1. Section 6
Hydrocarbons

2. What are Hydrocarbons?
A hydrocarbon is a molecule which contains only the elements Carbon and Hydrogen.
Hydrocarbons are obtained from the Fractional Distillation of crude oil.
We use them for fuels in cars (octane) and in cookers (methane).

3. How Do We Group All These Hydrocarbons Together?

4. Hydrocarbons Homologous Series Alkanes Alkenes Cycloalkanes
a group of chemically similar compounds which can be represented by a general formula.
Physical properties change gradually through the series
Alkanes
Alkenes
Cycloalkanes

5. Alkenes X Monsters Ethene Eat Propene Pupils Butene But Pentene Prefer
Hexene Hairy
Heptene Haggis
Octene Or
Nonane Nice
Decane Dinners

6. Alkenes - Ethene 3D Full Structural  2D Full Formula Structural
Get them to make a model of methane to show that it doesn’t sit flat on the table but does in fact have a 3D shape. Also C = 4 bonds and H = 1

7. Alkenes Each member can be represented in three different ways:
Ethene Propene
Full Structural
Formula
Shortened Structural
Molecular Formula

8. Alkenes
The Alkenes are a family of hydrocarbons and all share the same chemical properties:
Double Carbon to carbon bonds
( - C = C - )
All end in -‘ene’
Unsaturated hydrocarbons
All share a General Formula

9. Alkenes -48 -6 C2H4 C4H8 Butene Ethene (2) CH2=CH2 -104 Propene (3)
(Carbon Atoms)
Molecular Formula
Shortened Structural Formula
Full Structural Formula
Boiling
Point
Ethene
(2)
C2H4
CH2=CH2
-104
Propene
(3)
-48
Butene
(4)
C4H8
CH3 = CHCH2CH2 -6

10. Alkenes -48 -6 CH2=CHCH2CH2CH3 Ethene (2) C2H4 CH2=CH2 -104 Propene
(Carbon Atoms)
Molecular Formula
Shortened Structural Formula
Full Structural Formula
Boiling
Point
Ethene
(2)
C2H4
CH2=CH2
-104
Propene
(3)
C3H6
CH2 =CHCH3
-48
Butene
(4)
C4H8
CH2=CHCH2CH2CH3 -6

11. Alkenes 30 63 Pentene (5) Hexene (6) Alkene (Carbon Atoms)
Molecular Formula
Shortened Structural Formula
Full Structural Formula
Boiling
Point
Pentene
(5) 30
Hexene
(6) 63

12. Alkenes 30 63 CH2=CHCH2CH2CH3 Pentene (5) C5H10 Hexene (6) C6H12
(Carbon Atoms)
Molecular Formula
Shortened Structural Formula
Full Structural Formula
Boiling
Point
Pentene
(5)
C5H10
CH2=CHCH2CH2CH3 30
Hexene
(6)
C6H12 63

13. Alkenes 93 123 Heptene (7) Octene (8) Alkene (Carbon Atoms)
Molecular Formula
Shortened Structural Formula
Full Structural Formula
Boiling
Point
Heptene
(7) 93
Octene
(8)
123

14. Alkenes 93 123 CH2=CHCH2CH2 CH2CH2CH3 CH2=CHCH2CH2 CH2 CH2CH2CH3 C7H14
(Carbon Atoms)
Molecular Formula
Shortened Structural Formula
Full Structural Formula
Boiling
Point
Heptene
(7)
C7H14
CH2=CHCH2CH2 CH2CH2CH3 93
Octene
(8)
C8H16
CH2=CHCH2CH2
CH2 CH2CH2CH3
123

15. General Formula for alkenes is CnH2n
The number of Hydrogen atoms = 2 times the number of Carbon atoms
General Formula for alkenes is CnH2n

16. Properties of Alkenes Physical Properties Chemical Properties
The alkenes increase in size
Their melting and boiling points increase down the group
Chemical Properties
All burn completely to produce carbon dioxide and water
Undergo addition reactions

17. Uses of Alkenes Making polymers (plastics)
Industrial production of ethanol