metallic bonding

• metals have the physical properties

  • high melting temperature
  • good electrical conductivity
  • good thermal conductivity
  • malleability
  • ductility
• the electrical conductivity of a metal generally increases as the number of outer-electrons increases
• metallic bonding is the electrostatic force of attraction between the nuclei of a cation and the delocalised electrons
• the number of delocalised electrons per cation played a part in determining the melting temperature of the metal

  • group 1 metals have low melting temperatures
  • group 2 have higher melting temperatures
• metals in the d block typically have high melting temperatures as they have more delocalised electrons per ions
• the smaller a cation the closer the delocalised electrons are to the central nucleus and so the greater the electrostatic force if attraction
• when a potential difference is applied across the end of a metal the delocalised electrons will be attracted o and move towards the positive terminal o the cell this movement of electric charge constitute an electric current
• two factors contribute to the ability of metals to transfer heat energy

  1. the free moving delocalised electrons to pass kinetic energy along the metal
  2. the cations are closely packed and pass kinetic energy from one to another
• metal can be pressed or hammered into different shapes this is malleability
• they can also be drawn into wires this is ductility
• when stress is applied to a metal the layers of cations may slide offer one another and as the delocalised electron are free moving they move with the cations and prevent strong forces of repulsion from forming between the cations in one layer and the cations in another layer
• delocalised electrons = electrons that are not associated with any single atom or any single covalent bond
• metallic bonding is the electrostatic force of attraction between the nuclei of a metal cation and the delocalised electrons