Metallic Bonding

Full Notes

Metallic bonding has been outlined with more background theory and detail at this page.
This page is just what you need to know for CIE A-level Chemistry :)

Definition of Metallic Bonding

Metallic bonding is the strong electrostatic attraction between positive metal ions (cations) and a sea of delocalised electrons.

Metal atoms form positive ions easily because their outer electrons are weakly attracted to the nucleus.

These electrons can drift away, becoming delocalised and forming a ‘sea’ of negative charge. The resulting positive metal ions are strongly attracted to this sea of delocalised electrons. This electrostatic attraction holds the structure together in a rigid, fixed arrangement.

Example Structure of Sodium (Na)

• Each sodium atom loses one outer electron*, forming Na⁺ ions.
• The lost electrons become delocalised, forming an electron cloud.

There is strong attraction between Na⁺ ions and the delocalised electrons, which holds the metal together.

Properties of Metals Explained by Metallic Bonding

High Melting and Boiling Points

Strong electrostatic forces between positive ions and delocalised electrons require a large amount of energy to break.

Electrical and Thermal Conductivity

• Metals conduct electricity in both solid and molten states.
• The delocalised electrons are free to move, allowing them to carry charge or heat energy.
Example Copper (Cu) is used in electrical wiring due to its high conductivity.

Malleability and Ductility

• Malleability: Metals can be hammered into shapes.
• Ductility: Metals can be drawn into wires.
• Metal ions are arranged in layers that can slide over each other without breaking up the attraction between ions and delocalised electrons.
Example Gold (Au) is highly malleable and used for jewellery.

Summary

• Metallic bonding is the attraction between positive metal ions and delocalised electrons.
• Metals form cations easily as outer electrons are weakly held.
• Delocalised electrons form a ‘sea’ that strongly attracts the cations, holding the structure together.
• Properties explained by metallic bonding:
  • High melting/boiling points due to strong forces.
  • Conduct electricity and heat due to mobile delocalised electrons.
  • Malleable and ductile because layers of ions can slide while attraction remains intact.