Allotropes of Carbon

• Diamond:

  • Diamond is formed in very rigid covalent structure
  • Diamond is made of carbon atoms that each form 4 covalent bonds - this makes diamond very hard
  • Diamond has high melting point as it has strong covalent bonds
  • It has no free electrons so it doesn't conduct electricity
• Graphite:

  • Each carbon atom forms 3 covalent bonds
  • Graphite is formed in sheets of carbon atoms arranged in hexagons
  • They have no covalent bonds between layers and are held together weakly - free to move over each other
  • This makes graphite soft - good for lubrication
  • Graphite has high melting point
  • Only 3 carbon atoms out of 4 in outer shell are used in bonds, so each carbon atom has one delocalised electron - graphite conducts electricity
• Graphene:

  • Graphene is one singular sheet of carbon atoms joined by hexagons - sheet of atoms in one atom thick
  • Graphene is very strong
  • Graphene is very light - can be used to improve strength of composite materials without adding much weight
  • Graphene has delocalised electrons so they can conduct electricity
• Fullerenes:

  • Fullerenes are molecules of carbon shaped like closed tubes
  • Fullerenes can be used to cage other molecules - can be used to deliver drug into body
  • Fullerenes have large surface area - make good industrial catalysts and lubricantes
• Fullerenes (Nanotubes):

  • Fullerenes can form nanotubes - tiny carbon cylinders
  • Nanotubes can conduct electricity
  • Have high tensile strength (don't break when stretched)
  • Are used in electronics and to strengthen materials