By David Fowkes on Friday, 12 October 2018
Category: IGCSE Chemistry

4.19 - 4.22 Alkanes

 4.19 Some saturated hydrocarbons

The Alkane series is a family of hydrocarbons.  The technical name for this sort of  "family" is a "homologous series" The alkane molecules contain atoms of hydrogen and carbon only.

The general formula for the alkanes is CnH2n+2

​Assumed background knowledge

 4.19- 4.21 Activity 1. From one to ten

 Students should:

  • 4.19 know the general formula for alkanes
  • 4.20 explain why alkanes are classified as saturated hydrocarbons
  • 4.21 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

 4.22 Activity 2. Time for a substitution

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 Students should:

  • 4.22 describe the reactions of alkanes with halogens in the presence of ultraviolet radiation, limited to mono-substitution knowledge of reaction mechanisms is not required

Here we look at the way alkanes react with halogens ( for example Chlorine Cl2). When chlorine is mixed with methane ( CH4 ) nothing happens until the mixture is irradiated with ultraviolet radiation.

Study the animation before answering the questions below: