Bonding structure and properties

• Metallic bonding


  When metal atoms bond together
• Metals


  • Have giant structures of regularly arranged atoms
  • The electrons from the outer shells of the atoms are delocalised – meaning they are free to move through the whole structure
  • By sharing delocalised electrons - strong metallic bonds are formed
  • The strength of a metallic bond is due to the force of attraction between the metal ions (+) and the delocalised electrons (-)
• Metallic properties


  • Conduct electricity - the delocalised electrons carry electrical charge through the structure
  • Conduct heat – the delocalised electrons and closely packed ions transfer energy through the structure by conduction
  • Malleable and ductile - The layers of metal ions are able to slide over each other when hammered or stretched
  • High melting and boiling points – large amounts of energy are needed to break the strong metallic bonds in melting / boiling
• Ionic bonding


  The bonding between metal and non-metal atoms
• Ion


  • A charged particle. Has different numbers of protons and electrons
  • Positive ion – has more protons (+) than electrons (-)
  • Negative ion – has more electrons (-) than protons (+)
• Ionic bonding formation


  Ionic bonds form when electrons transfer from a metal to a non-metal atom so that both atoms achieve full outer shells
• Ionic bonding


  • sodium chloride
  • lithium oxide
• Covalent bonding


  The bonding between non-metal atoms
• Covalent bonding formation


  Covalent bonds form when the atoms share electrons so that both atoms achieve full outer shells
• Simple molecular structures


  • Consist of a few atoms held together by covalent bonds
  • Have low melting and boiling points – due to the weak intermolecular forces between the molecules
  • Do not conduct electricity – no free electrons to carry the electric current
• Giant covalent structures


  • Consist of lots of atoms held together by covalent bonds
  • Arranged into giant lattices, which are extremely strong because of the large number of bonds in the structure
• Giant covalent structures


  • Diamond - each carbon bonded to 4 others
  • Graphite - each carbon bonded to 3 others
• Diamond


  • Does not conduct electricity
  • Used in drill bits, glass cutting, gemstones
• Graphite


  • Conducts electricity – delocalised electrons between layers carries charge
  • Used in pencils and lubricants – layers can slide over each other