Metallic bonding

A more complex model is needed to explain the bonding in metals.

This model represents metal crystals as being made up of positive metal ions surrounded by a sea of negative electrons. The electrostatic attraction between these opposite charges creates the metallic bonds. The force of this attraction is very strong.

Delocalised electrons moving freely among an array of tightly packed metal atoms.

The sea of electrons is mobile. If a potential difference is applied across a piece of metal, the electrons will move, carrying an electrical current. This is why metals are good conductors of electricity.

Explaining properties of metals

The giant structure of metals and metallic bonding explain their properties.

PropertyExplanation
Strong high melting pointA large amount of energy is needed to overcome the large number of strong metallic bonds
HardnessMetallic bonds are very strong so the giant metallic structure is strongly held together
Malleable (can be shaped); ductile (can be drawn into thin sheets or wires) Layers of metal ions can slide over each other when forces are applied
Good conductors of heat and electricityElectrons in the 'sea' of electrons are free to move
Question

Why are group 1 metals soft and why do they have low melting points?

They have weaker metallic bonds than other metals. Less energy is needed to overcome these bonds than in other metals.

Move on to Test
next