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Material Science

Nanomaterials and semiconductors

  • 3 things to know
  • AS 5

Overview

Graphite, graphene and carbon nanotubes, nanotube uses in drug delivery, cancer treatment, biosensors and tissue scaffolds, the risks of nanotechnology, and n-type, p-type and p-n junction silicon.

What you need to know

Answer each one before you reveal it.

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Key term

Describe the structure of graphite.

Key term

What is graphene?

Key term

Describe the structure of a carbon nanotube.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Describe the structure of graphite.

    Model answer

    Graphite consists of layers of carbon atoms arranged in hexagonal rings, each atom bonded covalently to three others. The layers are held together only by weak forces, so they slide easily.

  2. 2

    What is graphene?

    Model answer

    Graphene is a single layer of graphite, one carbon atom thick, with atoms in a hexagonal lattice. Graphene is extremely strong, flexible and a very good electrical conductor.

  3. 3

    Describe the structure of a carbon nanotube.

    Model answer

    A carbon nanotube is a sheet of graphene rolled into a seamless cylinder a few nanometres across. Single-walled nanotubes have one layer, while multi-walled nanotubes have several nested tubes.

  4. 4

    What are the main physical properties of carbon nanotubes?

    Model answer

    Carbon nanotubes have a very high tensile strength and stiffness with a low density. Nanotubes also conduct heat and electricity very well along their length.

  5. 5

    How could carbon nanotubes be used to deliver drugs?

    Model answer

    Drug molecules can be loaded inside the hollow tubes or attached to their large outer surface. Nanotubes linked to targeting molecules could release the drug at diseased cells, reducing side effects.

  6. 6

    How could carbon nanotubes be used to destroy cancer cells selectively?

    Model answer

    Nanotubes attached to antibodies bind to cancer cells. Near-infrared light, which passes through tissue, then heats the nanotubes and kills only the cells they are bound to.

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