Question

The correct order of covalent bond character of \( BCl_3, CCl_4, BeCl_2, LiCl \) is:

• A. \( LiCl < BeCl_2 < BCl_3 < CCl_4 \)
• B. \( CCl_4 < BeCl_2 < BCl_3 < LiCl \)
• C. \( CCl_4 < BCl_3 < BeCl_2 < LiCl \)
• D. \( LiCl < BCl_3 < BeCl_2 < CCl_4 \)

Hint:

Smaller cations and larger anions increase covalent character due to higher polarization.

Answer 1

The Correct Option is A

Step 1: Apply Fajan’s Rule Covalent character increases with: - Higher cation charge density. - Larger anion size. Step 2: Arrange Based on Covalent Character \[ LiCl < BeCl_2 < BCl_3 < CCl_4 \]

Answer 2

The covalent character of ionic compounds depends on the polarizing power of the cation and the polarizability of the anion, as described by Fajans' rules. Let's analyze each compound:

1. \( LiCl \):
- Lithium ion (Li⁺) is a small cation with relatively high charge density.
- However, chloride ion (Cl⁻) is a large anion with moderate polarizability.
- Lithium chloride has significant ionic character but less covalent compared to others in this list.

2. \( BeCl_2 \):
- Beryllium ion (Be²⁺) is very small and highly charged, giving it a strong polarizing power.
- This causes significant distortion of the electron cloud of Cl⁻, increasing covalent character.

3. \( BCl_3 \):
- Boron is a non-metal and forms covalent bonds.
- \( BCl_3 \) is a covalent molecule with trigonal planar geometry.
- It exhibits more covalent character than \( BeCl_2 \).

4. \( CCl_4 \):
- Carbon is a non-metal, and \( CCl_4 \) is a purely covalent molecule with tetrahedral geometry.
- It has the highest covalent character among the given compounds.

Summary of covalent character order:
LiCl < BeCl_2 < BCl_3 < CCl_4

This order indicates that lithium chloride is the most ionic, while carbon tetrachloride is the most covalent.

Therefore, the correct order of covalent bond character is:
LiCl < BeCl_2 < BCl_3 < CCl_4