Semmelweis Chemistry Entrance Exam Practice 2026 - Complete Prep Guide

Structural isomers are specifically characterized by differing arrangements of atoms within the same molecular formula. This distinct feature sets them apart from other types of isomers, such as stereoisomers, which have the same connectivity of atoms but differ in the spatial arrangement of those atoms.

The essence of structural isomers lies in the fact that they can have different chemical properties due to their unique structures, even though they share the same molecular formula. For example, the structural isomers butane and isobutane have the same molecular formula (C4H10), yet they exhibit differences in boiling points and other physical properties due to their different structures. Thus, the correct response highlights the fundamental defining characteristic of structural isomers.