Lanthanum is a ductile and malleable silvery white metal that is soft enough to be cut with a knife. It is the second most reactive of the rare-earth metals after europium. Lanthanum oxidizes in air at room temperature to form La2O3. It slowly reacts with water and quickly dissolves in diluted acids, except hydrofluoric acid (HF) because of formation of a protective fluoride (LaF3) layer on the surface of the metal. Continue reading from Encyclopedia Britannica
The element was discovered as the oxide (lanthana) in 1839 by Carl Gustaf Mosander, who distinguished it from cerium oxide (ceria). Its name is derived from the Greek lanthanein, meaning “to be concealed,” indicating that it is difficult to isolate. Lanthanum occurs in the rare-earth minerals monazite and bastnasite. It is as abundant as cobalt in Earth’s upper continental crust. Continue reading from Encyclopedia Britannica
Swedish chemist Carl Gustaf Mosander extracted lanthanum oxide, or lanthana, from an impure cerium nitrate in 1839. In 1923, a relatively pure form of lanthanum was isolated. Lanthanum is silvery white, malleable, ductile and so soft you can slice it with a knife. It is one of the most reactive rare-earth metals, which are also called lanthanides. The element reacts with elemental carbon, nitrogen, boron, selenium, silicon, phosphorus, sulfur, and also with halogens.
As a rare-earth metal, lanthanum is found in rare-earth minerals such as cerite, monazite, allanite and bastnasite. In monazite and bastnasite, lanthanum can be found in percentages up to 25 percent and 38 percent respectively. Lanthanum and other rare-earth compounds are used in carbon arc lighting, specifically in the film and television industry for studio lighting and projection. Lanthanum oxide (La2O3), also called lanthana, improves the alkali resistance of glass and is used in making camera lenses and in other special glasses. About 25 percent of the alloy mischmetal, used in making lighter flints, contains lanthanum. As an additive, small amounts of lanthanum are used to produce nodular cast iron. Continue reading from Live Science
