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Key Concepts in Chemistry

Polymers and models of bonding

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Overview

Poly(ethene) as a polymer of ethene with a covalently bonded carbon backbone and chains of varying length, why it is solid, and the limitations of dot and cross diagrams, ball and stick models, two-dimensional drawings and ionic lattice diagrams.

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Key term

What forms the backbone of a poly(ethene) molecule?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What name is given to a very large molecule made by joining many small molecules together?

    Model answer

    It is called a polymer.

  2. 2

    What forms the backbone of a poly(ethene) molecule?

    Model answer

    A long chain of carbon atoms.

  3. 3

    Which small molecule is poly(ethene) made from?

    Model answer

    Ethene.

  4. 4

    What type of bonding holds the atoms together within a poly(ethene) molecule?

    Model answer

    Covalent bonding.

  5. 5

    Poly(ethene) is molecular, yet it is a solid at room temperature. Explain why.

    Model answer

    Its molecules are very large, so the forces between them are strong enough to hold the substance solid.

  6. 6

    Do all the molecules in a sample of poly(ethene) contain the same number of carbon atoms?

    Model answer

    No, the chains vary in length.

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