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Bonding, structure and properties of materials - OCR 21st CenturyVery large molecules

Different materials can be made from atoms of the same element. The properties of the material depend upon the bonding between the atoms and structure of the substance.

Part of Chemistry (Single Science)Material choices

Very large molecules

Graphene

is an of carbon. Its structure resembles a single layer of . Graphene has a very high and is very strong because of its large regular arrangement of carbon joined by . Like graphite, it electricity well because it has that are free to move across its surface.

Fullerenes

A is a allotrope of carbon. Two examples of fullerenes are and .

Nanotubes

A nanotube resembles a layer of graphene, rolled into a tube shape. Nanotubes have high , so they are strong in and resist being stretched. Like graphene, nanotubes are strong, and they conduct electricity because they have delocalised electrons.

Covalent structure of a nanotube
Figure caption,
Nanotubes can be several millimetres long but only a few nanometres wide

Buckyballs

Buckyballs are spheres or squashed spheres of carbon atoms. They are made up of large molecules so are not classed as . Weak exist between buckyballs. These need little to overcome, so substances consisting of buckyballs are slippery and have lower melting points than graphite or .

Covalent structure of buckminsterfullerene
Figure caption,
Buckminsterfullerene has 60 carbon atoms joined by covalent bonds