Macromolecules

• Diamond:

  • 4 bonds
  • High melting point
  • Doesn't conduct
  • Used for cutting as is strongest known substance

  
• Graphite:

  • Three bonds
  • Made of flat sheets
  • Held together by weak forces so is soft: used as lubricant
  • Conducts electricity as it has one free e

  
• Silicon Dioxide:

  • Makes up sand
  • Each Si is bonded to 4 oxygen atoms, and each oxygen is bonded to 2 silicon atoms
  • it has a high m.p. and is hard, like diamond

  
• Melting point: high - structure made up of strong covalent bonds
• Electrical: don’t conduct electricity - have no mobile ions or electrons, except for graphite