Which term describes compounds with the same formula and connectivity but different spatial arrangement?

• A. Constitutional isomers
• B. Diastereomers
• C. Enantiomers
• D. Stereoisomers

Answer: (D)

Stereochemistry describes compounds that have the same formula and the same connections between atoms but differ in how those atoms are arranged in space. When two molecules share the same constitution yet differ in spatial orientation, they are called stereoisomers. This broad category includes enantiomers, which are non-superimposable mirror images, and diastereomers, which are stereoisomers that are not mirror images. The description given fits the general idea of stereoisomers, not just a subset. Constitutional isomers have different connectivity, so they don’t fit, and diastereomers or enantiomers are specific types within the broader term.