cerium

[seer-ee-uhm]
noun
a steel-gray, ductile metallic element of the rare-earth group found only in combination. Symbol: Ce; atomic weight: 140.12; atomic number: 58.

Origin:
1795–1805; Cer(es) + -ium

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World English Dictionary
cerium (ˈsɪərɪəm)
 
n
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
 
[C19: New Latin, from Ceres (the asteroid) + -ium]

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Medical Dictionary

cerium ce·ri·um (sēr'ē-əm)
n.
Symbol Ce
A lustrous, malleable metallic rare-earth element that occurs chiefly in the minerals monazite and bastnaesite, exists in four allotropic states, and is used in lighter flint alloys. Atomic number 58; atomic weight 140.12; melting point 799°C; boiling point 3,424°C; specific gravity 6.67; valence 3, 4.

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Science Dictionary
cerium   (sîr'ē-əm)  Pronunciation Key 
Symbol Ce
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 and as a catalyst in self-cleaning ovens. 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. See Periodic Table.
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Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Example sentences
The catalytic converter on your exhaust system contains cerium and lanthanum.
Cerium usually plays a supporting role to platinum, which is a more active catalyst but also more expensive.
Some companies are claiming to have done exactly that, by manufacturing fuel additives made of nanometer-sized cerium particles.
Both cerium and aluminum form many useful alloys with other metals.
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