AQA A-LEVEL CHEMISTRY
COMPREHENSIVE FINAL SCRIPT 2026
FULL ANSWERS GRADED A+
◉ What is the product when water is electrophilically added to an
alkene? Answer: An alcohol
◉ What is an elimination reaction? Answer: One in which a small
molecule leaves the parent molecule
◉ What is an alkene? Answer: An unsaturated hydrocarbon
◉ What is an unsaturated hydrocarbon? Answer: A compound
containing only carbon and hydrogen atoms and containing at least
one carbon carbon double bond
◉ What are van der Waals forces? Answer: Relatively weak
intermolecular forces caused by temporary dipole dipole interaction
◉ What is the general formula for an alkene? Answer: CnH2n
◉ How would you name an alkene given its displayed formula?
Answer: Identify the longest carbon chain
,Identify the position of the carbon carbon double bond
Identify any side chains
◉ What are structural isomers? Answer: Molecules with the same
molecular formula, but with different a structural formula
◉ What are stereoisomers? Answer: Molecules with the same
molecular AND structural formula but a different 3D arrangement of
their atoms in space
◉ What is E-Z isomerism? Answer: The highest priority groups are
on the same side of the double bond
◉ Describe the C=C double bond Answer: Double covalent bond
Planar bond
Area of high electron density
◉ How do you assign the highest priority of groups in E-Z
isomerism? Answer: The highest atomic number closest to the
double bond has the highest priority
If two groups have e.g. Only carbon and hydrogen, then the one with
the most carbon atoms is assigned the highest priority
◉ What are Z isomers? Answer: Molecules where the highest
priority groups are on the same side
,◉ What are E isomers? Answer: Molecules where the highest
priority groups are on opposite sides
◉ What is addition polymerisation? Answer: The reaction by which
alkenes (or substituted alkenes) react with other alkene (or
substituted alkene) molecules to form polymers
◉ What polymer would the monomer ethene form? Answer:
Poly(ethene)
◉ What is a polymer? Answer: A long chain of repeating monomer
units joined together
◉ Why are addition polymers unreactive? Answer: They lack the
reactive carbon-carbon double bond
Which is an area of high electron density
And so vulnerable to electrophilic attack
◉ Why are the intermolecular forces between polymers often
strong? Answer: Chains are often long
Many electrons
Many van der Waals'
, ◉ Explain why a tertiary carbocation forms the major product and a
secondary/primary carbocation forms the minor product Answer:
Tertiary carbocation has more alkyl groups attached
Positive inductive effect
Reduce + charge on carbon
More stable
Remains in reaction mixture for longer so more likely to react with
electrophile
◉ What is an electrophile? Answer: A substance which can accept a
pair of electrons
(electron pair acceptor)
◉ What is a carbocation? Answer: A species which contains a
positive charge on a carbon atom
◉ Describe the mechanism by which HBr is added to ethene
Answer: e-'s move from area of high electron density to delta + H
e-'s in H-Br bond move to delta - Br
Carbocation forms
Lone pair of e-'s on :Br- attracted to C+ HBr has been added across
the double bond
◉ Explain when major and minor products form in electrophilic
addition to unsymmetrical alkenes Answer: Major product formed via
COMPREHENSIVE FINAL SCRIPT 2026
FULL ANSWERS GRADED A+
◉ What is the product when water is electrophilically added to an
alkene? Answer: An alcohol
◉ What is an elimination reaction? Answer: One in which a small
molecule leaves the parent molecule
◉ What is an alkene? Answer: An unsaturated hydrocarbon
◉ What is an unsaturated hydrocarbon? Answer: A compound
containing only carbon and hydrogen atoms and containing at least
one carbon carbon double bond
◉ What are van der Waals forces? Answer: Relatively weak
intermolecular forces caused by temporary dipole dipole interaction
◉ What is the general formula for an alkene? Answer: CnH2n
◉ How would you name an alkene given its displayed formula?
Answer: Identify the longest carbon chain
,Identify the position of the carbon carbon double bond
Identify any side chains
◉ What are structural isomers? Answer: Molecules with the same
molecular formula, but with different a structural formula
◉ What are stereoisomers? Answer: Molecules with the same
molecular AND structural formula but a different 3D arrangement of
their atoms in space
◉ What is E-Z isomerism? Answer: The highest priority groups are
on the same side of the double bond
◉ Describe the C=C double bond Answer: Double covalent bond
Planar bond
Area of high electron density
◉ How do you assign the highest priority of groups in E-Z
isomerism? Answer: The highest atomic number closest to the
double bond has the highest priority
If two groups have e.g. Only carbon and hydrogen, then the one with
the most carbon atoms is assigned the highest priority
◉ What are Z isomers? Answer: Molecules where the highest
priority groups are on the same side
,◉ What are E isomers? Answer: Molecules where the highest
priority groups are on opposite sides
◉ What is addition polymerisation? Answer: The reaction by which
alkenes (or substituted alkenes) react with other alkene (or
substituted alkene) molecules to form polymers
◉ What polymer would the monomer ethene form? Answer:
Poly(ethene)
◉ What is a polymer? Answer: A long chain of repeating monomer
units joined together
◉ Why are addition polymers unreactive? Answer: They lack the
reactive carbon-carbon double bond
Which is an area of high electron density
And so vulnerable to electrophilic attack
◉ Why are the intermolecular forces between polymers often
strong? Answer: Chains are often long
Many electrons
Many van der Waals'
, ◉ Explain why a tertiary carbocation forms the major product and a
secondary/primary carbocation forms the minor product Answer:
Tertiary carbocation has more alkyl groups attached
Positive inductive effect
Reduce + charge on carbon
More stable
Remains in reaction mixture for longer so more likely to react with
electrophile
◉ What is an electrophile? Answer: A substance which can accept a
pair of electrons
(electron pair acceptor)
◉ What is a carbocation? Answer: A species which contains a
positive charge on a carbon atom
◉ Describe the mechanism by which HBr is added to ethene
Answer: e-'s move from area of high electron density to delta + H
e-'s in H-Br bond move to delta - Br
Carbocation forms
Lone pair of e-'s on :Br- attracted to C+ HBr has been added across
the double bond
◉ Explain when major and minor products form in electrophilic
addition to unsymmetrical alkenes Answer: Major product formed via
