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Bismuth

physical science Maturity 7-9 Next article →

Bismuth is a very special metal with the symbol Bi. It has the atomic number 83 on the periodic table.

Bismuth symbol
Bismuth symbol

This metal is a post-transition metal. It is part of a group called pnictogens. This group also includes arsenic and antimony. Bismuth is quite heavy. It is about 86% as dense as lead.

BrokenBismuthIngot
BrokenBismuthIngot

One amazing thing about it is how it reacts to light. When it is freshly made, it looks silvery-white. However, a thin layer forms on the surface. This layer usually gives the metal a rosy color. If you heat it, the metal can show many colors. This rainbow effect is called iridescence. It happens because of thin-film interference. This is when light waves bounce off the surface in a special way.

Bismuth has some very unusual physical traits. It is a brittle metal. This means it can snap or break easily. It is also the most diamagnetic element known. This means it is pushed away by magnetic fields.

Wismut Kristall und 1cm3 Wuerfel
Wismut Kristall und 1cm3 Wuerfel

Bismuth is also hard to use to move heat. It has one of the lowest thermal conductivities of any metal. This means heat does not move through it very fast. Another strange thing happens when it freezes. Most things shrink when they get cold. Bismuth actually expands by 3.32% as it turns from a liquid to a solid.

Bi phase diagram
Bi phase diagram

This expansion is very helpful. It was used to make metal type for printing. The metal would expand to fill every tiny corner of a mold.

People have known about bismuth since ancient times. No single person is credited with finding it. In the past, it was often confused with tin or lead. This was because it looks similar to those metals.

Processing of bismuth. Etching. Wellcome V0023568
Processing of bismuth. Etching. Wellcome V0023568

The name "bismuth" might come from old German words. These words might mean "white mass." A man named Georgius Agricola wrote about it in 1546. He said it was a distinct metal. Later, scientists like Carl Wilhelm Scheele helped prove it was different from lead. In 1753, Claude François Geoffroy also showed it was its own unique element. This helped people understand exactly what it was.

Bismuth is very useful in our world today. It is much less toxic than lead. Because of this, many people use bismuth alloys to replace lead.

Bismuthvanadat
Bismuthvanadat

About one third of the world's bismuth is used for this. It is also used in cosmetics and pigments. Some medicines use bismuth to help treat diarrhea.

Bismite
Bismite

Most bismuth is not mined by itself. Instead, it is found while refining other metals. It is a byproduct of mining copper, tin, or tungsten. In 2016, about 10,200 tonnes were mined. Another 17,100 tonnes were made by refining. This shows how much we rely on this metal in many different ways.

Scientists also study bismuth to learn about the universe. For a long time, people thought bismuth was stable. They thought it was the heaviest element that did not decay.

However, researchers in France found something new in 2003. They discovered that bismuth-209 is actually slightly radioactive. It undergoes something called alpha decay. This means it breaks down very, very slowly. Its half-life is a billion times longer than the age of the universe.

Bismuth(III) oxide 2
Bismuth(III) oxide 2

This makes it very safe for most jobs. Even though it is radioactive, it is still used in medicine. Some special versions of bismuth are even used to help treat cancer.

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🖼️ Images & Media (10)
File:Bismuth symbol.svg
Bismuth symbol.svg
File:Wismut Kristall und 1cm3 Wuerfel.jpg
Wismut Kristall und 1cm3 Wuerfel.jpg
File:Bi phase diagram.png
Bi phase diagram.png
File:Bismuth(III)_oxide_2.jpg
Bismuth(III)_oxide_2.jpg
File:MatlockiteStructure.png
MatlockiteStructure.png
File:Bismite.jpg
Bismite.jpg
File:BrokenBismuthIngot.jpg
BrokenBismuthIngot.jpg
File:BiPrice.png
BiPrice.png
File:Processing of bismuth. Etching. Wellcome V0023568.jpg
Processing of bismuth. Etching. Wellcome...
File:Bismuthvanadat.jpg
Bismuthvanadat.jpg
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