Diamond & Graphite

• An allotrope is a different structural form of the same element in the same physical state
• Diamond, Graphite and Fullerenes are allotropes of carbon
• Diamond and Graphite are both:

  • Giant Covalent structures
  • regular lattice of covalently bonded atoms
  • very strong
• Diamond

  • Each carbon atom is covalently bonded to 4 other carbon atoms
  • Very strong
  • High melting point
  • Forms a regular 3D pattern
  • Doesn't conduct electricity as no free electrons or ions
• Graphite

  • Each carbon is bonded to 3 other carbon atoms
  • This means each carbon atom has one spare electron that becomes delocalised, so graphite can conduct electricity and heat
  • Arranged into hexagons that form large flat sheets and then lots of layers
  • The layers are only held together weakly as there are no covalent bonds between them
  • Free to slide over one another, so graphite is soft compared to diamond.
  • Still a high melting point.