Chemistry - CHEMICAL BONDING Question with Solution | TestHub

Question Explanation :

Identify molecules where hybridization fails to predict the bond angle.

Concept:

Drago's Rule (No Hybridization), VSEPR.

Solution:

• Drago's Rule: For Period 3/below central atoms (P, S, Sb) with lone pairs and less electronegative

peripheral atoms (H), hybridization is minimal.

• This results in bond angles near 90° (pure p-orbitals) instead of the expected 109.5°(sp³).

• 1. PH₃ ( P is Period 3, lone pair): Bond angle $\approx 93.5^{\circ }$. Fails.

• 2. SbH₃ (Sb is Period 5, lone pair): Bond angle $\approx 91.3^{\circ }$. Fails.

• 3. SiH₄ (Si is Period 3, NO lone pair): Angle 109.5°. Valid.

• 4. H₂S (S is Period 3, two lone pairs): Bond angle $\approx 92.1^{\circ }$. Fails.