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Aluminium

physical science Maturity 9-11 Next article →

Aluminium is a vital chemical element used in almost every part of modern life. It is identified by the symbol Al and has the atomic number 13. This post-transition metal is a member of the boron group. It is highly valued because of its low density and unique chemical properties. In fact, its density is only about one-third that of steel.

Lingot aluminium
Lingot aluminium

This lightness makes it indispensable for many engineering tasks. It is also highly reflective and visually resembles silver.

Elemental Bullion
Elemental Bullion

The way aluminium interacts with its environment is quite remarkable. The metal has a very strong affinity for oxygen. When the surface of the metal is exposed to air, it reacts with oxygen to form a thin layer of oxide. This layer is approximately 5 nanometers thick at room temperature. This process is known as passivation. The oxide layer acts as a protective shield. It prevents further corrosion from oxygen, water, or even dilute acids.

AlHydrolysis
AlHydrolysis

This makes the metal much more durable than it might otherwise be.

Aluminium possesses several distinct physical characteristics. It is soft, nonmagnetic, and very ductile. Ductility means it can be easily drawn into wires. It is also malleable, allowing it to be shaped or pressed without breaking.

Because it is a metal, it forms a face-centered cubic crystal system. This structure is held together by metallic bonding. While pure aluminium is quite soft, engineers often use aluminium alloys to increase its strength. These alloys can have yield strengths between 200 MPa and 600 MPa. This is much higher than the 7–11 MPa found in pure aluminium.

Aluminium Atomic lattice
Aluminium Atomic lattice

The history of aluminium is a story of scientific breakthroughs. Danish physicist Hans Christian Ørsted announced its discovery in 1825. Later, in 1856, French chemist Henri Étienne Sainte-Claire Deville began the first industrial production. However, aluminium was not widely available until a major change occurred in 1886. This was the development of the Hall–Héroult process. This method was created independently by Paul Héroult in France and Charles Martin Hall in America. This process allowed for mass production, which changed everything for the industry.

In terms of abundance, aluminium is incredibly common. It is the 12th-most abundant element in the entire universe. On Earth, it is the third-most abundant element in the crust, following only oxygen and silicon. It is not found as a free metal in nature. Instead, it is obtained by mining bauxite, which is a sedimentary rock rich in aluminium minerals.

Bauxite hérault
Bauxite hérault

By 1954, aluminium had become the most produced non-ferrous metal, surpassing copper in volume. Today, it is consumed heavily in transportation, construction, and packaging.

Aluminium - world production trend
Aluminium - world production trend

Aluminium also has fascinating properties related to its isotopes. It has one stable isotope, 27Al, which makes up nearly all naturally occurring aluminium. Other isotopes are radioactive. One notable isotope is 26Al, which has a half-life of 717,000 years. Scientists use the ratio of 26Al to 10Be for radiometric dating. This helps them study geological processes like erosion or sediment burial over millions of years.

Aluminium Atomic lattice
Aluminium Atomic lattice

Some scientists even believe the decay of 26Al helped melt asteroids 4.55 billion years ago.

Finally, the metal's utility extends to electrical and thermal systems. It is an excellent conductor of both heat and electricity. In fact, you only need half the weight of copper to match the same amperage. This efficiency is why it is so popular in the aerospace and automotive industries.

Austin A40 Roadster ca 1951
Austin A40 Roadster ca 1951

You can see its impact in everyday items, such as the common soda can.

From massive airplane wings to tiny food packaging, aluminium connects many different scientific fields to our daily lives.

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🖼️ Images & Media (19)
File:Aluminium_Atomic_lattice.png
Aluminium_Atomic_lattice.png
File:Lingot_aluminium.jpg
Lingot_aluminium.jpg
File:Elemental Bullion.jpg
Elemental Bullion.jpg
File:AlHydrolysis.png
AlHydrolysis.png
File:Trimethylaluminium-from-xtal-3D-bs-17-25.png
Trimethylaluminium-from-xtal-3D-bs-17-25.png
File:Bauxite hérault.JPG
Bauxite hérault.JPG
File:Friedrich_W%C3%B6hler_Litho.jpg
Friedrich_W%C3%B6hler_Litho.jpg
File:Eros-piccadilly-circus.jpg
Eros-piccadilly-circus.jpg
File:Lingot aluminium.jpg
Lingot aluminium.jpg
File:Aluminium - world production trend.svg
Aluminium - world production trend.svg
File:The Turner Brass Works ad 1897.jpg
The Turner Brass Works ad 1897.jpg
File:Tovarna glinice in aluminija Kidričevo - kupi aluminija 1968.jpg
Tovarna glinice in aluminija Kidričevo -...

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