Final answer:
Two disubstituted cyclopentane molecules are classified based on their three-dimensional geometry and group attachment. Enantiomers are non-superimposable mirror images, while diastereomers are stereoisomers that are not mirror images but have the same molecular formula with different configurations. Constitutional isomers have the same formula but different connectivity.
Step-by-step explanation:
To classify two disubstituted cyclopentane molecules as the same compound, enantiomers, diastereomers, constitutional isomers, or not isomeric, we need to analyze their three-dimensional geometry and attachment of groups. Enantiomers are non-superimposable mirror images of each other that do not possess any plane of symmetry. The presence of a plane of symmetry in a molecule would make it a meso compound which is achiral. Diastereomers are stereoisomers that are not mirror images; for instance, trans-1,2-dimethylcyclopropane would be considered diastereomers of cis-1,2-dimethylcyclopropane. Constitutional isomers have the same molecular formula but differ in the connectivity of their atoms, while non-isomeric molecules are completely different compounds. Determining the relationship between two molecules involves comparing their structures. If they can be superimposed on one another, they are the same compound. If they are mirror images and non-superimposable, they are enantiomers. If they are not mirror images but have the same molecular formula and are connected differently, they are diastereomers. If they differ in the way their atoms are connected, they are constitutional isomers. And if they do not share the molecular formula, they are not isomeric.