- a rare-earth, trivalent, metallic element, allied to aluminum, found in certain minerals, as monazite. Symbol: La; atomic weight: 138.91; atomic number: 57; specific gravity: 6.15 at 20°C.
Origin of lanthanum
Examples from the Web for lanthanum
Not to mention rare elements such as lanthanum, cerium, and neodymium, essential to modern technology and commanding high prices.Afghanistan’s Mineral Wealth Could Be a Bonanza—or Lead to Disaster
Dr. Cheryl Benard
July 4, 2012
Lanthanum, lan′tha-num, n. a metal discovered in 1839 in cerite, a hydrated silicate of cerium.
Didymium, a rare metallic element, occurring along with lanthanum in the mineral cerite as discovered by Mosander in 1842.The New Gresham Encyclopedia
During an absence of several days, the inventor left a mantle of lanthanum oxide locked up in his laboratory.Inventors at Work
Lanthanum hydroxide, La(OH)3, is a white amorphous powder formed by precipitating lanthanum salts by potassium hydroxide.
Lanthanum sulphide, La2S3, is a yellow powder, obtained when the oxide is heated in the vapour of carbon bisulphide.
- 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
Word Origin and History for lanthanum
metallic rare earth element, 1841, coined in Modern Latin by Swedish chemist and mineralogist Carl Gustav Mosander (1797-1858), who discovered it in 1839, from Greek lanthanein "to lie hidden, escape notice," from PIE root *ladh- "to be hidden" (see latent). So called because the element was "concealed" in rare minerals.
- A soft malleable metallic rare-earth element used in glass manufacture. Atomic number 57.
- 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.