Metallic bonding

• The 3-D crystal lattice of metals consist of positive ions, NOT atoms surrounded by a 'sea of electrons' forming another type of giant lattice.
• In metallic bonding, the outer electrons(-), from the original metal atoms are free to move around between the positive metal aooms formed(+)

  These free or 'delocalised' electrons are the 'electronic glue' holding the particles together.

  There is a strong electronic force of attraction between these mobile delocalised electrons(-) and the 'immobile' positive metal ions(+) and this is the metallic bond.
• Physical properties of metals:

  1. Metals are good conductors of electricity because these 'free' delocalised electrons can move and carry charge
  2. The strong metallic bonding generally results in dense, strong materials with high melting and boiling points. A huge amount of energy is needed to break all the bonds(attraction between the positive ions and delocalised electrons) in order to melt a metal
  3. Metals are very malleable and ductile. Malleable - The metal can be readily bent, pressed or hammered into shape. Ductile - The metal can be stretched into a wire.
• In metallic bonding, the layers can slide over each other without fracturing the structure. The electrons still attract the positive ions(no matter which ones they are) and the metallic bonding is not disrupted.
• An alloy is a mixture of two or more elements, at least one of which is a metal, and that the resulting mixture has metallic properties.
• All metals, except for mercury, are solid at room temperature.
• Most metals have very high melting or boiling points.
• Metals have very good electrical conductivity
• A nanoparticle is a structure that is 1-100nm in sized and contains a few hundred atoms. They have very different properties and uses from bulk material(meaning powders and lumps). This is due to their high surface area to volume ratio