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The Element Lanthanum

[Click for Isotope Data]





Atomic Number: 57

Atomic Weight: 138.90547

Melting Point: 1191 K (918°C or 1684°F)

Boiling Point: 3737 K (3464°C or 6267°F)

Density: 6.15 grams per cubic centimeter

Phase at Room Temperature: Solid

Element Classification: Metal

Period Number: 6    Group Number: none    Group Name: Lanthanide

What's in a name? From the Greek word lanthaneia, which means "to lie hidden."

Say what? Lanthanum is pronounced as LAN-the-nem.

History and Uses:

Lanthanum was discovered by Carl Gustaf Mosander, a Swedish chemist, in 1839. Mosander was searching for impurities he believed existed within samples of cerium. He treated cerium nitrate (Ce(NO3)3) with dilute nitric acid (HNO3) and found a new substance he named lanthana (La2O3). Roughly 0.0018% of the earth's crust is composed of lanthanum. Today, lanthanum is primarily obtained through an ion exchange process from monazite sand ((Ce, La, Th, Nd, Y)PO4), a material rich in rare earth elements that can contain as much as 25% lanthanum.

Lanthanum is one of the rare earth elements used to make carbon arc lights which are used in the motion picture industry for studio lighting and projector lights. Lanthanum also makes up about 25% of Misch metal, a material that is used to make flints for lighters. Lanthana (La2O3) is used to make the glass used in camera lenses and in other special glasses.

Estimated Crustal Abundance: 3.9×101 milligrams per kilogram

Estimated Oceanic Abundance: 3.4×10-6 milligrams per liter

Number of Stable Isotopes: 1   (View all isotope data)

Ionization Energy: 5.577 eV

Oxidation States: +3

Electron Shell Configuration:


2s2   2p6

3s2   3p6   3d10

4s2   4p6   4d10

5s2   5p6   5d1