Natural Science & Technology: Grade 5
Matter and Materials: Uses of Metals
USES OF METALS
In the last section, we saw that metals have certain properties which make them suitable
materials for many different uses.
These properties were that metals:
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are shiny
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are hard
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are strong
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are malleable
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are ductile
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melt at high temperatures
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are good electrical conductors
Strong Metal Gears
Ductile Wire Fencing
Shiny Metal Surgical Instruments
In addition to the above list, metals have other special properties, which we will learn about
in this section.
We will cover thermal (heat) conductivity and magnetism and see how these properties are
useful for making certain items.
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Natural Science & Technology: Grade 5
Matter and Materials: Uses of Metals
Thermal (Heat) Conductivity
Many metals are good conductors of heat. This means that heat can pass through them easily.
This is a property of metals which helps to cook food.
For example, the heat is transferred from a metal pan to the food when it is heated.
Metal Pan – Conductor
Some metals are better conductors of heat than others. For example, steel, iron and zinc are
not as good at conducting heat as copper and aluminium. Silver is the best conductor.
Magnetism
Magnets have been used for thousands of years, for example in compasses. Magnetic
compasses are used to navigate. Every appliance that you use in the home that has an electric
motor uses magnets to turn electricity into motion, for example, an electric toothbrush, a lawn
mower and a computer’s hard drive.
An Electric Motor Uses Magnets
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Natural Science & Technology: Grade 5
Matter and Materials: Uses of Metals
Certain metals are attracted to magnets. Common metals that are magnetic are:
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iron
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nickel
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cobalt
Other common metals, such as aluminium, copper, gold and silver are non-magnetic.
Non-metals, such as paper, plastic, textiles, wood and glass are also non-magnetic.
Some alloys, which are mixtures of metals and non-metals are also magnetic, for example,
ferrites,which are alloys made of iron. The Earth’s core is an alloy of iron and nickel, so
creates a magnetic field around the Earth.
The Earth’s Core Creates a Magnetic Field
This magnetism property is useful as it helps us to sort metals.
Magnets are made of iron as it is a strong magnet, or steel, which is an alloy that contains a
lot of iron. A magnet only attracts (pulls) metals that are made of iron or contains iron.
The ends of a magnet are called its north and south poles and are where the magnetic pull is
the strongest. The magnetic field is the area around the poles where objects can be pulled
towards the magnet.
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Natural Science & Technology: Grade 5
Matter and Materials: Uses of Metals
Magnet with Iron Filings
If you try to put two magnets together with the same poles pointing towards each other, they
will push away (repel) from each other.
However, if you put the two magnets with different poles pointing towards each other they
will pull together (attract).
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Natural Science & Technology: Grade 5
Matter and Materials: Uses of Metals
Corrosion
Corrosion is the deterioration of a metal when it reacts in a certain environment, for example
when it combines with oxygen. It is a natural process. The most common type of corrosion is
rusting of iron and steel objects.
Rust is formed when iron reacts with oxygen in the air or water (like rain) to form iron oxide
(rust). It changes colour and starts to fall apart.
Rusty Metal Sheet
The rust or iron on objects can be prevented by painting them with special paint. The only
metals that do not rust are precious metals such as gold, silver and platinum, as well as
copper.
Corrosion causes the metal to lose its strength and changes its appearance. It also allows
water to seep through.
Rust is one type of corrosion. Other types of corrosion include:
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Green coating that forms on copper, called copper carbonate or patina.
Copper Carbonate or Patina
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Natural Science & Technology: Grade 5
Matter and Materials: Uses of Metals
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Greyish-white coating that forms on aluminium, called aluminium oxide.
Aluminium Oxide
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Black spots that form on brass.
Black Spots on Brass
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Coating that forms on silver, called tarnish.
Tarnish on Silver
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Natural Science & Technology: Grade 5
Matter and Materials: Uses of Metals
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Dull coating that forms on coins called copper oxide.
Copper Oxide on Coins
Not all metals corrode. For example, stainless steel which is an iron alloy, has metals such as
nickel and chromium added and these form a hard coating that resists attack by oxygen in the
air.
Stainless Steel Pots
Corrosion damages objects and sometimes makes them useless. Corrosion is therefore
expensive and can also be dangerous, for example, if the metal railings or a metal bolt on a
bridge become rusted.
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Natural Science & Technology: Grade 5
Matter and Materials: Uses of Metals
Rusted Metal Bridge
Everyday Uses of Metals
Metals are all around us and we use them every day.
Their properties mean that they can be used to make products such as cars, aeroplanes, coins,
wire, jewellery, bridges, tools and equipment, kitchen utensils, bridges, etc.
Coins
Jewellery
Kitchen Utensils – Pots
Furniture
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Natural Science & Technology: Grade 5
Matter and Materials: Uses of Metals
As metals are good conductors of electricity, metal is used to make wire inside electrical
cables.
Electrical Cable
Metals are malleable and can be made into thin sheets so they can also be used to make
vehicles, such as ships, cars and planes.
Aeroplane
Metals are dense and strong, so they can be used to make objects that support a heavy load,
for example a bridge or a window frame.
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Steel Arch Shaped Bridge
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Natural Science & Technology: Grade 5
Matter and Materials: Uses of Metals
Metals have a high melting point, so they cannot be melted down easily and are therefore
used to make coins.
Coins
Metals are ductile, so they can be made into thin wire without breaking.
Wire
Examples of Metals
An alloy is a mixture of two or more metals. Bronze, brass and stainless steel are alloys.
Stainless Steel
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Natural Science & Technology: Grade 5
Matter and Materials: Uses of Metals
Iron
Long ago, after the use of stone hand tools, people started using iron hand tools. Nowadays,
steel, which is an alloy of iron, is usually used instead. Iron is magnetic and strong.
Plier Jaws Made of Steel
Brass
Brass is an alloy of copper and zinc. It is used mainly to make musical instruments, hinges,
window latches and door handles, as it is attractive and durable.
Brass Trumpet
Steel
Steel is used in many objects, because it is cheap, very strong and easy to shape.
Steel is Strong and Easy to Shape
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Natural Science & Technology: Grade 5
Matter and Materials: Uses of Metals
Stainless steel has less carbon and more chromium in the alloy. It is an alloy made of iron
and nickel. It is resistant to rust and stains and easy to maintain. It is used to make small hand
tools, pans and cutlery.
Stainless Steel Kitchen Utensils
Titanium
Titanium is lighter than steel and is strong and rust-resistant. It can be made into an alloy with
other metals. As an alloy, it is used to make blades, as it is hard and therefore ideal to use for
cutting objects.
Titanium Crystal Bar
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Titanium Products
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Attribution Share-Alike: CSIRO
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