Topic 6 Revision

1. Topic 6 Revision Hydrocarbons are compounds made from hydrogen and carbon only. There a number of different hydrocarbon families or groups. The simplest group of hydrocarbons is called the alkanes. The names of all alkane compounds end in ane, eg methane, propane, butane and octane.

2. Topic 6 Revision Most of the fuels we use are made from alkanes, alkanes burn. methane is the gas we burn at home propane is used in cigarette lighters butane is used for camping or gas barbecues octane is part of the petrol we use to power cars

3. Topic 6 Revision The names and formulae of the first 8 alkanes are;

4. Topic 6 Revision The names and formulae of the first 8 alkanes are;

5. Topic 6 Revision The names and formulae of the first 8 alkanes are;

6. Topic 6 Revision The names and formulae of the first 8 alkanes are;

7. Topic 6 Revision The names and formulae of the first 8 alkanes are;

8. Topic 6 Revision The names and formulae of the first 8 alkanes are;

9. Topic 6 Revision The names and formulae of the first 8 alkanes are;

10. Topic 6 Revision The names and formulae of the first 8 alkanes are;

11. Topic 6 Revision The names and formulae of the first 8 alkanes are;

12. Topic 6 Revision The names and formulae of the first 8 alkanes are;

13. Topic 6 Revision The names and formulae of the first 8 alkanes are;

14. Topic 6 Revision The names and formulae of the first 8 alkanes are;

15. Topic 6 Revision The names and formulae of the first 8 alkanes are;

16. Topic 6 Revision The names and formulae of the first 8 alkanes are;

17. Topic 6 Revision The names and formulae of the first 8 alkanes are;

18. Topic 6 Revision The names and formulae of the first 8 alkanes are;

19. Topic 6 Revision The names and formulae of the first 8 alkanes are; Now learn these!

20. Topic 6 Revision This may help you most elephants prefer bananas perhaps horses hate oranges methane ethane propane butane pentane hexane heptane octane

21. Topic 6 Revision The general formula for the alkanes is CnH2n+2, this helps you work out the molecular formula. The names of the alkanes are listed in order on page 6 of the data booklet, as are the cycloalkanes and the alkenes. If you know the number of carbon atoms (n), then you can work out the number of hydrogen atoms (2n+2).

22. Topic 6 Revision The boiling points of the alkanes show a regular increase as we go from one alkane to the next. As you go from one alkane to the next the difference between the molecules is a –CH2- group. Other physical properties, eg, melting point, density and viscosity also show a regular increase as we go from one alkane to the next.

23. Topic 6 Revision The family of alkanes can also be described as a homologous series. A homologous series is a group of compounds that i have the same general formula, CnH2n+2 for the alkanes ii have similar chemical properties – alkanes burn forming carbon dioxide and water iii show a gradual and regular change from one member to the next.

24. Topic 6 Revision The full structural formula of a compound shows all of the bonds. This is sometimes known as the extended structural formula. Carbon forms 4 bonds and hydrogen forms 1 bond. The full structural formula for methane, CH4, is The full structural formula for ethane, C2H6, is

25. Topic 6 Revision propane, C3H8 butane, C4H10 pentane, C5H12 hexane, C6H14

26. Topic 6 Revision The shortened structural formula of a compound the hydrogen atoms around each individual carbon. The shortened structural formula for methane, CH4, is The shortened structural formula for ethane, C2H6, is The shortened structural formula for propane, C3H8, is The shortened structural formula for butane, C4H10, is

27. Topic 6 Revision pentane, C5H12 hexane, C6H14 heptane, C7H16 octane, C8H18 The carbon atom on either end has 3 hydrogens attached. The carbon atoms in the middle of the structure have 2 hydrogens attached. CH3 CH2 CH2 CH2 CH3

28. Topic 6 Revision The fourth member of the alkane group has the formula C4H10. The full structural formula can be drawn as However another structure can also be drawn Both structures have the formula C4H10.

29. Topic 6 Revision Compounds that have the same molecular formula but a different structure are called isomers. All of the alkanes from carbon 4 upwards have isomeric forms, different structures. C5H12 has three isomers. CH3 CH2 CH2 CH2 CH2 CH3 CH3 CH CH3 CH CH3 CH3 CH3 CH3 CH3

30. Topic 6 Revision Cycloalkanes are another homologous series. Here the carbon atoms are joined in rings. The first member of the series is cyclopropane, three carbons is the smallest ring possible. Cyclobutane has this structure CH2 CH2 CH2 CH2 CH2 H2C CH2

31. Topic 6 Revision cyclopentane cyclohexane The general formula for the cycloakanes is CnH2n. CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2

32. Topic 6 Revision A third homologous series of hydrocarbons is the alkenes. The alkenes are hydrocarbons where there is a double bond between two carbons, eg, ethene Ethene is the first member of the alkene series as it has 2 carbon atoms, you cannot have a double bond between 1 atom. The names of all the alkenes end in ene, eg, ethene, propene and butene. The general formula for the alkenes is CnH2n. CH2 CH2

33. Topic 6 Revision The names, formulae and shortened structural formulae of the alkenes are shown.

34. Topic 6 Revision The names, formulae and shortened structural formulae of the alkenes are shown.

35. Topic 6 Revision The names, formulae and shortened structural formulae of the alkenes are shown. CH2 CH2

36. Topic 6 Revision The names, formulae and shortened structural formulae of the alkenes are shown. CH2 CH2

37. Topic 6 Revision The names, formulae and shortened structural formulae of the alkenes are shown. CH2 CH2

38. Topic 6 Revision The names, formulae and shortened structural formulae of the alkenes are shown. CH2 CH2 CHCH3 CH2

39. Topic 6 Revision The names, formulae and shortened structural formulae of the alkenes are shown. CH2 CH2 CHCH3 CH2

40. Topic 6 Revision The names, formulae and shortened structural formulae of the alkenes are shown. CH2 CH2 CHCH3 CH2

41. Topic 6 Revision The names, formulae and shortened structural formulae of the alkenes are shown. CH2 CH2 CH2 CHCH3 CHCH2CH3 CH2

42. Topic 6 Revision The names, formulae and shortened structural formulae of the alkenes are shown. CH2 CH2 CH2 CHCH3 CHCH2CH3 CH2

43. Topic 6 Revision The names, formulae and shortened structural formulae of the alkenes are shown. CH2 CH2 CH2 CHCH3 CHCH2CH3 CH2

44. Topic 6 Revision The names, formulae and shortened structural formulae of the alkenes are shown. CH2 CH2 CH2 CH2 CHCH3 CHCH2CH3 CHCH2CH2CH3 CH2

45. Topic 6 Revision The names, formulae and shortened structural formulae of the alkenes are shown. CH2 CH2 CH2 CH2 CHCH3 CHCH2CH3 CHCH2CH2CH3 CH2

46. Topic 6 Revision The names, formulae and shortened structural formulae of the alkenes are shown. CH2 CH2 CH2 CH2 CHCH3 CHCH2CH3 CHCH2CH2CH3 CH2

47. Topic 6 Revision The names, formulae and shortened structural formulae of the alkenes are shown. CH2 CH2 CH2 CH2 CH2 CHCH3 CHCH2CH3 CHCH2CH2CH3 CHCH2CH2CH2CH3 CH2

48. Topic 6 Revision The full structural formulae for some of the alkenes are shown. ethene propene butene pentene hexene H H H H H H H H H H H H H H H H H H H H C C C C H H H H C C C C C C C C C C C C C C C C H H H H H H H H H H H H H H H H

49. Topic 6 Revision The difference between an alkane and an alkene is easily seen from the structure. ethane ethene butane butene H H H H H H C H C C C C C H H H H H

50. Topic 6 Revision Cycloalkanes and alkenes are isomers. They have the same molecular formula but different structures. cyclopropene, C3H6 propene, C3H6 H H H C H C C H H CH2 H2C CH2