Cerium
Definition and meaning of Cerium in chemistry.
Cerium is a chemical element with the symbol Ce and atomic number 58. It is a soft, ductile, and silvery-white metal that tarnishes rapidly when exposed to air. As the most abundant of the rare-earth metals, it is found in minerals like monazite and bastnasite.
In more detail
Located in the f-block of the periodic table, cerium is the second element in the lanthanide series. It exhibits unique chemical behavior due to its ability to easily transition between the +3 and +4 oxidation states, unlike most other lanthanides which strongly favor only the +3 state. In its +4 state, it acts as a remarkably strong oxidizing agent, making it highly useful in quantitative chemical analysis and various industrial redox reactions. Cerium is a highly reactive metal that can ignite spontaneously if scratched or filed, a property known as pyrophoricity. It reacts slowly with cold water and rapidly with hot water to form cerium(III) hydroxide and hydrogen gas. Despite belonging to the rare-earth category, it is relatively abundant in the Earth's crust, occurring at levels comparable to copper and representing nearly half of the 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 |
| Melting point | 795 °C |
| Year discovered | 1803 |
Cerium is widely used in the form of cerium(IV) oxide as a glass polishing agent and in catalytic converters for automobiles to reduce toxic exhaust emissions.
Frequently asked questions
Is cerium a rare element?
Despite being classified as a rare-earth metal, cerium is the 25th most abundant element in the Earth's crust, making it more common than lead or tin.
What causes the sparks in lighter flints?
Lighter flints are made of mischmetal, an alloy primarily composed of cerium, which sparks easily when struck due to its pyrophoric nature.