Graphene and fullerenes

Graphene and fullerenes are forms of carbon. Their structures are different from those of diamond and graphite, which are also forms of carbon.

Graphene

Graphene is a single layer of graphite. The strong covalent bonds between the carbon atoms mean that graphene:

Like graphite, graphene conducts electricity well because it has delocalised electrons that are free to move across its surface.

These properties make graphene useful in electronics and for making composites.

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Graphene has a giant covalent structure, but fullerenes have large molecules.

Fullerenes

Fullerenes are molecules of carbon atoms with hollow shapes. Their structures are based on hexagonal rings of carbon atoms joined by covalent bonds. Some fullerenes include rings with five or seven carbon atoms. Two examples of fullerenes are buckminsterfullerene and nanotubes.

Buckminsterfullerene

Buckminsterfullerene was the first fullerene to be discovered. Its molecules are made up of 60 carbon atoms joined together by strong covalent bonds. Molecules of C60 are spherical.

There are weak intermolecular forces between molecules of buckminsterfullerene. These need little energy to overcome, so buckminsterfullerene is slippery and has a low melting point.

Covalent structure of buckminsterfullereneBuckminsterfullerene has sixty carbon atoms joined by covalent bonds

Nanotubes

A nanotube is like a layer of graphene, rolled into a cylinder. The length of a nanotube is very long compared to its width, so nanotubes have high length to diameter ratios.

Nanotubes have high tensile strength, so they are strong in tension and resist being stretched. Like graphene, nanotubes are strong and conduct electricity because they have delocalised electrons.

These properties make nanotubes useful for nanotechnology, electronics and specialised materials.

Covalent structure of a nanotubeNanotubes can be several millimetres long but only a few nanometres wide