1. Title: Alkanes and Alkenes Complete the activities listed below
15/05/2019
Lesson aim: Know how to name and draw alkanes and alkenes. Understand the difference between the 2.
Write down the date, title and lesson aim.
Write down the keywords from below.
What is similar/different between these 2 structures? H C H C
Key words: Hydrocarbon, saturated, unsaturated, double bond, molecular formula, displayed formula, structural formula.

2. Learning Outcomes
15/05/2019
A*/A: Represent alkanes and alkenes using molecular, structural and displayed formulae – making use of general formulae.
A/B: Understand how to name and draw both alkanes and alkenes.
B/C: Describe the similarities and differences between alkanes and alkenes.
Key words: Hydrocarbon, saturated, unsaturated, double bond, molecular formula, displayed formula, structural formula.

3. Hydrocarbons 15/05/2019 These two molecules are HYDROCARBONS. Why?
Ethane
Ethene H C H C
Hydrocarbons are molecules/compounds that contain ONLY atoms of HYDROGEN and CARBON!

4. What is a hydrocarbon then? Write your own definition of this keyword
Hydrocarbon or not?
What is a hydrocarbon then?
Write your own definition of this keyword
1,2,4 are hydrocarbons

5. AlkANE or alkENE? All alkanes end in ….ane All alkenes end in ….ene
15/05/2019
All alkanes end in ….ane
All alkenes end in ….ene
The first part of the name tells you how many carbon atoms it has:
Meth = 1 Hex = 6
Eth = 2 Hept = 7
Prop = 3 Oct = 8
But = 4 Non = 9
Pent = 5 Dec = 10

6. AlkANE or alkENE? All alkanes end in ….ane (no double bonds)
15/05/2019
All alkanes end in ….ane (no double bonds)
All alkenes end in ….ene (1 or more double bonds)
Name the hydrocarbon that…
Contains 3 carbons and no double bonds
Contains 7 carbons and 1 double bond.
Contains 1 carbon and no double bonds.
Contains 2 carbons and has 1 double bond.
Contains 5 carbons and has 1 double bond.
Contains 5 carbons and no double bonds.
Propane
Heptene
Methane
Ethene
Pentene
Pentane

7. Saturated/Unsaturated
15/05/2019
All alkanes have only a single covalent bond between the carbons. They are called SATURATED because they have no spare bonds.
All alkenes have at least one carbon-to-carbon double bonds (C=C). This means they are UNSATURATED. H C
This is ethane:
C2H6
General Formula: CnH2n+2
General Formula: CnH2n H C
This is ethene:
C2H4

8. Saturated/Unsaturated
15/05/2019 H C
Contains 1 carbon.
Contains 3 carbons.
Contains 6 carbons.
Contains 547 carbons.
CH4
C3H8
C6H14
C547H1096
General Formula: CnH2n+2
General Formula: CnH2n
Contains 3 carbon2.
Contains 4 carbons.
Contains 8 carbons.
Contains 547 carbons.
C3H6
C4H8 H C
C8H16
C547H1094

9. Review 15/05/2019 All (Grade C) Most (Grade B) Some ( Grade A/A*)
Distinguish between an alkane and an alkene
Draw the structures and write the formulae for alkanes and alkenes
Analyse substances to identify whether they are saturated or unsaturated

10. Build a simple Hydrocarbon
15/05/2019
Use 1 carbon only.
Can you draw it?
What is the formula of the compound?
How about its name?
Methane

11. More Structures 15/05/2019 Build…
Draw (displayed, structural and molecular formulae)…
And Name all alkanes and alkenes containing 1-5 carbons.
Note: For a double bond you need to use 2 of the longer “bendy bonds”.
EXT: Can you work out a general formula for alkanes?
What is the ratio of Carbon to Hydrogen?
How about alkenes?

12. Name these alkanes. Give their formula.
15/05/2019
Methane
Butane
CH4
C4H10
CH3CH2CH2CH3
Ethane
C2H6
Pentane
CH3CH3
C5H12
CH3CH2CH2CH2CH3
Propane
C3H8
CH3CH2CH3

13. Name these alkenes. Give their formula.
15/05/2019
Name these alkenes. Give their formula.
Ethene
Butene
C2H4
C4H8
CH2=CH2
CH3CH2CH=CH2
Pentene
C5H10
Propene
C3H6
CH3CH2CH2CH=CH2
CH3CH=CH2

14. Testing for unsaturation
15/05/2019
We can use bromine water to test whether or not a substance is saturated (has only C-C bonds) or unsaturated (has 1 or more C=C bonds).
Bromine water STARTS OFF orange in colour and will either:
Decolourise, becoming colourless like water (reaction happens).
Stay orange – if no reaction takes place.
To do:
Copy the table below.
Complete the table whilst watching:
Which hydrocarbon? (A-D)
Observation made
Saturated or unsaturated?
Cyclohexene
Cyclohexane

15. Testing for unsaturation
15/05/2019
We can use bromine water to test whether or not a substance is saturated (has only C-C bonds) or unsaturated (has 1 or more C=C bonds).
Bromine water STARTS OFF orange in colour and will either:
Decolourise, becoming colourless like water (reaction happens).
Stay orange – if no reaction takes place.
To do:
Copy the table below.
Complete the table whilst watching:
Which hydrocarbon? (A-D)
Observation made
Saturated or unsaturated?
Cyclohexene
Orange bromine decolourised
Unsaturated
Cyclohexane
Orange bromine colour remained
Saturated

16. Questions Ethene How can you tell that a reaction has happened?
The diagram below shows what happens to the bromine molecules during this reaction. Use the diagram to help you explain why unsaturated (at least 1x C=C) molecules decolourise bromine water but not saturated (contains no C=C) Molecules.
Ethene

17. Questions Ethene How can you tell that a reaction has happened?
There is a colour change when a reaction happens. (Orange  Colourless)
The diagram below shows what happens to the bromine molecules during this reaction. Use the diagram to help you decide whether it is saturated (C-C only) molecules or unsaturated (contains at least 1x C=C) that cause bromine water to decolourise.
It has to be unsaturated molecules. The C=C bond is broken by the bromine. One bromine atom from Br2 adds on to each carbon from C=C. The Br2 is used up, so bromine water stops being orange.
Ethene

18. Have a go at these exam questions!
8 minutes max.

20. Review 15/05/2019 All (Grade C) Most (Grade B) Some ( Grade A/A*)
Distinguish between an alkane and an alkene
Draw the structures and write the formulae for alkanes and alkenes
Analyse substances to identify whether they are saturated or unsaturated