Lanthanum

Source of the photo
http://nl.wikipedia.org/wiki/Lanthanium
Author of the description
Gruiz Katalin

Atomic number

57

Atomic mass

138.91 g.mol -1

Electronegativity

1.1

Density

6.18 g.cm-3 at 20°C

Melting point

826 °C

Boiling point

0.186 nm

Vanderwaals radius

0.104 nm (+3)

Isotopes

7

Electronic shell

[ Xe ] 5d1 6s2

Energy of first ionisation

539 kJ.mol -1

Energy of second ionisation

1098 kJ.mol -1

Energy of third ionisation

1840 kJ.mol -1

Standard potential

- 2.52 V ( La+3/ La )

Discovered by

Carl Mosander in 1839

 

Lanthanum is a soft, malleable, ductile, silver-white metal. It is chemically active, it is one of the most reactive of the rare-earth metals: it oxidizes rapidly in air and it reacts with water to form the hydroxide. Lanthanum is easily ignited, its salts are often very insoluble.

Applications

Lanthanum is one of the rare chemicals, that can be found in houses in equipment such as colour televisions, fluorescent lamps, energy-saving lamps and glasses. All rare chemicals have comparable properties. La2O2 is used to make special optical glasses (infrared adsorbing glass, camera and telescope lenses). If added in small amounts it improves the malleability and resistence of steel. Lanthanum is used as the core material in carbon arc electrodes. Lanthanum salts are included in the zeolite catalysts used in petroleum refining because thay stabilize the zeolite at high temperatures.