Homologous Series
- Homologous series are families or groups of organic compounds that have similar features and chemical properties due to them having the same functional group
- All members of a homologous series have:
- The same general formula
- The difference in the molecular formula between one member and the next is CH2
- Gradation in their physical properties
- Same functional group
- Similar chemical properties
- Gradation in the physical properties of a homologous series can be seen in the trend in boiling points of the alkanes
Boiling Point
A graph of the boiling points of the first eight alkanes showing a gradually increasing trend
- Each alkane has a boiling point that is higher than the one before it
- As the molecules get larger, the intermolecular forces of attraction between the molecules becomes greater as there are more electrons in the molecules and greater surface area contact between them
- This means that more heat is needed to separate the molecules, hence with increasing molecular size there is an increase in boiling point
