Atomic number 57
Atomic mass 138.91 g.mol -1Density 6.18 g.cm-3 at 20°C Melting point 826 °C Boiling point 0.186 nm
Discovered by Carl Mosander in 1839Lanthanum 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.
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.
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.
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
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