Coaching Centre
Elements in the modern world
How we extract and use metals today, including electrolysis of copper and aluminium, steel and sulfuric acid, the elements inside a smartphone, Australia's critical minerals, and why recycling matters when resources are limited.
In the 1850s, aluminium was so hard to extract that it was more precious than gold. The French emperor Napoleon III is said to have served his most honoured guests with aluminium cutlery, while lesser guests made do with gold. Today aluminium is so cheap we wrap sandwiches in it.
Extracting metals with electricity
Very reactive metals hold on to the other elements in their ores so tightly that charcoal and heat can't pull them out. Instead we use electrolysis: passing an electric current through a melted or dissolved compound to split it into simpler substances.
In 1886 Charles Hall in the USA and Paul Héroult in France independently discovered how to extract aluminium cheaply by electrolysis, and its price crashed. Aluminium is light, strong when alloyed and protected by its oxide layer, so it is used in planes, cars, boats, window frames and drink cans. Its ore, bauxite, is mined in huge amounts in Australia, the world's largest producer. Electrolysis uses enormous amounts of electricity: recycling an aluminium can takes only about 5% of the energy needed to make a new one from bauxite.
Copper is also purified by electrolysis, and the same process is used for electroplating: coating an object with a thin layer of metal, such as chrome on taps or gold on electrical contacts.
Iron, steel and sulfuric acid
Steel is the most used metal material in the world: around 1.9 billion tonnes are made each year, for buildings, bridges, cars, ships, tools and cans. Its main drawback is that it rusts. Australia is the world's biggest exporter of iron ore, mostly from the Pilbara region of Western Australia.
Sulfuric acid (H2SO4) is produced in larger amounts than any other industrial chemical. More than half of it is used to make fertilisers, which help grow food for billions of people. The rest goes into making detergents, paints and pigments, plastics, medicines, car batteries and metals. It is used for its chemical properties: it is a strong acid that reacts with many substances.
What's in your phone?
A smartphone contains more than 30 different elements, each chosen for its properties.
- Indium tin oxide forms an invisible conducting layer on the touchscreen, which detects your finger.
- Silicon is the semiconductor in the chips; tiny gold and copper wires connect them because they conduct well and don't corrode.
- Lithium and cobalt are in the rechargeable battery. Lithium is the lightest metal, so batteries can store a lot of energy for their weight.
- Neodymium, a rare earth element, makes tiny but very strong magnets for the speakers and the vibration motor.
- Aluminium (or steel or titanium) forms a light, strong case.
Limited resources
Ores are non-renewable: once mined, they're gone, and the richest ores are used first. Some elements needed for phones, electric cars, wind turbines and solar panels are scarce or come from only a few places. Governments call them critical minerals. Australia has large deposits of many of them and is the world's largest producer of lithium, mainly from Western Australia.
Recycling helps. Metals can be melted down and reused again and again without losing their properties. A tonne of old phones contains far more gold than a tonne of gold ore. Yet Australians throw out about 20 kg of electronic waste per person each year, and much of it is never recycled. Phones and batteries should go to an e-waste drop-off point, never in the household bin.
Test yourself
Aluminium is extracted from bauxite using
Aluminium is too reactive to extract with carbon.
In the electrolysis of copper sulfate, copper forms on
Positive copper particles are attracted to the negative electrode.
Most sulfuric acid is used to make
More than half goes into fertilisers.
Which element in a phone is used mainly for its magnetic properties?
Neodymium magnets are small but strong.
Recycling an aluminium can saves energy because
About 5% of the energy.
Lithium is used in phone batteries mainly because it
Light weight matters in portable devices.
Label the elements inside the phone.
Label the electrolysis set-up.
Using electricity to split a compound is called . The ore of aluminium is . Coating an object with a thin layer of metal is called . Ores are resources. Elements that are important but in short supply are called minerals.
Explain why recycling old mobile phones is important. Refer to the properties of metals, limited resources and energy use.
Mobile phones contain more than 30 elements, including gold, copper, lithium, cobalt and rare earth elements such as neodymium. These come from ores, which are non-renewable: once they are mined they can't be replaced, and some are scarce or come from only a few countries. Metals keep their properties when they are melted down, so the metals in old phones can be recovered and used again and again.
Recycling also saves energy. Extracting metals from ore takes huge amounts of energy, especially reactive metals that need electrolysis, so recovering metal from old devices uses far less energy and causes less mining damage. Recycling also keeps lithium batteries out of rubbish trucks and landfill, where they can catch fire or leak toxic substances.