Homologous Series

Edexcel AS-level ChemistryIntroduction to Organic ChemistryLesson 6 of 13

A homologous series is a family of organic compounds that:

1. have the same functional group;
2. have the same general formula;
3. differ from the next member by a CH₂ group;
4. have similar chemical properties;
5. show a gradual trend in physical properties, such as boiling point.

The chemical properties are similar because the functional group, which decides the reactions, is the same in every member. The physical properties change gradually because each extra CH₂ adds electrons, so the London forces between molecules get stronger and the boiling point rises.

More in Introduction to Organic Chemistry

• Saturated and Unsaturated Hydrocarbons
• Cyclic Compounds
• Types of Formulae
• Functional Groups
• Naming Organic Compounds
• Practice Question - 1
• Practice Question - 2
• Practice Question - 3

All 13 lessons in Introduction to Organic Chemistry · All Edexcel AS-level Chemistry topics