Starter quiz
- Which of the following three properties make polymers useful for making plastic water bottles?
- brittle
- durable ✓
- flexible ✓
- insulator
- lightweight ✓
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- Plastics are polymers, but not all polymers are plastics. Which of the following materials are classified as polymers?
- brass
- carbon fibre
- glass
- rubber ✓
- steel
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- Models are used in science to test ideas without facing practical or ethical issues. However, they have ______, such as only representing one aspect of a concept rather than the whole.
- 'limitations' ✓
- Match the following key terms to their definition.
- atom⇔particles that make up chemical elements ✓
- chemical bond⇔a strong force that holds atoms together in a compound ✓
- chemical compound⇔a substance where two or more different elements are chemically bonded ✓
- element⇔a substance made up of only one type of atom ✓
- molecule⇔made up of two or more atoms chemically bonded (usually non–metals) ✓
- Which of the following properties of rubber makes it useful for making rubber bands?
- brittle
- durable
- flexible ✓
- insulator
- lightweight
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- Consider ice, water, and water vapour. The atoms and molecules are held together differently and with varying strengths. What happens at the boiling point when water turns to water vapour?
- the atoms move around each other in the water molecules
- the chemical bonds in the water molecules become weaker
- the water molecules have enough energy to overcome the forces between them ✓
- the water molecules move around each other more in the liquid
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Exit quiz
- Match the following key terms to their definition.
- chemical bond⇔a strong force that holds atoms together in a compound ✓
- cross–link⇔a chemical bond between atoms in different polymer chains ✓
- forces of attraction⇔a pulling force that keeps particles close together ✓
- plasticiser⇔a substance that is added to a polymer to increase its flexibility ✓
- Materials can be natural or synthetic. Natural means they occur in nature. Synthetic means they are ______.
- 'human-made' ✓
Polymers can be represented with models. Which list correctly describes the image with three polymer models, from left to right?- branched polymer; polymer with plasticiser; cross–linked polymer
- branched polymer; cross–linked polymer; polymer with plasticiser
- cross–linked polymer; polymer with plasticiser; branched polymer ✓
- cross–linked polymer; branched polymer; polymer with plasticiser
- polymer with plasticiser; cross–linked polymer; branched polymer
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- Match the following key terms to their description.
- cellulose⇔natural; carbohydrate found in plant cell walls ✓
- DNA⇔natural; nucleic acid involved in carrying genetic information ✓
- HDPE⇔synthetic; high density poly(ethene) used for plastic bottles ✓
- LDPE⇔synthetic; low density poly(ethene) used for plastic bags ✓
- PVC⇔synthetic; poly(vinyl chloride) used for sockets, switches and wellies ✓
- wool⇔natural; protein fibre often made by sheep ✓
- Cross–links in polymers make it harder for polymer molecules to slide past each other. ______ in between polymer chains push the long molecules apart so that forces of attraction are weakened.
- 'plasticisers' ✓
- A chemical bond is a strong force that holds atoms together in a compound. A chemical bond takes a lot of energy to overcome and break. Which of the following statements are correct?
- In polymers, forces of attraction are the same as chemical bonds.
- In polymers, forces of attraction are weaker than cross–links. ✓
- In polymers, forces of attraction are weakened by plasticisers. ✓
- In polymers, forces of attraction are weakened by branches. ✓
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Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- Polymers are made from small molecules called monomers that join together to form very long chains of atoms.
- Some polymers have high melting points because their molecules are hard to separate.
- Polymers can be made synthetically, but some also exist naturally.
- A plasticiser added to a polymer gets between polymer molecules and allows them to move over each other more easily.
- Cross-links between polymer molecules can make a polymer harder and less flexible.
Common misconception
Students often think that intermolecular forces exist within a molecule, unaware of the significant difference in strength between chemical bonds within atoms and the forces between molecules.
Help students to make the link between the structure of the polymer and its property by using models. Point out where the intermolecular forces occur and compare this to where the chemical bonds are.
Keywords
Polymer - Long-chained molecules formed by joining together monomers.
Forces of attraction - A pulling force that keeps particles close together.
Synthetic - A product that is manufactured from natural resources.
Plasticiser - A substance that is added to a polymer to increase its flexibility.
Cross-link - A chemical bond between different chains of atoms in a polymer.
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