Structure and Bonding

• ionic bonding

  transfer of electrons
• covalent bonding

  sharing of electrons
• metallic bonding

  sea of delocalised electrons
• diamond

  • giant covalent structure
  • each carbon atom forms covalent bonds with 4 other carbon atoms
  • doesn't conduct electricity
  • carbon needs 4 bonds
  • rigid and strong
  • high mp + bp
  • tetrahedral structure
• silicon dioxide

  • bonded to oxygen
• Allotropes of carbon

  • graphite
  • graphene
  • diamond
  • fullerenes
• Graphite

  • each carbon atom forms covalent bonds with three other carbon atoms
  • this forms layers/sheets of hexagonal rings
  • graphite is soft and slippery so it is a good lubricating material
• graphite will have a lower melting point than diamond because of its layers.Weak intermolecular forces between the layers require less energy to overcome than the strong covalent bonds in diamond
• graphite is bale to conduct electricity because each carbon atom has an unbonded electron and is what gives rise to its layers
• graphene

  • single layer of graphite
  • very strong but lightweight
  • conduct electricity due to 1 delocalised electron
  • high melting point as lots of energy is needed to overcome these strong covalent bonds
• fullerens

  • molecules of carbon atoms with hollow shapes
  • structure is based on hexagonal rings of carbon
  • first fullerene to be discovered was buckministerfullerene which has a spherical shape
• carbon nanotubes are cylindrical fullerenes with very high length to diameter ratios
• nanotubes are used to deliver drugs, catalysts, face masks, electrical conductors and wound dressings