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Alkenes
This topic develops unsaturated hydrocarbon chemistry through double-bond reactivity.
12
Objectives
10
Flashcards
10
Questions
90 min
Study time
AqaA LevelChemistryOrganic chemistry
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Syllabus checklist
What you need to know
12 objective pages available
Structure, bonding and reactivity4 objectives
- Describe alkenes as unsaturated hydrocarbons.
- Explain bonding in alkenes using sigma and pi bonds.
- Explain why the C=C bond is attacked by electrophiles.
- Use bromine water to test for unsaturation.
Electrophilic addition4 objectives
- Outline electrophilic addition to alkenes with hydrogen bromide.
- Explain carbocation formation and stability where appropriate.
- Predict major products from addition to unsymmetrical alkenes.
- Outline hydration of alkenes to alcohols.
Addition polymers4 objectives
- Draw repeat units from alkene monomers.
- Identify monomers from addition polymer repeat units.
- Explain addition polymerisation as repeated addition across C=C bonds.
- Distinguish addition polymers from condensation polymers.
Key terms
Unsaturated HydrocarbonAddition ReactionElectrophilic additionHybridizationElectrophileBrominationMarkovnikov ruleCarbocationNucleophileMonomerPolymerizationRepeat unit
Exam tips
- Use structural diagrams: When describing alkenes, include structural diagrams to illustrate the presence of double bonds.
- Draw structural diagrams: When explaining reactions involving alkenes, draw structural diagrams to illustrate the bonds and the reaction mechanism.
Common mistakes
- Confusing alkenes with alkanes: Remember that alkenes are unsaturated due to the presence of double bonds, while alkanes are saturated with only single bonds.
- Confusing sigma and pi bonds: Remember that sigma bonds are formed by head-on overlaps and allow rotation, while pi bonds are formed by sideways overlaps and restrict rotation.
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