Question

The number of σ bonds, π bonds and having pair of electrons in pyridine respectively.

• A. 12, 3, 0
• B. 11, 3, 1
• C. 12, 2, 1
• D. 11, 2, 0

Answer 1

The Correct Option is B

To solve the question about the structure of pyridine, we need to determine the number of sigma (\(\sigma\)) bonds, pi (\(\pi\)) bonds, and lone pairs of electrons in the pyridine molecule.

Step 1: Understanding Pyridine Structure

Pyridine is a six-membered heterocyclic aromatic compound with the chemical formula \( \text{C}_5\text{H}_5\text{N} \). It consists of a nitrogen atom replacing one of the CH groups in benzene. This creates a ring with alternating single and double bonds.

Step 2: Counting Bonds

1. Sigma (\(\sigma\)) Bonds: Each atom in the ring forms \(\sigma\) bonds with its neighboring atoms. In pyridine:
   • The ring consists of 5 carbon atoms and 1 nitrogen atom.
   • Each of the 6 atoms forms \(\sigma\) bonds with its two neighboring atoms. This accounts for \(6 \times 2 = 12\) \(\sigma\) bonds.
   • However, one \(\sigma\) bond overlaps each neighboring pair of atoms. Thus, the number of distinct \(\sigma\) bonds within the ring is 6.
   • Additionally, each carbon and the nitrogen atom forms a \(\sigma\) bond with hydrogen, contributing 5 more \(\sigma\) bonds.
   • Hence, total \(\sigma\) bonds = 6 (ring) + 5 (C-H or N-H) = 11.
2. Pi (\(\pi\)) Bonds: In the pyridine ring, every alternate carbon-carbon bond is a double bond, which contributes one \(\pi\) bond. Therefore, there are 3 \(\pi\) bonds.

Step 3: Lone Pair of Electrons

The nitrogen atom in pyridine possesses one lone pair of electrons in its electronic configuration.

Conclusion:

The correct breakdown of the number of bonds and lone pairs in pyridine is as follows:

1. \(\sigma\) Bonds: 11
2. \(\pi\) Bonds: 3
3. Lone Pair of Electrons: 1

Therefore, the correct answer is 11, 3, 1.

The given option that matches is: 11, 3, 1.