In the VSEPR theory, what is the primary factor that determines the shape of a molecule?

• A. The repulsion between electron pairs in the valence shell of the central atom
• B. The number of protons in the nucleus
• C. The mass of the atoms involved
• D. The atomic number of the central atom

Answer: (A)

Verified step by step guidance

1. Understand that VSEPR (Valence Shell Electron Pair Repulsion) theory is used to predict the shape of molecules based on the idea that electron pairs around a central atom repel each other.
2. Recognize that the shape of a molecule is primarily determined by the repulsions between electron pairs (both bonding and lone pairs) in the valence shell of the central atom, as these repulsions cause the electron pairs to arrange themselves as far apart as possible.
3. Note that factors such as the number of protons in the nucleus, the mass of the atoms, or the atomic number of the central atom do not directly influence the molecular shape in VSEPR theory.
4. Conclude that the key factor in determining molecular geometry is the spatial arrangement that minimizes repulsion between electron pairs around the central atom.
5. Therefore, the correct answer is that the shape of a molecule is determined by the repulsion between electron pairs in the valence shell of the central atom.