Allotropes of Carbon

• Diamond

  In diamond each carbon atom forms four covalent bonds with other carbon atoms, in a giant covalent structure.
• Diamond:

  • is very hard (due to the four other covalent bonds)
  • has a high melting point
  • doesn’t conduct electricity
• Graphite

  In graphite each carbon atom forms three covalent bonds with three other carbon atoms, forming layers of hexagonal rings
• In graphite:

  • there are no covalent bonds between layers (more soft and slippery)
  • one electron from each carbon atom is delocalised
• Graphene

  is a single layer of graphite and has properties that make it useful in electronics (delocalised electrons) and composites (covalent bonds make it strong)
• Fullerenes

  Fullerenes are molecules of carbon atoms with hollow shapes
• Fullerenes

  The structure of them is based on hexagonal rings of carbon atoms but they may also contain rings with 5 or 7 carbon atoms
• Fullerenes

  the first fullerene to be discovered was Buckminsterfullerene (C60) which has a spherical shape
• Carbon nanotubes are:

  • cylindrical fullerenes with
  • high length to diameter ratios
  • useful for nanotechnology, electronics and materials.