lanthanum

lanthanum
Name	Lanthanum
Atomic number	57
Category	Lanthanide
Appearance	Silvery-white metal
Atomic weight	138.90547
Phase	Solid
Density	6.162 g/cm3
Melting point	1193 °C
Boiling point	3737 °C
Electron configuration	[Xe] 5d1 6s2

lanthanum is a chemical element with atomic number 57 and is the first element of the lanthanide series. It is a silvery-white, ductile metal used as a precursor for a wide range of alloys, catalysts, and optical materials. Lanthanum appears in rare-earth mineral deposits and is refined for industrial uses in electronics, glassmaking, and energy technologies.

Characteristics

Lanthanum exhibits metallic bonding and crystallizes in a hexagonal close-packed structure at room temperature; its properties are intermediate between those of cerium and cerium(III) compounds and those of the heavier lanthanides such as neodymium and samarium. The element has an electron configuration that follows xenon core occupancy and contributes to its +3 oxidation state, which is predominant in compounds analogous to those of calcium and scandium. Physically, lanthanum's density, melting point, and malleability are comparable to those of praseodymium and promethium neighbors, and its chemical behavior—particularly complexation and coordination chemistry—resembles that of yttrium and lanthanide contraction-related elements. Spectroscopically, lanthanum shows weak 4f–5d transitions compared with europium and terbium, influencing its role in optical materials used alongside ytterbium and erbium dopants.

Occurrence and Extraction

Lanthanum is typically found in rare-earth minerals such as bastnäsite, monazite, and oxfordite (rare), occurring in mineral deposits associated with pegmatites and carbonatites like those at Mountain Pass, California, Bayan Obo, and Madagascar. Commercial extraction usually begins with mining operations controlled by companies linked to regions such as China, United States Department of Energy-influenced sites, and firms operating in Brazil and Australia. Processing involves beneficiation, separation of light rare-earth elements using solvent extraction techniques inspired by work from laboratories such as Oak Ridge National Laboratory and industrial chemists from Union Carbide-era projects, and refining by electrolysis or thermal reduction methods developed in collaboration with researchers at institutions like Massachusetts Institute of Technology and Max Planck Institute affiliates. Historical supply chains have been affected by policies and trade interactions involving World Trade Organization considerations and strategic material initiatives of governments including Japan and European Commission.

Production and Applications

Primary lanthanum production is driven by demand for catalysts, glass additives, and battery materials supplied to manufacturers such as General Motors, Toyota, and electronics firms like Samsung and Apple. Lanthanum oxide and salts are key in catalyst formulations for petroleum refining technologies pioneered by companies such as ExxonMobil and in automobile catalytic converters introduced by Ford Motor Company and Bosch. Optical glass containing lanthanum oxide, used in camera lenses for makers like Nikon and Canon, improves refractive index and chromatic aberration control alongside glass technologies advanced at Corning Incorporated. Lanthanum-based alloys, including those used in nickel-metal hydride batteries developed in collaborations involving Panasonic and Toyota, enhance hydrogen storage capacity; these alloys are related to research performed at Argonne National Laboratory. Emerging applications link lanthanum compounds to hydrogen fuel cell research at institutions like Ballard Power Systems and to phosphor technologies commercialized by companies such as Philips and Osram.

Compounds and Chemistry

Lanthanum forms stable +3 compounds, including lanthanum oxide, lanthanum chloride, and lanthanum nitrate, comparable in stoichiometry to salts of alkaline earth metals such as calcium but with distinctive coordination chemistry studied at universities like Harvard University and University of Cambridge. Lanthanum oxide (La2O3) is hygroscopic and used as a starting material for producing lanthanum alkoxides and organolanthanum reagents developed within research groups at California Institute of Technology and ETH Zurich. Complexes of lanthanum coordinate with ligands investigated by chemists affiliated with Nobel Prize-winning laboratories; these complexes have been applied in homogeneous catalysis and polymerization processes similar to systems explored by teams at Dow Chemical Company and DuPont. Solid-state chemistry includes perovskite-structured materials such as lanthanum manganite used in fuel cells and electrodes studied by researchers at MIT and National Renewable Energy Laboratory.

Biological Effects and Toxicity

Lanthanum has low bioavailability and accumulates minimally in organisms compared with transition metals studied in toxicology by institutes like Centers for Disease Control and Prevention and World Health Organization. Certain lanthanum salts, for example lanthanum carbonate used in clinical contexts to control phosphate in patients with chronic kidney disease, were evaluated in clinical trials overseen by regulatory bodies such as the U.S. Food and Drug Administration and European Medicines Agency. Occupational exposure limits and handling guidelines are set following standards promulgated by organizations including Occupational Safety and Health Administration and National Institute for Occupational Safety and Health; long-term environmental impacts are subjects of study by agencies such as Environmental Protection Agency and university toxicology programs at Johns Hopkins University.

History and Etymology

Lanthanum was discovered in 1839 by the Swedish chemist Carl Gustav Mosander while working at laboratories connected to contemporaries like Jöns Jakob Berzelius and within the broader 19th-century chemical research community that included figures such as Dmitri Mendeleev and John Newlands. Its name derives from the Greek verb meaning "to lie hidden," reflecting its discovery within the mineral monazite and the era's analytic methods developed at institutions like Royal Society-affiliated laboratories. Throughout the 20th century, industrialization of rare-earth extraction involved companies and governments including U.S. Bureau of Mines, Union Minière, and later state enterprises in China that influenced global supply and technology integration across industries represented by firms like Siemens and General Electric.

Category:Chemical elements