Properties

• Covalent bonding


  Can be responsible for substances that have many different structures and therefore different physical properties
• Small molecules (e.g. H2O, N2)


  • Simple units made from covalently bonded atoms
  • Contain fixed numbers of atoms
• Giant covalent structures


  • Have a huge number of non-metal atoms bonded to other non-metal atoms via strong covalent bonds
  • Can also be called giant lattices
  • Have a fixed ratio of atoms in the overall structure
• Common macromolecules


  • Diamond
  • Graphite
  • Silicon dioxide
• Giant covalent structures can also be called macromolecules
• Properties of giant covalent substances


  • High melting and boiling points due to many strong covalent bonds
  • Large amounts of heat energy needed to overcome forces and break down bonds
  • Most cannot conduct electricity as they do not have free electrons nor charged particles (but there are some exceptions such as graphite and graphene)
• Examples of carbon-based giant covalent structures


  • Diamond
  • Graphite
  • Buckminsterfullerene
  • Graphene