allotropes of carbon

• an allotrope is each of different physical forms in which an element can exist
• the allotropes of carbon are diamond, graphite, graphene and fullerene
• all carbon allotropes have giant covalent structures and covalent bonds
• diamond:

  • each carbon atom forms four covalent bonds with other carbon atoms
  • the carbon atoms form a regular tetrahedral network structure
  • no free electrons, cannot conduct
  • hardest natural substance, is very hard
  • very high melting and boiling point
• graphite:

  • each carbon atom forms three covalent bonds with three other atoms
  • forms layers of hexagonal rings, no covalent bonds between the layers
  • weak intermolecular forces between layers, easy to slide
  • has delocalised electrons, fourth electron in outer shell is free
  • is soft
  • used as a lubricant
• graphene:

  • single layer of graphite
  • a layer of interlocking hexagonal rings of carbon atoms
  • one atom thick
  • low density
  • very strong
  • good conductor of thermal energy and electricity
  • has many uses in electronics industry
• fullerenes:

  • hollow shapes
  • hexagonal rings of carbon
• buckminsterfullerene (C60) was the first ever fullerene to be discovered
• carbon nanotubes are cylindrical fullerenes with very high length compared to their diameter, makes them useful for nanotechnology, electronics and materials