Metallic Bonding (WJEC GCSE Chemistry: Combined Science)

The Structure of a Metal

• Metals consist of giant structures
• Within the metal lattice, the atoms lose their outer electrons and become positively charged metal ions
  • The outer electrons no longer belong to any specific metal atom and are said to be delocalised
  • This means they can move freely between the positive metal ions and act like a “sea of electrons”
• The metallic bond is the strong force of attraction between the positive metal ions and the delocalised electrons
• This type of bonding occurs in metals and metal alloys, which are mixtures of metal

Diagram to show metallic bonding

There is attraction between positive metal ions and delocalised electrons

Linking the Bonding & Properties

• Most metals have high melting and boiling points 
  • There are strong electrostatic forces of attraction between the positive metal ions and the negative delocalised electrons within the metal lattice structure
  • These needs lots o energy to be broken 
• Metals are good conductors of heat and electricity 
  • The delocalised electrons are free to move and carry a charge through the whole structure 
• Most metals are malleable
  • This means they can be hammered into shape
  • This is because the atoms are arranged in layers which can slide over each when force is applied 

Malleability of metals 

When a force is applied, the layers of positive ions slide over each other

Higher Tier

• The melting point increases going across a period (row) in the Periodic Table 
  • For example, the melting point increases going from sodium to magnesium to aluminium 
• This is because the number of delocalised electrons increases 
• Therefore, there are greater forces of attraction between the positive ions and delocalised electrons
  • So, more energy is required to overcome this attraction resulting in a higher melting point