Aluminium is one of the most versatile metals in modern life. It can be found everywhere: in mobile phones, power lines and high-rise buildings. Aluminium is useful because of its unique properties as a metal. We will explore some of them here.
ALUMINIUM IS LIGHTWEIGHT
Aluminium weighs 3 times less than iron. This low density makes aluminium a useful material to make things that need to be as light as possible, such as boats and airplanes.
ALUMINIUM RESISTS CORROSION
Many metals degrade over time, especially if they are in contact with water or salt. This is called corrosion. Corrosion usually occurs when metals react with oxygen to form metal oxides.
When iron goes brown and rusts, this is what is happening! The iron is reacting with oxygen in the air to form iron oxide, a brown compound we call rust! Rust is not as strong as iron. Over time it crumbles to dust and is blown away!
However, aluminium does not corrode in the same way as other metals. Although aluminium does form a thin aluminium oxide layer, this oxide is still strong. Once the aluminium is covered in this layer, the oxygen cannot get to the aluminium inside, so almost all of the aluminium remains intact!
ALUMINIUM IS A REACTIVE METAL
It reacts quickly with both acids and bases to form hydrogen. Aluminium can also react with iron oxide, which we now know is rust. This reaction gets very hot very quickly and it is used to melt steel in welding! This reaction is called the thermite reaction.
ALUMINIUM IS VERY GOOD FOR MAKING ALLOYS
The reactivity of aluminium means that it can form a wide variety of alloys. Alloys are mixtures of different metals and elements. The exact mix used can greatly affect the alloy’s properties. Aluminium-zinc alloys are used in mobile phones because they are hard but also incredibly light. Meanwhile aluminium-manganese alloys are easy to mould and so are often used to make cooking utensils, which can have unusual shapes.
WHERE DO WE GET ALUMINIUM FROM?
Like all other metals, aluminium is found in the earth. It has been there for millions of years. This means that it has all had time to react, and so a lot of the natural aluminium in the world has corroded into aluminium oxide. The only way to remove the oxygen from aluminium is with the Hall-Heroult Process. This uses electricity to force the aluminium and the oxygen to separate. The difficulty of this process makes aluminium valuable.
The ore we extract aluminium from is called bauxite. Bauxite is a mineral found mainly in tropical regions around the equator beneath clay deposits. It is too impure to use in the Hall-Heroult Process but it can be easily refined. Guinea is Africa’s biggest producer of bauxite, owning 33% of the world’s known reserves. It is estimated that half of the bauxite in the world is still undiscovered.