AB , is an interhalogen T-shaped molecule. The number of lone pairs of electrons on A is ________. ( — Chemical Bonding Chemistry Question

💡 Solution & Explanation

**Step 1: Identify the interhalogen compound AB₃** Since AB₃ is T-shaped, A must be the central atom and B represents three halogen atoms (likely fluorine or chlorine). **Step 2: Determine A's identity** A T-shaped geometry with 3 bonding pairs indicates the central atom has 5 electron domains total. This is characteristic of a halogen in the +3 oxidation state. A is likely Br or I (from Group 17). **Step 3: Apply VSEPR theory** - For a T-shaped molecule: 3 bonding pairs + 2 lone pairs = 5 electron domains - The molecular geometry is T-shaped when 2 lone pairs occupy axial positions **Step 4: Calculate using electron domain formula** For central atom A (e.g., Br in BrF₃): - Valence electrons on A = 7 (halogen) - Electrons used in 3 bonds = 3 × 2 = 6 electrons - Remaining electrons = 7 - 6 = 1 pair = **2 electrons** **Step 5: Verify lone pair count** With 5 total electron domains and 3 bonding pairs: - Lone pairs = 5 - 3 = **2 lone pairs** Therefore, the answer is **2.00**.