AQA · GCSE · Chemistry

    Course version: 8462 · Version from Sept 2018

    Students should be able to: recognise addition polymers and monomers from…

    Full specification wording

    Addition polymerisation: Students should be able to: recognise addition polymers and monomers from diagrams in the forms shown and from the presence of the functional group C=C in the monomers draw diagrams to represent the formation of a polymer from a given alkene monomer relate the repeating unit to the monomer. AQA GCSE Chemistry 8462. GCSE exams Jun

    Monomers are alkenes and contain the C=C functional group; polymers are long-chain saturated molecules made of repeating units.

    Checked against the AQA 8462 specification (opens in a new tab) on .

    • Point 4 of 4
    • 4 key terms

    Study notes

    From the checked teaching notes for this specification point.

    The idea

    Monomers are alkenes and contain the C=C functional group; polymers are long-chain saturated molecules made of repeating units. When drawing the formation of a polymer from a given alkene monomer, show the monomer with its C=C double bond, then show the repeating unit with single bonds and extension bonds. The repeating unit must have the same atoms as the monomer. For example, propene, CH₂=CHCH₃, forms poly(propene) with the repeating unit –CH₂–CH(CH₃)–. To relate the repeating unit to the monomer, identify the two carbon atoms that were part of the double bond and note that they now form single bonds to neighbouring units. Practise converting between monomer and repeating unit diagrams accurately.

    What earns the marks

    • Recognise the C=C double bond as the functional group present in monomers for addition polymerisation.
    • Identify addition polymers from diagrams showing a saturated carbon chain with repeating units.
    • Draw the formation of a polymer from a given alkene by opening the double bond and joining monomers.
    • Draw the repeating unit of a polymer from a given monomer, ensuring the same atoms are present.
    • Relate the repeating unit to the monomer by identifying the carbon atoms that were double-bonded and now form single bonds.
    • Use correct notation for repeating units, including brackets and extension bonds.

    Common mistakes and how to put them right

    • Confusing addition and condensation polymers.

      Put it right by checking that the monomer contains C=C and that no small molecule is eliminated.

    • Drawing the repeating unit with the double bond still present.

      Put it right by showing only single bonds between carbon atoms.

    • Forgetting to include side groups such as CH₃ in the repeating unit.

      Put it right by copying all atoms from the monomer into the repeating unit.

    Exam tips

    • When given a diagram of a polymer, work backwards to identify the monomer by finding the repeating unit and restoring the C=C double bond.
    • Always check that the number of each type of atom in the repeating unit matches the monomer.
    • Practise drawing repeating units for common monomers such as ethene, propene and chloroethene.

    Try the lesson

    The start of the Addition polymerisation: Students should be able to: recognise addition polymers and monomers from diagrams in the forms shown and from the presence of the functional group C=C in the monomers draw diagrams to represent the formation of a polymer from a given alkene monomer relate the repeating unit to the monomer. AQA GCSE Chemistry 8462. GCSE exams Jun lesson, made from checked teaching notes for this specification point.

    Have a go first

    Which functional group must be present in a molecule for it to act as a monomer in addition polymerisation?

    Listen

    Monomers are alkenes and contain the C=C functional group; polymers are long-chain saturated molecules made of repeating units. When drawing the formation of a polymer from a given alkene monomer, show the monomer with its C=C double bond, then show the repeating unit with single bonds and extension bonds. The repeating unit must have the same atoms as the monomer. For example, propene, CH₂=CHCH₃, forms poly(propene) with the repeating unit –CH₂–CH(CH₃)–. To relate the repeating unit to the monomer, identify the two carbon atoms that were part of the double bond and note that they now form single bonds to neighbouring units. Practise converting between monomer and repeating unit diagrams accurately. A strong answer earns marks for these points. Recognise the C=C double bond as the functional group present in monomers for addition polymerisation. Identify addition polymers from diagrams showing a saturated carbon chain with repeating units. Draw the formation of a polymer from a given alkene by opening the double bond and joining monomers. Draw the repeating unit of a polymer from a given monomer, ensuring the same atoms are present. A common slip: Confusing addition and condensation polymers. Instead, checking that the monomer contains C=C and that no small molecule is eliminated. Exam tip: When given a diagram of a polymer, work backwards to identify the monomer by finding the repeating unit and restoring the C=C double bond.

    See it

    A top-to-bottom flowchart with eight boxes. The first box says the alkene monomer contains C=C. An arrow leads to a box saying open the C=C double bond, then to a box saying join monomers together, then to a box saying polymer forms with repeating units. From there an arrow leads to a box saying the repeating unit has single bonds only, then to a box saying the repeating unit has the same atoms as the monomer, then to a box saying identify the two carbons that were double-bonded, and finally to a box saying those carbons now form single bonds to neighbouring units.
    Shows how an alkene monomer with a C=C double bond forms an addition polymer whose repeating unit has single bonds and the same atoms as the monomer.

    Put it in order

    Put these steps in the order they happen.

    1. 1. Repeating unit has single bonds only
    2. 2. Those carbons now form single bonds to neighbouring units
    3. 3. Repeating unit has same atoms as monomer
    4. 4. Alkene monomer contains C=C
    5. 5. Open the C=C double bond
    6. 6. Identify the two carbons that were double-bonded
    7. 7. Join monomers together
    8. 8. Polymer forms with repeating units

    Key words

    Say what each word means before you turn the card.

    monomer

    Try answering aloud or in your head before turning the card.

    addition polymer

    Try answering aloud or in your head before turning the card.

    repeating unit

    Try answering aloud or in your head before turning the card.

    C=C

    Try answering aloud or in your head before turning the card.

    See every definition
    monomer
    An alkene that contains the functional group C=C and from which an addition polymer is formed.
    addition polymer
    A long-chain saturated molecule made of repeating units, recognised from diagrams showing a saturated carbon chain.
    repeating unit
    The part of a polymer that must have the same atoms as the monomer, shown with single bonds and extension bonds.
    C=C
    The functional group present in monomers for addition polymerisation, shown as a double bond between carbon atoms.

    Label the diagram

    Some boxes have lost their names. Pick the right name for each number.

    The diagram again, with 3 boxes numbered instead of named. A top-to-bottom flowchart with eight boxes. The first box says the alkene monomer contains C=C. An arrow leads to a box saying open the C=C double bond, then to a box saying join monomers together, then to a box saying polymer forms with repeating units. From there an arrow leads to a box saying the repeating unit has single bonds only, then to a box saying the repeating unit has the same atoms as the monomer, then to a box saying identify the two carbons that were double-bonded, and finally to a box saying those carbons now form single bonds to neighbouring units.

    • 1Box 1

    • 2Box 2

    • 3Box 3

    0 of 3 labelled

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    Test your understanding of Addition polymerisation: Students should be able to: recognise addition polymers and monomers from diagrams in the forms shown and from the presence of the functional group C=C in the monomers draw diagrams to represent the formation of a polymer from a given alkene monomer relate the repeating unit to the monomer. AQA GCSE Chemistry 8462. GCSE exams Jun

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