Alkanes (Edexcel IGCSE Chemistry)
Exam board Pearson Edexcel · IGCSEUpdated 2024-10-23
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The Alkanes
Spec point — know the general formula for alkanes explain why alkanes are classified as saturated hydrocarbons understand how to draw the structural and displayed formulae for alkanes with up to five carbon atoms in the molecule, and to name the unbranched-chain isomers
Alkanes
What are alkanes?
- Alkanes are a group of saturated hydrocarbons
- The term saturated means that they only have single carbon-carbon bonds, there are no double bonds
- The general formula of the alkanes is CnH2n+2
- Alkanes are generally unreactive compounds but they do undergo combustion reactions, can be cracked into smaller molecules and can react with halogens in the presence of light
- Methane is an alkane and is the major component of natural gas
Table of alkanes
| Displayed formula | Name | Molecular formula |
|---|---|---|
 | methane | CH4 |
 | ethane | C2H6 |
 | propane | C3H8 |
 | butane | C4H10 |
 | pentane | C5H12 |
The first five members of the alkane homologous series
Exam Hint For your exam, you need to be able to name, draw and give the appropriate formula for the first five alkanes.
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