Lanthanum is a chemical element with the symbol "La" and atomic number 57. Lanthanum is a silvery white metallic element that belongs to group 3 of the periodic table and is the first element of the lanthanide series. It is found in some rare- earth minerals, usually in combination with cerium and other rare earth elements. Lanthanum is a malleable, ductile, and soft metal that oxidizes rapidly when exposed to air. It is produced from the minerals monazite and bastnäsite using a complex multistage extraction process. Lanthanum compounds have numerous applications as catalysts, additives in glass, carbon lighting for studio lighting and projection, ignition elements in lighters and torches, electron cathodes, scintillators, and others. Lanthanum carbonate (La2(CO3)3) was approved as a medication against renal failure. Lanthanum is a soft, malleable, silvery white metal which has hexagonal crystal structure at room temperature. At 310 °C, lanthanum changes to a face-centered cubic structure, and at 865 °C into a body-centered cubic structure. Lanthanum exhibits two oxidation states, +3 and +2, the former being much more stable. For example, LaH3 is more stable than LaH2. Lanthanum burns readily at 150 °C to form lanthanum(III) oxide: 4 La + 3 O2 → 2 La2O3 The word lanthanum comes from the Greek λανθανω [lanthanō] = to lie hidden. Lanthanum was discovered in 1839 by Swedish chemist Carl Gustav Mosander, when he partially decomposed a sample of cerium nitrate by heating and treating the resulting salt with dilute nitric acid. From the resulting solution, he isolated a new rare earth he called lantana. Lanthanum was isolated in relatively pure form in 1923. The alternative technique of fractional crystallization was invented by Dmitri Mendeleev, in the form of the double ammonium nitrate tetrahydrate, which he used to separate the less-soluble lanthanum from the more-soluble didymium in the 1870s. Although lanthanum belongs to the element group called rare earth metals, it is not rare at all. Lanthanum is available in relatively large quantities (32 ppm in Earth’s crust). "Rare earths" got their name because they were indeed rare as compared to the "common" earths such as lime or magnesia, and historically only a few deposits were known. Lanthanum has no known biological role. The element is very poorly absorbed after oral administration and when injected its elimination is very slow. Lanthanum carbonate was approved as a medication named Fosrenol to absorb excess phosphate in cases of end-stage renal failure. Lanthanum has a low to moderate level of toxicity and should be handled with care. In animals, the injection of lanthanum solutions produces hyperglycaemia, low blood pressure, degeneration of the spleen and hepatic alterations. References: ^ Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics. CRC press. 2000. ISBN 0849304814. ^ C. R. Hammond (2000). The Elements, in Handbook of Chemistry and Physics 81st edition. CRC press. ISBN 0849304814. ^ "Rare-Earth Metal Long Term Air Exposure Test". Retrieved 2009-08-08. ^ Tsuchiya, T; Kumashiro, R; Tanigaki, K; Matsunaga, Y; Ishitsuka, Mo; Wakahara, T; Maeda, Y; Takano, Y et al. (Jan 2008). "Nanorods of endohedral metallofullerene derivative.". Journal of the American Chemical Society 130 (2): 450–1. doi:10.1021/ja710396n. ISSN 0002-7863. PMID 18095695. ^ Guan, L; Suenaga, K; Okubo, S; Okazaki, T; Iijima, S (Feb 2008). "Metallic Wires of Lanthanum Atoms Inside Carbon Nanotubes". Journal of the American Chemical Society 130 (7): 2162–3. doi:10.1021/ja7103069. ISSN 0002 -7863. PMID 18225905. ^ Patnaik, Pradyot (2003). Handbook of Inorganic Chemical Compounds. McGraw-Hill. pp. 444–446. ISBN 0070494398. Retrieved 2009-06-06. ^ "Chemical reactions of Lanthanum". Webelements. Retrieved 2009-06-06. ^ "Lighting". 11th edition of Encyclopedia Britannica (1911). Retrieved 2009-06-06. ^ "Inside the Nickel Metal Hydride Battery". Retrieved 2009-06-06. ^ Tliha, M; Mathlouthi, H; Lamloumi, J; Percheronguegan, A (2007). "AB5-type hydrogen storage alloy used as anodic materials in Ni- MH batteries". Journal of Alloys and Compounds 436: 221. doi:10.1016/j.jallcom.2006.07.012. ^ "As hybrid cars gobble rare metals, shortage looms". Reuters 2009-08-31. 2009-08- 31. ^ Bauerlein, P; Antonius, C; Loffler, J; Kumpers, J (2008). "Progress in high-power nickel–metal hydride batteries". Journal of Power Sources 176 (2): 547. doi:10.1016/j.jpowsour.2007.08.052. ^ Uchida, H (1999). "Hydrogen solubility in rare earth based hydrogen storage alloys". International Journal of Hydrogen Energy 24 (9): 871. doi:10.1016/S0360-3199(98)00161-X. ^ Jason D. Sommerville and Lyon B. King. "Effect of Cathode Position on Hall-Effect Thruster Performance and Cathode Coupling Voltage". 43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 8–11 July 2007, Cincinnati, OH. Retrieved 2009-06-06. [dead link]