Metallic Bonding

Metals have a special type of bonding that explains why they conduct electricity and can be bent into shapes. This is called metallic bonding.

What is metallic bonding?

In a metal, atoms lose control of some outer electrons. These electrons become shared and can move freely through the whole structure. The metal atoms become positive ions. The attraction between the positive ions and the moving (delocalised) electrons holds the metal together.

Think of a city of metal ions (like fixed lamp posts) sitting in a sea of free-moving electrons (like people moving between them). The attraction between the lamp posts and the crowd keeps the whole city stable.

$$\text{Metallic bond} = \text{electrostatic attraction between } M^{n+} \text{ and delocalised } e^-$$

Structure: the giant metallic lattice

Metals form a giant lattice: a huge, regular 3D arrangement of positive ions surrounded by a sea of delocalised electrons. It is not made of separate molecules.

Properties explained

• Electrical conductivity: Metals conduct when solid and when molten because delocalised electrons can move and carry charge through the lattice.
• Thermal conductivity: Moving electrons and closely packed ions transfer energy quickly, so metals conduct heat well.
• Malleability and ductility: Layers of ions can slide over each other without breaking the metallic bond, because the attraction is non‑directional (electrons attract ions all around). This lets metals be hammered into sheets (malleable) and drawn into wires (ductile).
• Melting and boiling points: Usually high, because the attraction between ions and electrons is strong and needs a lot of energy to overcome.

Alloys and why they are harder

An alloy is a mixture of a metal with other elements (e.g. brass = copper + zinc; stainless steel = iron with chromium, nickel, and carbon). Different-sized atoms disrupt the regular layers, so layers cannot slide easily. This makes alloys harder and often stronger than pure metals.

Real-world connections

• Copper wires conduct electricity in homes.
• Aluminium foil bends without breaking.
• Stainless steel cutlery is hard and resists rusting.

Common misconceptions

• Metals are not molecules; they are giant lattices.
• Electrons in metals are delocalised; they do not belong to one atom.
• Metals conduct even when solid; ionic compounds do not.