2.1 - Systematic Carbon Chemistry

Systematic Carbon Chemistry

Higher Chemistry 2.1

A homologous series is a family of hydrocarbons with the same general formula and similar chemical properties that show a gradual change in physical properties.

The homologous series from National 5 are:

• alkanes
• alkenes
• cycloalkanes

The alkanes have a general formula of C_nH_2n+2  and don't have a functional group.

The alkenes have a general formula of C_nH_2n  and can be identified by their double bond between the carbons. 

The cycloalkanes have a general formula of C_nH_2n  and can be identified by their shape - a ring of single-bonded carbons. 

All three hydrocarbon families show the same trends in boiling points. As the molecule increases in size, the boiling points also increase. This can be explained by the London dispersion forces between the molecules…