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Cerium

physical science Maturity 7-9 Next article →

Cerium is a soft, silvery-white metal.

Ceric ammonium nitrate
Ceric ammonium nitrate

It belongs to a group called the lanthanides. These are often called rare-earth elements. Cerium is actually the most common of all the lanthanides. It is found in the Earth's crust at about 68 parts per million. This metal is quite special because it can change its state easily. Most lanthanides use three electrons for their chemistry. However, cerium can also use four. This unique ability makes it stand out from its neighbors.

Bastnaesite crystal structure
Bastnaesite crystal structure

How does cerium work in the world? It works by changing its electronic structure. This means its electrons can move around in different ways. For example, cerium can change its volume by about 10 percent. This happens when it faces high pressure or very low temperatures. When it gets cold or squeezed, it shifts from one state to another. It also reacts with the air. When exposed to air, it tarnishes. This creates a thin layer on the surface, much like how iron gets rust.

Cerium phase diagram
Cerium phase diagram

People discovered cerium a long time ago. In 1803, two men in Sweden found it. Their names were Jöns Jakob Berzelius and Wilhelm Hisinger. At the same time, Martin Heinrich Klaproth found it in Germany. They named the metal after the asteroid Ceres.

Ceres - RC3 - Haulani Crater (22381131691)
Ceres - RC3 - Haulani Crater (22381131691)

Back then, people thought Ceres was a planet. It was named after the Roman goddess of agriculture. Later, Carl Gustaf Mosander separated cerium oxide in 1839. Finally, William Francis Hillebrand isolated the pure metal in 1875.

Jöns Jacob Berzelius x Johan Way
Jöns Jacob Berzelius x Johan Way

Cerium is used in many things we see every day. One important use is in catalytic converters. These help clean up gases from car engines. Another use is for polishing glass. Cerium(IV) oxide is a great tool for this job. You can also find cerium in lighters. It is pyrophoric, which means it can catch fire easily. This property helps create sparks.

5 mm Tinted White LED (on)
5 mm Tinted White LED (on)

Have you ever looked at a bright white LED light? Cerium might be helping to make that light. Many white LEDs use a special material called a phosphor. This phosphor is doped with cerium. It takes the blue light from the diode and turns it into white light. This is how most commercial white lights work today. Cerium is a tiny part of a very big world of science. It connects the rocks in the ground to the lights in your home.

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🖼️ Images & Media (7)
File:Cerium phase diagram.jpg
Cerium phase diagram.jpg
File:Ceric ammonium nitrate.jpg
Ceric ammonium nitrate.jpg
File:5 mm Tinted White LED (on).jpg
5 mm Tinted White LED (on).jpg
File:Ceres - RC3 - Haulani Crater (22381131691).jpg
Ceres - RC3 - Haulani Crater (22381131691).jpg
File:Jöns Jacob Berzelius x Johan Way.jpg
Jöns Jacob Berzelius x Johan Way.jpg
File:Bastnaesite crystal structure.png
Bastnaesite crystal structure.png
File:Auer von Welsbach.jpg
Auer von Welsbach.jpg
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