According to Valence Shell Electron Pair Repulsion (VSEPR) Theory, why do lone (nonbonding) pairs of electrons on a central atom affect the molecular shape?

• A. Lone pairs attract bonding pairs, pulling them closer together and increasing bond angles.
• B. Lone pairs are always located opposite to bonding pairs, resulting in a linear geometry.
• C. Lone pairs occupy more space than bonding pairs, causing greater repulsion and altering bond angles.
• D. Lone pairs do not interact with bonding pairs and therefore have no effect on molecular shape.

Answer: (C)

Verified step by step guidance

1. Understand that according to VSEPR theory, electron pairs around a central atom repel each other and arrange themselves to minimize repulsion, which determines the molecular shape.
2. Recognize that there are two types of electron pairs: bonding pairs (shared between atoms) and lone pairs (nonbonding pairs localized on the central atom).
3. Note that lone pairs occupy more space than bonding pairs because lone pairs are localized closer to the nucleus and are not shared between atoms, leading to stronger repulsive forces.
4. Because lone pairs repel more strongly, they push bonding pairs closer together, which changes the bond angles and thus alters the molecular geometry.
5. Conclude that the presence of lone pairs affects molecular shape by increasing repulsion and modifying bond angles, which is why lone pairs must be considered when predicting molecular geometry using VSEPR theory.