Cerium
Definition and meaning of Cerium in chemistry.
![Cerium element card: symbol Ce, atomic number 58, atomic mass 140.12, electron configuration [Xe] 4f¹ 5d¹ 6s², oxidation states +4 +3, Lanthanide, f-block, period 6, solid at room temperature.](/assets/images/terms/cerium-chemical-element.webp)
Cerium is a chemical element with the symbol Ce and atomic number 58. It is a soft, ductile, and silvery-white metal. The metal tarnishes rapidly when it is exposed to the oxygen in air. Cerium is the most abundant of the rare-earth metals. Miners extract it primarily from minerals like monazite and bastnasite.
In more detail
Cerium sits in the f-block of the periodic table. It is the second element in the lanthanide series. Cerium exhibits unique chemical behavior compared to similar metals.
It easily transitions between the +3 and +4 oxidation states. Most other lanthanides strongly favor only the +3 state. In its +4 state, cerium acts as a remarkably strong oxidizing agent.
An oxidizing agent is a substance that readily removes electrons from other chemicals. This property makes cerium highly useful in quantitative chemical analysis. It also plays a key role in various industrial redox reactions.
Furthermore, cerium is a highly reactive metal. It can ignite spontaneously if scratched or filed. Scientists call this specific property pyrophoricity.
The solid metal reacts slowly with cold water. It reacts much more rapidly with hot water to form cerium(III) hydroxide and hydrogen gas. Despite belonging to the rare-earth category, cerium is relatively abundant.
It occurs in the Earth's crust at levels comparable to copper. In fact, cerium represents nearly half of all naturally occurring rare-earth elements.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Ce |
| Atomic number | 58 |
| Atomic mass | 140.12 u |
| Category | Lanthanide |
| State at room temperature | Solid |
| Year discovered | 1803 |
Manufacturers widely use cerium in the form of cerium(IV) oxide. They apply this compound as a highly effective glass polishing agent for optical lenses. The automotive industry also uses cerium extensively in catalytic converters. The element helps these devices reduce toxic exhaust emissions from cars and trucks. This specific application significantly improves air quality in modern urban environments.
Frequently asked questions
Is cerium a rare element?
Despite being classified as a rare-earth metal, cerium is quite common. It is the 25th most abundant element in the Earth's crust. This makes it more common than familiar metals like lead or tin.
What causes the sparks in lighter flints?
Lighter flints are made of mischmetal. This is a special alloy primarily composed of cerium. It sparks easily when struck because of its pyrophoric nature.
Related terms
Sources & references
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