Describing Alkanes (Edexcel AS Chemistry)

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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 CnH2n+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

An Introduction to AS Level Organic Chemistry Alkanes, downloadable AS & A Level Chemistry revision notes

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

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Richard

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Richard has taught Chemistry for over 15 years as well as working as a science tutor, examiner, content creator and author. He wasn’t the greatest at exams and only discovered how to revise in his final year at university. That knowledge made him want to help students learn how to revise, challenge them to think about what they actually know and hopefully succeed; so here he is, happily, at SME.