Aluminium-4
Chunk of aluminium

Aluminium (American spelling: aluminum) is a chemical element. The symbol for aluminium is Al, and its atomic number is 13. Aluminium is the most abundant metal. It is known for its resistance to corrosion and its light weight. Aluminum is used in many industries to manufacture a large variety of products and is very important to the world economy.

Properties

President Lula visit to Aluminum factory
A roll of aluminium

Aluminium is a very good conductor of electricity and heat. It is light and strong. It can be hammered into sheets (malleable) or pulled out into wires (ductile). It is a highly reactive metal, although it is corrosion resistant.

Aluminium prevents corrosion by forming a small, thin layer of aluminium oxide on its surface. This layer protects the metal by preventing oxygen from reaching it. Corrosion can not occur without oxygen. Because of this thin layer, the reactivity of aluminium is not seen.

How was it discovered?

Sometimes there can be disagreement about who discovered something, even when all the facts are known. Friedrich Wöhler is credited with isolating aluminum in 1827 by mixing anhydrous aluminum chloride with potassium. The metal, however, had indeed been produced for the first time two years earlier — but in an impure form — by the Danish physicist and chemist Hans Christian Ørsted. Therefore, Ørsted can also be listed as the discoverer of the metal.

Where did its name come from?

In 1807, Sir Humphry Davy was trying to isolate aluminum from a mineral called alumina. He first called the metal alumium, but decided to call it aluminum in 1812.

Did You Know?

  • Recycling aluminum requires one twentieth as much energy as producing aluminum from raw ore.
  • Aluminum is the most common metal in the earth's crust.
  • Aluminum and Aluminium are two different names for this metal.

Where is it found?

Bauxite
Bauxite, aluminium ore

Aluminum is the most abundant metal in the Earth's crust, and the third most abundant element overall, after oxygen and silicon. But it is not found free in nature. The Bayer process is used to refine aluminum from bauxite, a kind of rock that has aluminium oxide and many impurities

Aluminium was once considered a precious metal that was even more valuable than gold. This is no longer true because, as technology improved, it became cheaper and easier to make pure metal.

What are its uses?

Air.france.b747.2003.750pix
147,000 pounds of aluminum are used in building a single Boeing 747 airplane.

Many things are made of aluminum. Much of it is used in overhead power lines. It is also widely used in window frames and aircraft bodies. It is found at home as saucepans, soft drink cans, and cooking foil. Aluminium is also used to coat car headlamps and compact discs.

Pure aluminium is very soft, so a harder metal is almost always added. The harder metal is usually copper. Copper/aluminium alloys are used to make ships, because the aluminium prevents corrosion, and the copper prevents barnacles.

Aluminium compounds are used in deodorants, water processing plants, food additives, and antacids. Aluminum helps us get from place to place since it's a part of cars, trucks, airplanes, bicycles, rockets, and more.

Every morning you wake up and look in a mirror, the reflective backing is likely made from aluminum. The pots and pans your family uses to cook dinner may be made with aluminum. The utensils you eat your dinner with could be made with aluminum, along with the kitchen aluminum foil used to wrap up leftover food. Soda cans are also made from aluminum.

When aluminum is combined with Fe2O3 in the right quantity thermite can be made. Thermite burns very quickly and with extreme heat. Aluminum is one of the primary components of the fuel that propels rockets into space.

Is it dangerous?

Aluminum isn't dangerous. The metal is protected by a surface layer of aluminum oxide. This surface layer forms at once when the metal is exposed to air, and is very stable. So dishes, pots, and pans can be made of aluminum, and aluminum foil can be used for packing sensitive foods. However, acidic foods, such as tomatoes, can dissolve the surface oxide layer and some of the aluminum underneath. This isn't dangerous and doesn't compromise the strength of the aluminum object, but can lead to off tastes in the food, which is why it is usually not recommended to cook acidic foods in aluminum cookware.

Aluminium is not used in the human body, although it is very common. People debate whether its use in deodorants and water treatment is healthy. Aluminium ions slow down plant growth in acidic soils. Aluminium may be a factor in Alzheimer's disease (a disease when the brain stops working and the patient is confused). But the Alzheimer's Society says overwhelming medical and scientific opinion is that studies have not convincingly demonstrated a causal relationship between aluminium and Alzheimer's disease.

Recycling

Pressed-cans
Aluminium cans ready for recycling at Central European Waste Management's plant in Europe

Since aluminium needs to be made by electrolysis, it requires a very large amount of electrical power. Recycling aluminium would be much cheaper. That's why recycling plants were opened. The cost of recycling aluminium is much less than the cost of making it from bauxite.

Related pages

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Aluminium for Kids. Kiddle Encyclopedia.