lanthanum

lan·tha·num  (lnth-nm)

n. Symbol La

A soft, silvery-white, malleable, ductile, metallic rare-earth element, obtained chiefly from monazite and bastnaesite and used in glass manufacture and with other rare earths in carbon lights for movie and television studio lighting. Atomic number 57; atomic weight 138.91; melting point 920°C; boiling point 3,469°C; specific gravity 5.98 to 6.186; valence 3. See Table at element.

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[New Latin, from Greek lanthanein, to escape notice (from the finding of the element hidden in oxide of cerium).]

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lanthanum [ˈlænθənəm]

n

(Chemistry / Elements & Compounds) a silvery-white ductile metallic element of the lanthanide series, occurring principally in bastnaesite and monazite: used in pyrophoric alloys, electronic devices, and in glass manufacture. Symbol: La; atomic no.: 57; atomic wt.: 138.9055; valency: 3; relative density: 6.145; melting pt.: 918°C; boiling pt.: 3464°C

[New Latin, from Greek lanthanein to lie unseen]

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lanthanum  (lnth-nm)

Symbol La

A soft, malleable, silvery-white metallic element of the lanthanide series. It is used to make glass for lenses and lights for movie and television studios. Atomic number 57; atomic weight 138.91; melting point 920°C; boiling point 3,469°C; specific gravity 5.98 to 6.186; valence 3. See Periodic Table.

Thesaurus

Noun

1.

lanthanum - a white soft metallic element that tarnishes readily; occurs in rare earth minerals and is usually classified as a rare earth atomic number 57, La metal, metallic element - any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.