds.
- The carbon in the methyl group is bonded to the benzene ring through a single bond. This is a sigma bond between the carbon of the methyl group and the carbon of the benzene ring.

Now, let’s count the sigma bonds:

- **In the benzene ring:**
- Carbon-carbon sigma bonds: 6
- Carbon-hydrogen sigma bonds: 6

- **In the methyl group:**
- Carbon-hydrogen sigma bonds: 3
- Carbon-benzene ring sigma bond: 1

Adding these together:

\[ 6 \text{ (C-C in benzene)} + 6 \text{ (C-H in benzene)} + 3 \text{ (C-H in methyl group)} + 1 \text{ (C-C between methyl group and benzene)} = 16 \text{ sigma bonds} \]

So, toluene has a total of **16 sigma bonds**.