This topic summary covers Knowledge Organiser: Polymers within Polymers for GCSE Chemistry. Revise Polymers in Organic Chemistry for GCSE Chemistry with 20 exam-style questions and 14 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 15 of 15 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Knowledge Organiser: Polymers
Key Terms
- Monomer — small repeating unit
- Polymer — large molecule of monomers
- Addition polymerisation — alkenes, no by-product
- Condensation polymerisation — two functional groups, water released
Drawing Polymers
- Double bond → single bond
- Add continuation lines at ends
- Put in square brackets
- Add subscript n
Addition vs Condensation
- Addition: one product only (polymer)
- Condensation: polymer + H₂O
- Addition uses alkenes (C=C)
- Natural polymers = condensation
Exam Checklist
- Continuation lines = essential
- n subscript = must include
- Addition ≠ water released
- Not all polymers are plastics
Key Equations
- n(CH₂=CH₂) → (−CH₂−CH₂−)ₙ (addition polymerisation of ethene)
- Condensation: diol + dicarboxylic acid → polyester + nH₂O
- Repeat unit: monomer structure with C=C replaced by C−C and brackets
Common Mistakes
- Drawing the repeat unit with a double bond still in it: In addition polymerisation the C=C opens — the repeat unit must show only single bonds with continuation lines through the brackets
- Forgetting the subscript n: The n outside the bracket indicates many repeating units — omitting it is an error that loses marks
- Saying addition polymerisation produces water: Addition polymerisation produces ONLY the polymer — condensation polymerisation releases water as a by-product
- Confusing natural and synthetic polymers: Proteins and DNA are natural condensation polymers; poly(ethene) and PVC are synthetic addition polymers
Practice questions for Polymers
What type of monomers are needed for addition polymerisation?
Explain how addition polymerisation works. Include the role of the double bond.
Quick recall flashcards
What is a polymer?
A large molecule made up of many repeating units (monomers) joined together
What is a monomer?
A small molecule that can be joined together to form a polymer