Quick Notes Metallic Bonding

  • In metallic bonding, positive metal ions are attracted to negatively charged delocalised electrons, forming a dense and rigid structure.
  • Positively charged metal ions form because metal atoms are more stable if they lose electrons to have a full outer shell.
    • Electrons lost by metal atoms in solid metals have nowhere to go and stay attracted to the positive charge of the metal ions.
    • Electrons are not held by the metal atom but are free to move – they are delocalised.
    • Free movement of delocalised electrons enable metals to conduct electricity.

Full Notes Metallic Bonding

It is seems obvious, but when talking about metallic bonding, we are talking about a specific type of atomic bonding that only occurs in metals.

Metals easily form positive ions. They are more stable with a full outer shell, even if it means they have to have a positive charge.

oxidation of sodium to form positive sodium ion metallic bonding

In metallic bonding, metal atoms ‘lose’ electrons to become positive ions. The electrons ‘lost’ by the metal atoms have nowhere to go. Now ‘free’ they are attracted to the positive charge of the metal ions, but they are not physically held in one place; they are described as being delocalised.

To pass a current through a metal, delocalised electrons are forced to move in a particular direction, (whilst constantly bumping into each other). This is why metals are able to conduct electricity – because they have delocalised electrons in their structures that are able to move.

metallic bonding structure showing positively charged metal ions and delocalised electrons

Metallic bonding is very strong, which is why metals have high melting points and are used for strength in applications.

The greater the charge of the metal ion, the stronger the metallic bonding. In aluminium, for example, each aluminium atom forms an Al3+ ion. Even though each aluminium ion has a low mass (Al has an Ar of 27), the attraction between the 3+ ions and the delocalised electrons is very strong, giving aluminium a very high strength to weight ratio.