A polymer is a long chain built from repeating units, and its properties follow from the structure of that chain. The lessons here run from the reaction, to the unit, to the properties, to the real-world decision.
This section is part of SPM Chemistry. It connects to carbon compounds, which supplies the monomers.
How do the parts connect?
The lessons follow a chain of four questions.
- How are the monomers joined? Addition and condensation give different products.
- What is the repeating unit, and how long is the chain?
- How does the chain structure affect strength, flexibility and heat behaviour?
- Is the polymer a good choice once cost and waste are considered?
Each answer feeds the next one, so a gap in the first step shows up in the last.
One short example
Ethene, CH₂=CH₂, has a double bond. In addition polymerisation the double bond opens, and thousands of molecules join end to end into poly(ethene). The repeating unit is –CH₂–CH₂–, with no double bond left.
A sample of polymer with a relative molecular mass of 28 000 therefore has 28 000 ÷ 28 = 1000 repeating units. That one example touches the reaction, the unit and the chain length.
Who should start where?
Choose by the difficulty you notice most.
| Your difficulty | Start with |
|---|---|
| Not sure which type of polymerisation a reaction is | distinguishing addition and condensation polymerisation |
| Drawing the repeating unit from a monomer | identifying repeating units |
| Explaining why a material behaves as it does | connecting polymer structure with properties |
| Questions about uses and waste | evaluating uses and environmental trade-offs from evidence |
When the four feel steady, mix them in the polymers practice set.
To have a teacher build these explanations with you, see online one-to-one Chemistry tuition.