lanthaan

Lanthaan is the Dutch name for lanthanum, a chemical element with the symbol La and atomic number 57. It is the first element in the lanthanide series, a group of f-block metals often mined together as rare earth elements. The name lanthanum is derived from Greek lanthanein, meaning to lie hidden, a reference to its late recognition as a distinct element in the 19th century. Lanthanum occurs in minerals rather than in free form.

Physically lanthanum is a soft, silvery-white metal that tarnishes in air and is relatively reactive. It is commonly trivalent (+3) in compounds, with rare examples of +2 or +4 oxidation states. In pure form it can be cut with a knife. Its most common oxide is La2O3, and many lanthanum salts are soluble in water.

Occurrence and production: Lanthanum is a rare earth element found in minerals such as monazite and bastnäsite. Although relatively abundant in the Earth's crust, it is rarely present as a free metal. It is mined mainly in China, Australia, and the United States, and separated from other lanthanides through complex hydrometallurgical and metallurgical processes to yield refined metal or high-purity salts used in industry.

Uses: Lanthanum and its compounds are employed as catalysts in petroleum refining and in various chemical processes. La2O3 and related materials are used in glass and ceramic additives to adjust refractive properties and color. In alloys and phosphors, lanthanum compounds play roles in specialty electronics and lighting applications. It also features in nickel–metal hydride battery chemistries as part of rare-earth alloys.

Safety and isotopes: Lanthanum compounds are of relatively low acute toxicity, with standard handling precautions for reactive metals and inorganic salts. Naturally occurring lanthanum is dominated by 139La; trace radioactive isotopes exist but are present only in minute amounts.