Science

Metal properties

The way that metal atoms are arranged to make a crystal lattice gives metals particular properties. The uses we make of metals depend on these properties.

Metal properties and uses

Most metals are very strong. They have high melting points and they have high heat and electrical conductivity. They are also malleable, which means they can be beaten or pressed into thin sheets.

Compare the melting and boiling points of the metals and non-metals in this table:

Melting and boiling points of metals and non-metals

ElementMetal or non-metalMelting point / °CBoiling point / °C
aluminiummetal6612,467
goldmetal1,0642,807
ironmetal1,5352,750
tungstenmetal3,4075,927
iodinenon-metal114185
phosphorusnon-metal44280
sulfurnon-metal113445

The uses we make of metals are related to their properties:

  • Car bodies are made from steel, which is mostly iron, because it is a very strong material that is easy to press into the required shape.

  • Electrical wiring is made from copper because it is a very good conductor of electricity.

  • The filament of a light bulb is made from tungsten because this metal does not melt at the very high temperature needed to make it white hot.

Metals have their characteristic properties because of their giant structure. In a metal crystal, the atoms are in a regular arrangement and strongly bonded together. Strong metallic bonding makes metals hard, but allows layers of atoms to slide so that the metal is malleable. The layers of atoms also allow an electric current to pass through.

The extensive use of metals is having an effect on our environment:

  • Strip mining of metal ores creates large areas of barren and lifeless land.

  • Waste material from metal extraction is left in spoil tips that scar the landscape.

  • While some used metals are recycled, many metal articles are simply dumped.

  • Toxic metal compounds leach out of waste material to pollute the environment, killing wildlife.

Read on if you are taking the Higher paper.

Metal structure - Higher

We can explain the properties of metals by taking a more detailed look at their structure. Metal crystals are made up of positive metal ions surrounded by a sea of negative electrons.

showing free electrons from the outer electron shells mingled with positively charged metal ions

Atomic structure of a metal

The strong electrostatic attraction between positive ions and negative electrons means that a lot of energy is needed to separate these particles from the crystal lattice. This means that metals are strong and have high melting and boiling points.

Much less energy is needed to slide one layer of positive metal ions over another layer. This means that metals are easy to beat or press into shape.

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

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