cerium

American  

[seer-ee-uhm] / ˈsɪər i əm /

noun

1. a steel-gray, ductile metallic element of the rare-earth group found only in combination. Ce; 140.12; 58.

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cerium British  

/ ˈsɪərɪəm /

noun

1. a malleable ductile steel-grey element of the lanthanide series of metals, used in lighter flints and as a reducing agent in metallurgy. Symbol: Ce; atomic no: 58; atomic wt: 140.115; valency: 3 or 4; relative density: 6.770; melting pt: 798°C; boiling pt: 3443°C

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cerium Scientific  

/ sîr′ē-əm /

1. A shiny, gray metallic element of the lanthanide series. It is ductile and malleable and is used in electronic components, alloys, and lighter flints. It is also used in glass polishing, as a catalyst in self-cleaning ovens, and in various nuclear applications. Atomic number 58; atomic weight 140.12; melting point 795°C; boiling point 3,468°C; specific gravity 6.67 to 8.23; valence 3, 4.

2. See Periodic Table

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Etymology

Origin of cerium

First recorded in 1795–1805; Cer(es) + -ium

Example Sentences

Valor has designed reusable ligands for 10 elements, including gold, copper, platinum, nickel and a number of otherwise difficult-to-isolate rare earths, including cerium, dysprosium and yttrium.

From The Wall Street Journal • Mar. 11, 2026

In the chemical industry, cerium is widely used in oil refining and glass polishing -- as well as in flints for cigarette lighters.

From Barron's • Feb. 4, 2026

"The objective of the liquid separation unit will be to purify cerium on one side, lanthanum on the other side," explains production manager Florian Gouneau as we walk up a flight of metal stairs.

From BBC • Aug. 6, 2025

Inside this reactor, which contains a porous ceramic structure made of cerium oxide, a thermochemical cycle takes place for splitting water and CO2 captured previously from the air.

From Science Daily • Oct. 27, 2023

These mantles contain the oxides of cerium and thorium in the ratio of about 1% of the former to 99% of the latter.

From An Elementary Study of Chemistry by McPherson, William