Properties and uses of metals

Metals are amongst our most valuable resources. Thousands of years ago, people used metals such as Copper and Iron to make weapons and everyday objects. These metals are still in use today.

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Properties of metals

The five most used metals are:

1)Iron

2)Aluminum

3)Copper

4)Zinc

5)Manganese

The general physical properties of metals are:

• They are hard and strong
• They are solids at room temperature (except for Mercury)
• They have a shiny luster when polished.
• They make good conductors of heat.
• They make good conductors of electricity.
• They are dense
• Malleable and Ductile.
• Sonorous

The properties of metals make them suitable for different uses in daily life.

• Copper is a good conductor of electricity and is ductile. Therefore Copper is used for electrical cables.
• Gold and Silver are very malleable, ductile and very unreactive. Gold and silver are used to make intricate jewellery which does not tarnish. Gold can also be used for electrical connections.
• Iron and Steel are both hard and strong. Therefore they are used to construct bridges and buildings. A disadvantage of using Iron is that it tends to rust, whereas Steel does not.
• Aluminum is a good conductor of heat and is malleable. It is used to make saucepans and thin foil, and also aeroplane bodies as it is very light.

Properties of Alloys

  An alloy is a metal mixed with other elements. The properties of an alloy are different from those of pure metals. Some alloys are listed below.

• Steel contains iron and carbon plus other metals. It is stronger than pure iron. It is used as girders for buildings and car bodies.

• Solder is a mixture of tin and lead. It has a lower melting point than pure metals. It is used for connecting electrical circuits.

• Duralumin contains aluminium and copper. It is lighter than copper and stronger than aluminium. It is used in aeroplanes and alloy wheels.

Chemical properties of metals

  Many substances on the Earth's surface will at sometime come in contact with air, water or acids. Therefore the shiny surface of most metals becomes dull in time. This is due to a slow chemical reaction between the surface of the metal and oxygen in the air. The reaction forms only one product; a surface coating of the metal oxide. The general word equation is:

metal+oxygen → metal oxide

For example: The dull appearance of the metal lead is due to a coating of lead oxide.

lead+oxygen → lead oxide

If the surface is scratched then the shiny lead metal can be seen underneath.

Heating can speed up the reaction with oxygen. If a piece of copper is heated it quickly becomes coated in black copper oxide. The word equation is:

copper + oxygen → copper oxide