A-Level Chemistry - Isomerism

Isomer

A molecule that has the same molecular formula but where they are arranged differently

Types of Isomerism

Structural Isomerism and Stereoisomerism

Sub-Divisions of Structural Isomerism

Positional isomerism, functional group isomerism and chain isomerism

Sub-Divisions of Stereoisomerism

E-Z isomerism and optical isomerism (covered in 25.2)

Structural Isomerism

Isomers that have the same molecule formula but different structural formulae

Stereoisomerism

Where two or more compounds have the same structural formula. They differ in the arrangements of the bonds in space

Positional Isomerism (Structural)

The functional group is attached to the main chain at different points

Functional Group Isomerism (Structural)

There are different functional groups

Functional Group Isomerism (Diagram)

Chain Isomerism (Structural)

The hydrocarbon is arranged in a different way

Chain Isomerism (Diagram)

E-Z Isomerism (Stereo)

Tells us about the position of the substituents at either side of the carbon-carbon double bond. They may be on the same side of the bond (Z) or on opposite sides (E)

E-Z Isomerism (Diagram)

Cis-Trans Isomerism

E-Z isomerism for less complex molecules. Z corresponds with cis and E with trans