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Alkanes and alkenes – The reactions of alkenes
Lesson 2 of 3
Specification links
Link to GCSE specification
Suggested time allowed (includes contact and non-contact time):
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
100 minute lesson. The mechanism part could be moved to the
beginning of another lesson, or the question practice (plenary)
given as homework.
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OCR A
o F322: Chains, energy and resources
(2.1.1, 2.1.2 and 2.1.3)
OCR B (Salters)
o F332: Chemistry of Natural
Resources (Polymer revolution j, l)
Edexcel
o Unit 1 – Topic 3 (d, e, f)
AQA
o Unit 2 (3.2.9) - Alkenes
GCSE Science
o (ii) Chemical and material behaviour
o (iv) Environment, Earth and Universe
 GCSE Additional Science
o (ii) Chemistry
 (a) Structure and Bonding
 (b) Chemical Synthesis
Learning outcomes (taken from OCR A)
Students should be able to:
 Describe addition reactions of alkenes (e.g. ethene, propene), with:
o hydrogen in the presence of a suitable catalyst i.e. nickel, to form alkanes
o halogens to form dihalogenoalkanes, including the use of Br 2 as a test for
unsaturation
o hydrogen halides to form halogenoalkanes
o steam in the presence of an acid catalyst to form alcohols
 Define an electrophile as an electron pair acceptor
 Describe how heterolytic fission leads to the mechanism of electrophilic addition in alkenes
Key words
Alkane, alkene, bromine water, addition, electrophile, electrophilic addition, diol, reduction,
heterolytic fission, dihalogenoalkane, halogenoalkane, mechanism
AfL
Suggested teaching order
1.
2.
3.
4.
5.
6.
7.
8.
Starter – 2 min recap of alkanes (all you know; 2 mins)
Introduction of practical scenario (10 mins)
Pupils carry out practical work (25 mins)
Recap of results and steps carried out (10-15 mins)
Draw out summary chart of reactions (5-10 mins)
Mechanism ppt and activities (15 mins)
Plenary - Question practice (10-15 mins)
Plenary – Peer assessment of answers (5 mins)
How Science Works

Use whatever examples you feel are appropriate
Peer assessment of question practice answers.
Mechanism activity indicates level of understanding of these
reactions, and general chemical concepts.
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Lesson 2 of 3
Active Approaches and How you intend to make the subject relevant
(S = Starter activities, M = Main activities, P = Plenary activities)
ICT activities
S = mini whiteboards

M = student-led
learning of reactions
M = Connection to
industrial setting
P = Exam question
practice, with peer
assessment
None
Suggested starter activities
Equipment/Resources
Teacher rationale/notes
1. Recap all you have learnt to date about alkanes from last
lesson
Mini whiteboards
You could make it as a mini competition, or get each
person/group to focus on a specific area. You can introduce
the similarities/differences between alkanes and alkenes.
Suggested main activities
Equipment/Resources
Teacher rationale/notes
1. Practical scenario
Cards and instructions, cyclohexene, Br2,
acidified dilute KMnO4, test tubes, test
tube racks, pipettes, H2SO4, ethanoic acid
See attached notes.
Independent learning.
2. Recap and problem solving (if necessary)
Whiteboard
3. Draw summary chart
Paper/exercise books (template?)
4. Mechanism ppt and discussion
Powerpoint, whiteboard
The pupils stick on the curly arrows and charges for the
mechanism to the board using blu-tack (see teacher’s
notes).
Suggested plenary activities
Equipment/Resources
Teacher rationale/notes
1. Question practice
Past paper questions - 8a,b,d,e from
January 2012 F322 OCR A Paper (in
folder)
Practice can be carried out in pairs/groups or individually.
2. Review of answers – peer assessment
Mark scheme (in folder)
Pupils assess each other’s answers. See what the examiner
is requiring for a good answer.
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Lesson 2 of 3
Homework suggestions

If lesson is shorter than 100 minutes, you can set the practice questions as homework
Cross-curriculum links
N/A
Stretch and Challenge
Extension activity involves pupils thinking about separation of mixtures to obtain the desired product cleanly. They will need to think about exploiting the natural properties
of the compounds in order to do this.
Potential misconceptions
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Notes
I’ve written some information in the teacher’s notes, hopefully this is helpful. I’ve included some arrows and charges for the ppt activity, you can use them if you want (for
the pupils to blu-tack onto the board in the right places). Alternatively, they could draw on the board with a pen.
Nuffield Advanced Chemistry students book (I used fourth edition) is good, it has some examples of these reactions and practical instructions. Most schools seem to have
some of these floating around. See p. 196-201, with experiment 8.4b on p. 196. Summary chart taken from p. 201.
The reaction to produce diols (on the cards) is technically only for Edexcel, but I think it’s good to expose them to lots of reactions, and they need this for the practical.
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