Properties of metals

Physical properties

Typical physical properties of metals:

Some metals have properties that are not typical. For example:

  • mercury (a metal) has a low melting point and exists as a liquid at room temperature
  • elements in group 1 have low melting points, but also low densities, for example, sodium is less dense than water and so it floats

A substance with a high density means it has a high mass for its size. For example, the volume of liquid in a can of drink is 330 cm3. If the can was filled with sodium (density = 0.97 g/cm3) then the can would have a mass of around 320 g. However, if the can was filled with lead (density = 11.34 g/cm3), then the can would have a mass of nearly 3.75 kg!

Malleable substances can be bent or hammered into shape without shattering, while brittle substances shatter when bent or hit.

Metals are described as ductile because they can be drawn out into thin wires.

Melting point and boiling point

When a metal melts or boils, this is a change of physical state.

Energy is transferred to a substance to melt or boil it. This energy is needed to overcome the forces of attraction between the metal ions and the delocalised electrons in the metal. The more energy needed, the higher the melting point or boiling point.

As metals are giant lattice structures, the number of electrostatic forces to be broken is extremely large, and so metals have high melting and boiling points. This means that the melting point and boiling point of metals are more similar to those for ionic compounds than for covalent substances.

For example, the table shows this data for magnesium, chlorine and magnesium chloride.

SubstanceFormulaMelts atBoils atBond type
MagnesiumMg650°C1091°CMetallic
ChlorineCl2−101°C−34°CSimple molecular
Magnesium chlorideMgCl2714°C1412°CIonic

Explaining metal properties

Malleability and ductility

The structure of metals consists of layers of metal ions. These layers can slide over each other when a force is applied. This means that the layers of the metal can be hammered flat, and they can also slide over each other to make thin wires.

Metallic bonding allows the metal to change shape without shattering.

Conduction of electricity

Substances conduct electricity because they contain charged particles that are able to move.

When a voltage is applied to a metal, the delocalised electrons travel through the lattice structure. The movement of these charged particles forms an electric current. Notice that the metal ions in the metallic lattice are held in fixed positions and are not able to move.

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