1.4.9 Properties of Metallic Substances

• Metals form giant metallic lattices in which the metal ions are surrounded by a ‘sea’ of delocalised electrons
• The metal ions are often packed in hexagonal layers or in a cubic arrangement
• This layered structure with the delocalised electrons gives a metal its key properties

Layers of copper ions (the delocalised electrons are not shown in the diagram)

• If other atoms are added to the metal structure, such as carbon atoms, this creates an alloy
• Alloys are much stronger than pure metals, because the other atoms stop the layers of metal ions sliding over each other easily

• The strength of the metallic attraction can be increased by:
  • Increasing the number of delocalised electrons per metal atom
  • Increasing the positive charges on the metal centres in the lattice
  • Decreasing the size of the metal ions

• Due to the delocalised ‘sea’ of electrons, metallic structures have some characteristic properties shown below:

Metallic Bonding Properties Table