Chemistry · Bonding, Structure and Properties of Matter
Polymers
Spec 5.2.2.5📙 Higher
Theory · read, then commit
Polymers are very large molecules made from many small repeating units called monomers, joined into long chains. The joining process is called polymerisation.
🔹Monomer
A small molecule that can join with others — e.g. ethene, CH₂=CH₂.
⛓️Polymer
The long chain formed from thousands of monomers — e.g. poly(ethene).
🔁Repeating unit
Written in brackets with n outside: [—CH₂—CH₂—]ₙ.
Checkpoint · quick check
State what is meant by a monomer.
1Addition polymerisation uses monomers that contain a C=C double bond.
2The double bond opens up — one bond breaks and frees a pair of electrons.
3Those electrons form a new bond to the next monomer.
4The monomers link into a long saturated chain (no double bonds left) — and no atoms are lost.
Checkpoint · quick check
Describe how a polymer forms from monomers.
🧊Solid at room temperature
Long chains and reasonable intermolecular forces keep polymers solid and flexible.
🚫Electrical insulators
No free electrons or ions, so they do not conduct electricity.
🔥Thermoplastic vs thermosetting
Thermoplastics soften when heated and reshape; thermosetting polymers form cross-links and stay hard.
Checkpoint · quick check
Explain why poly(ethene) is a solid at room temperature.
📐 Key Equations
n CH₂=CH₂ → [—CH₂—CH₂—]ₙ (poly(ethene))
Retrieval · Match the Polymer to its Monomer
Test yourself · 7 questions, exam order
⭐Examiner Tip
Don't call a polymer a giant covalent structure. It is a large molecule whose chains are held to each other by weak intermolecular forces — that is why it melts far below diamond, where strong covalent bonds run all the way through. That force difference is where the comparison marks are.
0 of 7 answered
Warm-up · 2 questions
Explain why polymers have much lower melting points than giant covalent structures such as diamond.
Ethene (CH₂=CH₂) can be used to make poly(ethene), but ethane (C₂H₆) cannot. Explain why.
Exam standard · 3 questions
Explain, in terms of the double bond, how addition polymerisation forms poly(ethene) from ethene.
Explain why a polymer with longer chains tends to have a higher melting point than one with shorter chains.
PVC is stiffer and higher-melting than poly(ethene). Suggest why, in terms of intermolecular forces.
Stretch · 2 questions
Explain why melting a polymer does not break the covalent bonds along its chains.
In addition polymerisation, explain why no small molecule is lost when the monomers join together.
Key note · cover it, say it, check it
Revision card · 6 stepsPolymers
01Polymer: long chain of repeating monomer units.
02Addition polymerisation: monomers with C=C double bonds join together.
03Properties depend on chain length and intermolecular forces.
04Solid at room temperature, flexible, insulators.
05Thermoplastic: soften on heating.
06Thermosetting: permanently hard.
Rate your confidence · then let the quiz check it
Be honest — this only has to convince you.
Don't get itGetting thereNailed it
Stuck · ask Mr Badmus AI
Ask about anything on this page.
FIFA for calculations; Higher (⭐) and Triple (🔬) content flagged clearly.