Structural isomers, also known as constitutional isomers, are compounds that have the same molecular formula but different structural arrangements of atoms. This means that the atoms are bonded together in a different order, resulting in distinct chemical compounds with different properties and characteristics. There are several classes of structural isomers, including skeletal isomers, positional isomers (or regioisomers), functional isomers, tautomers, and structural topoisomers/Fundamentals/Isomerism_in_Organic_Compounds/Structural_Isomerism_in_Organic_Molecules)/Chapters/Chapter_5%3A_Properties_of_Compounds/5.1%3A_Isomers).
For example, in the case of alkanes, structural isomers can arise due to the possibility of branching in carbon chains, leading to different arrangements of the carbon atoms. Additionally, functional group isomerism occurs when isomers contain different functional groups, belonging to different families of compounds/Fundamentals/Isomerism_in_Organic_Compounds/Structural_Isomerism_in_Organic_Molecules)/Chapters/Chapter_5%3A_Properties_of_Compounds/5.1%3A_Isomers).
Its important to note that structural isomerism is different from stereoisomerism, where the atoms and bonding scheme are the same, but only the relative spatial arrangement of the atoms is different.
In summary, structural isomers play a significant role in organic chemistry, as they demonstrate the diversity of compounds that can be formed from the same set of atoms, leading to a wide range of chemical and physical properties.
