Organic Chemistry MCAT Practice Exam 2025 - Free MCAT Practice Questions and Study Guide

Conformational isomers, also known as conformers, are defined as molecules that have the same connectivity of atoms but differ in the spatial orientation of these atoms due to rotation around single (sigma) bonds. This rotational freedom allows for various arrangements, or conformations, of the molecule without breaking any bonds. For example, in alkanes, the rotation about carbon-carbon single bonds leads to different spatial arrangements that can impact physical properties, such as boiling points and steric interactions.

In contrast, the other definitions provided do not accurately describe conformational isomers. While functional groups are crucial in distinguishing different types of isomers, they do not relate to conformational isomers as both types contain identical functional groups. Furthermore, the term "different connectivity" implies structural isomers rather than conformers, which maintain the same atom-to-atom connections. Lastly, molecular weight considerations do not directly apply to the spatial arrangements of atoms related to conformational isomers as they share identical molecular formulas.