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Lanthanum - La

Chemical properties of lanthanum - Health effects of lanthanum - Environmental effects of lanthanum

Atomic number

57

Atomic mass

138.91 g.mol -1

Electronegativity according to Pauling

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 - La

Lanthanum

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.

Lanthanium in the environment

Lanthanum can rarely be found in nature, as it occurs in very small amounts. It is anyway one of the more abundant rare-earch elements. Lanthanum is usually found only in two different kinds of ores. World production of lanthanum oxide in around 12.000 tonnes per year, and currently nown reseves of lanthanum are around 6 million tonnes.

The use of lanthanum is still growing, due to the fact that it is suited to produce catalysers and to polish glass.

Health effects of lanthanum

Lanthanum is mostly dangerous in the working environment, due to the fact that damps and gasses can be inhaled with air. This can cause lung embolisms, especially during long-term exposure. Lanthanum can also cause cancer with humans, as it enlarges the chances of lung cancer when it is inhaled. Finally, it can be a threat to the liver when it accumulates in the human body.

Environmental effects of lanthanum

Lanthanum is dumped in the environment in many different places, mainly by petrol-producing industries. It can also enter the environment when household equipment is thrown away. Lanthanum will gradually accumulate in soils and water soils and this will eventually lead to increasing concentrations in humans, animals and soil particles.

With water animals Lanthanum causes damage to cell membranes, which has several negative influences on reproduction and on the functions of the nervous system. It strongly accumulates in mussels.

Back to chart periodic table of elements.


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