Which factor primarily determines the shape of a molecule according to the VSEPR theory?

• A. The number of protons in the molecule
• B. The arrangement of electron pairs around the central atom
• C. The color of the atoms involved
• D. The atomic mass of the central atom

Answer: (B)

Verified step by step guidance

1. Understand that VSEPR (Valence Shell Electron Pair Repulsion) theory is used to predict the shape of a molecule based on the repulsions between electron pairs in the valence shell of the central atom.
2. Recognize that the number of protons, atomic mass, or color of atoms do not influence molecular shape directly in VSEPR theory; these factors are unrelated to electron pair repulsions.
3. Focus on the arrangement of electron pairs (both bonding and lone pairs) around the central atom, as these electron pairs repel each other and try to stay as far apart as possible to minimize repulsion.
4. Use the electron pair geometry determined by the number of electron pairs to predict the molecular shape, considering how lone pairs can alter the idealized geometry by exerting stronger repulsive forces.
5. Conclude that the primary factor determining molecular shape in VSEPR theory is the spatial arrangement of electron pairs around the central atom.