lantano

Lanthanum (La) is a chemical element with atomic number 57 and a soft, silvery-white metal that tarnishes in air and reacts with water. It is the first element in the lanthanide series and is commonly classified among the rare earth elements. In nature, lanthanum does not occur free; it is found in minerals such as monazite and bastnäsite, from which it is extracted and refined.

Chemically, lanthanum has the electron configuration [Xe] 5d1 6s2. Its chemistry is dominated by the La3+ ion; the +3 oxidation state is the most stable in compounds, though +2 and +4 can appear in certain environments. Common compounds include La2O3, LaF3, LaCl3, and La2(CO3)3. Lanthanum forms several phosphors and is used as a component in glass and ceramic additives, catalysts for petroleum refining and emissions control, and in advanced materials such as lanthanum-based perovskites for fuel cells. Lanthanum-containing scintillators, such as LaBr3:Ce, are used in radiation detectors, and LaB6 is employed as an electron-emissive material.

Occurrence and production typically involve ore processing of monazite or bastnäsite to concentrate lanthanum, convert it to lanthanum oxide, and then refine it to metal or use the oxide directly in applications. The metal is relatively reactive and is usually produced in alloy form or as compounds for industrial use.

History and name: lanthanum was identified in 1839 by Carl Gustaf Mosander during purification of cerium compounds. The name derives from the Greek lanthanein, meaning to lie hidden. Natural lanthanum consists mainly of the stable isotope 139La, with other isotopes having very long half-lives.

Safety and environment: lanthanum compounds are generally of low acute toxicity but should be handled with standard precautions to avoid inhalation of dust.