`BCl_(3)` is planar but anhydrous `AlCl_(3)` is tetrahedral . Explain .

Explanation

To explain why BCl₃ is planar while anhydrous AlCl₃ is tetrahedral, we can break down the reasoning into several steps:

### Step 1: Understanding the Elements
Both boron (B) and aluminium (Al) belong to Group 13 of the periodic table. They both have three valence electrons:
- Boron: Atomic number 5, electronic configuration: 1s² 2s² 2p¹ → Valence electrons: 3
- Aluminium: Atomic number 13, electronic configuration: 1s² 2s² 2p⁶ 3s² 3p¹ → Valence electrons: 3

### Step 2: Bonding with Chlorine
...