Describing Alkanes (Edexcel A Level Chemistry): Revision Note

Describing Alkanes

• Hydrocarbons are compounds containing hydrogen and carbon only

• There are four families of hydrocarbons you should know: alkanes, alkenes, alkynes and arenes

  • Alkanes, alkenes and alkynes can be described as aliphatic

  • Arenes can be described as aromatic

• Alkanes have the general molecular formula C_nH_2n+2 

• They contain only single bonds and are said to be saturated

• Alkanes are named using the nomenclature rule alk + ane

  • The alk portion of the name depends on the number of carbons

    • 1 carbon = meth

    • 2 carbons = eth

    • 3 carbons = prop

    • 4 carbons = but

    • 5 carbons = pent

    • After 5 carbons, the naming of alkanes matches the names of the polygons in Maths

  •  The ane portion of the name suggests single bonds between the carbon atoms

The First Six Members of the Alkane Family

• Alkanes can be linear, branched or cyclic 

  • The key points are that there are no functional groups and only single bonds between the carbon atoms

Alkanes are compounds made up of carbon and hydrogen atoms only and contain no functional group