Geometric vs Constitutional Isomers [ENDORSED]

[Kyle_Nakahira_1B]

What is the difference between a geometric isomer and a constitutional isomer?

[Celina N 2H]

Constitutional isomers have atoms that vary in the order in which they are connected in; therefore, constitutional isomers may contain differing bonding patterns or functional groups.

Geometric isomers are based on geometric configuration; they can vary in position around bonds with restricted rotation (i.e., any bonds that are not single bonds) or throughout a ring geometry.

[Michelle_Li_1H]

To add on, both constitutional isomers and geometric isomers have the same molecular formula. However, constitutional formulas have different connectivity such that they can be drawn differently. Geometric isomers on the other hand have the same connectivity but different arrangements in space which would mean different structures and compounds.

Examples of constitutional isomers would be the three different structures of C5H12, while geometric isomers for 2-pentene (C5H10) would be trans-2-pentene and cis-2-pentene.

The OChem textbook discusses this in more detail on pages 10 and 14.

Hope this helps!