• Metal atoms are tightly packed together in lattice structures
• When the metal atoms are in lattice structures, the electrons in their outer shells are free to move through the structure
• The free-moving electrons are called ‘delocalised electrons’ and they are not bound to their atom
• When the electrons are delocalised, the metal atoms become positively charged
• The positive charges repel each other and keep the neatly arranged lattice in place
• There are very strong electrostatic forces between the positive metal centres and the ‘sea’ of delocalised electrons

The positive metal centres are suspended in a ‘sea’ of delocalised electrons

• The strength of electrostatic 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

Metallic bonding table