2. Hydrocarbons A hydrocarbon is a compound containing the elements H and C only.A hydrocarbon is a compound containing the elements H and C only. A Homologous Series is a group of Hydrocarbons with the same General Formula and similar Chemical Properties.A Homologous Series is a group of Hydrocarbons with the same General Formula and similar Chemical Properties.

3. The Alkanes SimplestSimplest group of Hydrocarbons. GeneralGeneral formula – CnH2n+2( CnH2n+2( n= number of Carbon atoms) MainlyMainly used as fuels. HaveHave only Carbon to Carbon single bonds in their structure. ThisThis makes them SATURATED.

4. Alkanes – more info! NameMolecular Formula MethaneCH4 EthaneC2H6 PropaneC3H8 ButaneC4H10 PentaneC5H12 HexaneC6H14 HeptaneC7H16 OctaneC8H18

5. Alkane - Structure

6. Alkenes General Formula C n H 2nGeneral Formula C n H 2n Contain C=C double bonds.Contain C=C double bonds. They are Unsaturated.They are Unsaturated. Again can be used as fuels.Again can be used as fuels. Test – decolourise Bromine water – INSTANTLY!Test – decolourise Bromine water – INSTANTLY! Colour change Brown - ClearColour change Brown - Clear

7. The Names! Alkene Molecular formulaAlkene Molecular formula EtheneC 2 H 4 PropeneC 3 H 6 ButeneC 4 H 8 PenteneC 5 H 10 HexeneC 6 H 12 HepteneC 7 H 14 OcteneC 8 H 16

8. Alkene - Structure

9. Cycloalkanes General formula C n H 2nGeneral formula C n H 2n They are saturated – no double bonds.They are saturated – no double bonds. They have a ring in their structure.They have a ring in their structure. They are isomers with alkenes.They are isomers with alkenes.

10. Cycloalkane - names Name Molecular FormulaName Molecular Formula CyclopropaneCHCyclopropaneC 3 H 6 CyclobutaneCHCyclobutaneC 4 H 8 CyclopentaneCHCyclopentaneC 5 H 10 CyclohexaneCHCyclohexaneC 6 H 12 CycloheptaneCHCycloheptaneC 7 H 14 CyclooctaneCHCyclooctaneC 8 H 16

11. Cycloalkane - Structure

12. Cracking! There are more of the heavier less useful fractions.There are more of the heavier less useful fractions. We can “chop” them up into smaller – more useful ones.We can “chop” them up into smaller – more useful ones. This is called “Cracking”This is called “Cracking” We need heat and a catalyst for this!We need heat and a catalyst for this!

13. Products of Cracking An Unsaturated product (contains double bond) and a Saturated product ( single bonds only) are always formed.An Unsaturated product (contains double bond) and a Saturated product ( single bonds only) are always formed. ExampleExample C 12 H 26 —>C 4 H 8 + C 6 H 14 +C 2 H 4C 12 H 26 —>C 4 H 8 + C 6 H 14 +C 2 H 4

14. Isomers Isomers are compounds with the same molecular formula but a different structural formula.Isomers are compounds with the same molecular formula but a different structural formula. ExampleExample C 4 H 10 – this has 2 isomers.C 4 H 10 – this has 2 isomers. H H H H H CH 3 H H H H H H CH 3 H I I I I I I I I I I I I I I H - C – C – C – C – H and H - C – C – C - HH - C – C – C – C – H and H - C – C – C - H I I I I I I I I I I I I I I H H H H H H H H H H H H H H

15. More Isomers TheThe alkenes and cyclo alkanes are isomers. ExampleExample C 3 H 6C 3 H 6 is the molecular formula for both propene and cyclo propane. TheyThey both have different structures.