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Cambridge International AS Level Chemistry

Alkenes

Alkenes are unsaturated hydrocarbons containing a carbon-carbon double bond. These pages separate the topic into how alkenes are made, their bonding and isomerism, the electrophilic addition mechanism, their reactions, and the polymers formed from them.

Alkene bonding and geometrical isomerism sit in Topic 13 and polymers in Topic 20, and are linked from these pages.

Exam Papers
Papers 1 & 2
9701/1 and 9701/2 (AS Level)
Learning Outcomes
14.1.1 – 14.2.5
6 points covered
Sub-topics
8 lessons
Revision notes available
Exam Board
Cambridge
CIE 9701 (2025-2027)

Revision Notes

8 revision notes, in the order the specification teaches them.

A small molecule lost as a second bond forms
1

Producing Alkenes

Elimination from halogenoalkanes with ethanolic NaOH, dehydration of alcohols and cracking of alkanes (14.2.1).

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Orbital picture of a carbon-carbon double bond, with a sigma bond between the atoms and a pi bond above and below
2

Alkene Bonding

The σ and π bonds of the C=C double bond, sp2 hybridisation and the planar alkene (Topic 13.3).

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Two arrangements around a locked double bond that cannot rotate
3

Geometric Isomerism

Restricted rotation about the C=C bond and geometrical (cis/trans) isomerism (Topic 13.4).

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A positive particle attracted towards the electron-rich double bond
4

Electrophilic Addition Mechanism

How electrophiles attack the π bond, carbocation intermediates, the inductive effect and Markovnikov addition (14.2.4, 14.2.5).

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One addition leading to a major and a minor product
5

Markovnikov Addition

Understand the inductive effect of alkyl groups, carbocation stability and why HBr adds to propene to give mainly 2-bromopropane.

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A double bond linked to the reagents it reacts with
6

Reactions of Alkenes

Addition of hydrogen, halogens, hydrogen halides and steam, the bromine water test and oxidation by KMnO4 (14.2.2, 14.2.3).

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Small units joining into one long polymer chain
7

Polymerisation Reactions

Addition polymerisation of ethene, propene and chloroethene, repeat units and monomers (14.2.2, Topic 20).

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Plastic buried in the ground and an incinerator with a chimney filter
8

Polymer Waste

The difficulty of disposing of poly(alkene)s: non-biodegradability and harmful combustion products (Topic 20).

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Summary Map

Download, print and revise the reactions of this topic at a glance.

Summary map

Download, print and revise the reactions of this topic at a glance.

Illustration of a summary map: compounds joined by reaction arrows
Summary map · PDF

Alkenes Map

Cambridge International AS & A Level Chemistry · Topic 14 Hydrocarbons

Every reaction on one A4 page: reagents, conditions and reaction type for each arrow, colour coded, with the key tests.

Download the map7 reactions · A4 landscape · print ready

© 2026 Online Learning System. For personal study: printing is allowed; editing, copying and redistribution are not.

Virtual Lessons

Recorded video lessons that teach the topic step by step.

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MCQ Bank

Multiple-choice papers on this topic, marked the moment you submit.

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SAQ Bank

Written, drawn and worked exam practice on this topic.

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Revision Game

Match reagents to products, free, with your board's reagents and conditions.

Illustration of memory game cards, two turned face up as a matching pairFree

Revision Game: Alkenes

Turn the cards over two at a time: match reagents to what they make, and find how each product is made.

A free memory game on the reactions in this topic, with your board's reagents, conditions and spec points.

  • Two ways to playMatch each set of reagents to what the reaction makes, or see a product and find the reactant and reagents that make it.
  • Drawn the way the exam draws themEvery structure is drawn in ChemDraw, with the reagents and conditions your exam board asks for.
  • It countsRounds earn XP and keep your streak going, and every correct match shows in your KASP analytics, apart from your marks.

Study Cards

Pick a deck, then turn each card to check what you remember.

Specification

Every specification point in this topic, in the exam board's own words. Rate how confident you are with each one.

Official Cambridge documentsSyllabus (opens the Cambridge website in a new tab)

Cambridge no longer issues a data booklet: the data you need are given in each question, and the syllabus has a Data section.

Self-assessment · 18 points

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14.1.1

  1. a

    recall the reaction (reagents and conditions) by which alkanes can be produced: addition of hydrogen to an alkene in a hydrogenation reaction, H2(g) and Pt/Ni catalyst and heat

    Revise

14.2.1

  1. a

    recall the reaction (including reagents and conditions) by which alkenes can be produced: elimination of HX from a halogenoalkane by ethanolic NaOH and heat

    Revise
  2. b i

    recall the reaction (including reagents and conditions) by which alkenes can be produced: dehydration of an alcohol, by using a heated catalyst (e.g. Al2O3)

    Revise
  3. b ii

    recall the reaction (including reagents and conditions) by which alkenes can be produced: dehydration of an alcohol, by using a concentrated acid (e.g. concentrated H2SO4)

    Revise
  4. c

    recall the reaction (including reagents and conditions) by which alkenes can be produced: cracking of a longer chain alkane

    Revise

14.2.2

  1. a (i)

    describe the electrophilic addition of hydrogen to alkenes in a hydrogenation reaction, H2(g) and Pt/Ni catalyst and heat

    Revise
  2. a (ii)

    describe the electrophilic addition of steam to alkenes, H2O(g) and H3PO4 catalyst

    Revise
  3. a (iii)

    describe the electrophilic addition of a hydrogen halide, HX(g), to alkenes at room temperature

    Revise
  4. a (iv)

    describe the electrophilic addition of a halogen, X2, to alkenes

    Revise
  5. b

    describe the oxidation of alkenes by cold dilute acidified KMnO4 to form the diol

    Revise
  6. c i

    describe the oxidation of alkenes by hot concentrated acidified KMnO4 leading to the rupture of the carbon–carbon double bond

    Revise
  7. c ii

    use the identities of the products of oxidation by hot concentrated acidified KMnO4 to determine the position of alkene linkages in larger molecules

    Revise

14.2.3

  1. 14.2.3

    describe the use of aqueous bromine to show the presence of a C=C bond

    Revise

14.2.4

  1. a

    describe the mechanism of electrophilic addition in alkenes, using bromine/ethene as an example

    Revise
  2. b

    describe the mechanism of electrophilic addition in alkenes, using hydrogen bromide/propene as an example

    Revise

14.2.5

  1. a

    describe and explain the inductive effects of alkyl groups on the stability of primary, secondary and tertiary cations formed during electrophilic addition

    Revise
  2. b

    use the inductive effects of alkyl groups on the stability of primary, secondary and tertiary cations to explain Markovnikov addition

    Revise

16.1.1

  1. a

    recall the reaction (reagents and conditions) by which alcohols can be produced: electrophilic addition of steam to an alkene, H2O(g) and H3PO4 catalyst

    Revise