lanthanum

[ lan-thuh-nuhm ]

noun

, Chemistry.

1. a rare-earth, trivalent, metallic element, allied to aluminum, found in certain minerals, as monazite. : La; : 138.91; : 57; : 6.15 at 20°C.

lanthanum

/ ˈlænθənəm /

noun

1. 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

lanthanum

/ lăn′thə-nəm /

1. 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.
2. See Periodic Table

Word History and Origins

Origin of lanthanum¹

< New Latin (1841), equivalent to lanthan- (< Greek lanthánein to escape notice; referring to its position on the periodic table) + -um, variant of -ium -ium

Word History and Origins

Origin of lanthanum¹

C19: New Latin, from Greek lanthanein to lie unseen

Example Sentences

Most rare earth elements are lanthanides, elements from 57 -- lanthanum -- to 71 -- lutetium -- on the periodic table.

From Science Daily

But, at room temperature, the number of hydrogens attached to lanthanum fluctuates between 2 and 3, making it impossible to have efficient conduction.

From Science Daily

Loeb says traces of three rare elements — beryllium, lanthanum and uranium — suggest the spheres come from outside of our solar system.

From Salon

However, five of the spherules were unusually enriched in beryllium and lanthanum, and, to a lesser degree, uranium.

From Science Magazine

The 17 elements are: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, yttrium.

From Reuters