Molecular Shape and Polarity

Objective: Explain the concepts and assumptions used in molecular shape and polarity.

VSEPR predicts approximate geometry by minimizing repulsions among electron domains around a central atom. A single, double, or triple bond counts as one domain; a lone pair also counts as one. Electron-domain geometry includes lone pairs, while molecular shape describes atom positions. Lone pairs can reduce bond angles relative to ideal values. Molecular polarity is the vector sum of bond dipoles and depends on both bond polarity and geometry. The exercises use specified domain counts; exceptions and delocalized bonding require richer models.

Objective: Apply molecular shape and polarity to calculations, evidence, and specified situations.

For the application problems, define the system and list the quantities supplied before choosing a relation. Use domain count = bonding domains + lone-pair domains. The relation must match the stated conditions. Convert to compatible units before substitution, preserve intermediate precision, and report the requested quantity with its unit or sign. When comparing alternatives, check the defining condition rather than a superficial word match. The worked examples below show the setup and calculation separately.