4.4 Metallic bonding

Define metallic bond.

The electrostatic attraction between positive metal ions and delocalised electrons.

What is meant by delocalised electrons?

Electrons that are not bound to a single atom and can move freely through the metal lattice.

What is a metallic lattice?

A structure of closely packed metal cations surrounded by a sea of delocalised electrons.

Why do metals conduct electricity?

Delocalised electrons can move freely and carry charge.

Why are metals malleable and ductile?

Layers of ions can slide over each other without breaking the metallic bond.

What affects the strength of metallic bonding?

Number of delocalised electrons and charge density of metal ions.

Why do metals have high melting points?

Strong attraction between cations and delocalised electrons requires large amounts of energy to overcome.

What is an alloy?

A mixture of metals, or a metal and another element, with improved mechanical properties.

Why do alloys tend to be harder than pure metals?

Different-sized atoms disrupt the lattice, preventing layers from sliding easily.

What is charge density?

The ratio of ion charge to ionic radius; higher charge density → stronger metallic bonding.