allotropes of carbon

• diamond

  • each carbon atom is joined to four other carbon atoms by strong covalent bonds
  • the carbon atoms form a regular tetrahedral network structure
  • there are no free electrons
• uses of diamond

  • rigid network of carbon atoms, held together by strong covalent bonds, makes diamond very hard
  • makes it useful for cutting tools, such as diamond-tipped glass cutters and oil rig drills
  • like silica, diamond has a very high melting point
  • it does not conduct electricity
• graphite

  • each carbon atom forms three covalent bonds with other carbon atoms
  • the carbon atoms form layers of hexagonal rings
  • there are no covalent bonds between the layers
  • there is one delocalised electron from each atom
• uses of graphite

  • graphite has delocalised electrons - these electrons are free to move between the layers in graphite, so graphite can conduct electricity
  • this makes graphite useful for electrodes in batteries and for electrolysis
  • the forces between the layers in graphite are weak
  • this means that the layers can slide over each other
  • this makes graphite slippery, so it is useful as a lubricant
• graphene

  • graphene is a single layer of graphite - strong covalent bonds between the carbon atoms mean that graphene:
  • has a very high melting point
  • is very strong
• uses of graphene

  • graphene conducts electricity because it has delocalised electrons that are free to move
  • these properties make graphene useful in electronics and for making composites
• fullerenes

  • fullerenes are molecules of carbon atoms with hollow shapes
  • structures are 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
• buckministerfullerene

  • first fullerene to be discovered
  • 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
• nanotubes

  • 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
  • nanotubes are strong and conduct electricity because they have delocalised electrons
  • these properties make nanotubes useful for nanotechnology, electronics and specialised materials
• uses of fullerenes

  • can be used to cage other molecules to deliver drug into body
  • large surface area - make good catalysts
  • make good lubricants