lantanidien

Lantanidien, also known as lanthanum, is a chemical element with the symbol La and atomic number 57. It is a silvery-white metal that belongs to the lanthanide series of the periodic table. Lantanidien is the first element in the lanthanide series and is traditionally considered to be one of the rare earth elements. It is relatively stable in air and does not oxidize as rapidly as some other rare earth metals.

Lantanidien is primarily obtained from the mineral monazite and bastnasite through various separation processes. Its most common oxidation state is +3, although it can also exhibit the +2 oxidation state. Lantanidien is used in various applications, including as a catalyst in the conversion of petroleum to gasoline, as an additive in glass and ceramics to improve their optical properties, and in carbon arc lighting. It is also used in the production of high-strength alloys and as a component in nickel-metal hydride batteries.

Lantanidien has several isotopes, with the most stable being lanthanum-139, which has a half-life of over 10^10 years. The element is not known to have any significant biological role and is generally considered to be of low toxicity. However, like other rare earth elements, it can be hazardous if inhaled or ingested in large quantities.