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Antimony

physical science Maturity 11-13 Next article →

Antimony is a chemical element with the symbol Sb and the atomic number 51. It is classified as a metalloid, which means it has properties of both metals and non-metals.

Antimony massive
Antimony massive

As a member of group 15 on the periodic table, it is also known as a pnictogen. Antimony is a silvery, lustrous grey solid that remains stable in air at room temperature. It is a relatively rare element in the Earth's crust, where its abundance is estimated at 0.2 parts per million. This makes it the 63rd most abundant element in the crust, appearing in more than 100 different mineral species.

Stibnite
Stibnite

Most antimony is found in the form of a sulfide mineral called stibnite. To extract the pure metal from this ore, industry uses specific chemical processes. One common method involves roasting the stibnite and then performing a reduction with carbon. Another method is the direct reduction of stibnite using iron.

World Antimony Production 2010
World Antimony Production 2010

Once the metal is refined, it is often used to create alloys. An alloy is a mixture of two or more elements. Antimony is frequently combined with lead and tin. These mixtures improve the properties of bullets, solders, and plain bearings. It is also added to lead-acid batteries to increase the rigidity of the lead-alloy plates.

Antimony has a very specific atomic structure that dictates how it behaves. The stable form of the element crystallizes in a trigonal cell. Its elemental structure is layered, consisting of fused, ruffled, six-membered rings.

SbAs lattice
SbAs lattice

This close packing gives antimony a high density of 6.697 g/cm3. However, the bonding between these layers is quite weak. This weak connection is why antimony is characterized by low hardness and high brittleness. On the Mohs scale, it has a hardness of only 3. If you rub the metal with a pestle in a mortar, it can even cause a strong detonation.

Antimony massive
Antimony massive

Different forms, or allotropes, of antimony can exist under certain conditions. The most common is the stable grey form found at room temperature. However, a yellow allotrope can form if stibine is oxidized with oxygen at −90 °C. In ambient light and temperature, this yellow form transforms into the more stable black allotrope.

Antimony massive
Antimony massive

While rare, an explosive form can be created through the electrolysis of antimony trichloride. This form is not considered a true antimony allotrope because it contains significant amounts of chlorine. Scientists also study its isotopes, including two stable ones. One isotope makes up 57.21% of natural antimony, while the other makes up 42.79%.

Human history with antimony stretches back to ancient times. As early as 3100 BC, predynastic Egyptians used antimony sulfide as a cosmetic called kohl.

antimony symbol
antimony symbol

The Roman scholar Pliny the Elder wrote about preparing antimony sulfide for medicine in 77 AD. He even distinguished between "male" and "female" forms of the substance. In 1540, the Italian metallurgist Vannoccio Biringuccio described how to isolate the element.

Specola, medaglione di vannoccio biringucci
Specola, medaglione di vannoccio biringucci

It was not until 1783 that a Swedish scientist described the first discovery of naturally occurring pure antimony in the Earth's crust. This was found at the Sala Silver Mine in the Bergslagen mining district.

In the modern world, antimony is vital for technology and safety. China is currently the world's largest producer of antimony and its compounds. Much of this production comes from the Xikuangshan Mine in Hunan.

World Antimony Production 2010
World Antimony Production 2010

One of its most important uses is as an additive in flame retardants. Specifically, antimony trioxide is added to halogen-containing materials to help prevent fires. Antimony is also used in the electronics industry as a dopant. A dopant is a substance added to a semiconductor to change its electrical properties.

InSb IR detector
InSb IR detector

This makes it essential for the production of various semiconductor devices.

Antimony's chemistry is quite diverse, involving many different compounds. It can form oxides, such as antimony trioxide, which is produced when the metal is burnt in air. It can also form halides, which are compounds containing fluorine, chlorine, bromine, or iodine. For example, antimony pentafluoride is a powerful Lewis acid.

Antimony-pentafluoride-monomer-3D-balls
Antimony-pentafluoride-monomer-3D-balls

This means it is very good at accepting electron pairs from other molecules. The element also forms organoantimony compounds, which are created through the alkylation of antimony halides. These complex chemical relationships allow antimony to play a role in everything from heavy industrial manufacturing to tiny, high-tech computer components.

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🖼️ Images & Media (10)
File:Antimon.PNG
Antimon.PNG
File:Antimony massive.jpg
Antimony massive.jpg
File:SbAs lattice.png
SbAs lattice.png
File:Stibnite.jpg
Stibnite.jpg
File:Antimony-pentafluoride-monomer-3D-balls.png
Antimony-pentafluoride-monomer-3D-balls.png
File:antimony symbol.svg
antimony symbol.svg
File:Specola, medaglione di vannoccio biringucci.JPG
Specola, medaglione di vannoccio biringucci.JPG
File:World Antimony Production 2010.svg
World Antimony Production 2010.svg
File:Antimony - world production trend.svg
Antimony - world production trend.svg
File:InSb IR detector.jpg
InSb IR detector.jpg
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