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Author: langbot
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English[en]
Lanthanum is a chemical element with the symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table, of which lanthanum is the first and the prototype. Lanthanum is traditionally counted among the rare earth elements. Like most other rare earth elements, the usual oxidation state is +3. Lanthanum has no biological role in humans but is essential to some bacteria. It is not particularly toxic to humans but does show some antimicrobial activity. Lanthanum usually occurs together with cerium and the other rare earth elements. Lanthanum was first found by the Swedish chemist Carl Gustaf Mosander in 1839 as an impurity in cerium nitrate – hence the name lanthanum, from the Ancient Greek λανθάνειν (lanthanein), meaning 'to lie hidden'. Although it is classified as a rare earth element, lanthanum is the 28th most abundant element in the Earth's crust, almost three times as abundant as lead. In minerals such as monazite and bastnäsite, lanthanum composes about a quarter of the lanthanide content.[6] It is extracted from those minerals by a process of such complexity that pure lanthanum metal was not isolated until 1923. Lanthanum compounds have numerous applications as catalysts, additives in glass, carbon arc lamps for studio lights and projectors, ignition elements in lighters and torches, electron cathodes, scintillators, gas tungsten arc welding electrodes, and other things. Lanthanum carbonate is used as a phosphate binder in cases of high levels of phosphate in the blood seen with kidney failure.
Cornish[kw]
Elven gymyk yw lanthanom, niver 57 y'n Vosen Beriodek. Y furvell gymyk yw La. An hanow a dheu dhyworth an ger Greka lanthanein, ow styrya growedha yn kel. Onan a'n elvennow gelwys dor-tanow yw mes kamm yw an hanow ma awos nyns yw re anedha tanow vytholl. Lanthanid via term gwell, hanow a dheu dhyworth an elven ma. Nyns eus rann dhe lanthanom y'n korf denel, mes usys yw lanthanom avel medhegneth dhe weres pobel gans kudynnow loneth. Diskudhys veu lanthanom yn mis Genver 1839 gans Carl Gustav Mosander (1797-1858) y'n Fondyans Karolinska, Stockholm. Ev a hwithras ceriom nitrat hag ev a gavas gwrysow elven 'nowydh' dhyworto. Y goweth Baron Jöns Jacob Berzelius a grampollas an hanow lanthanom. An moon monazit a gomprehend a-dro dhe 25% lanthanom. Askorrys yw 12,500 tonnas an vledhen, dre vras y'n Statys Unys, China ha Russi. Usys yw avel kesalkenyow, rag ensampel lanthanom ha nikel - LaNi5 yw pur dha rag sugna an gass hidrojen (da vydh hemma y'n termyn a dheu mars usys yw hidrojen avel keunys). Usys yw meur a lanthanom dhe wul batriow nikel-alkan hydrid La(Ni3.6Mn0.4Al0.3Co0.7). Usys yw avel katalydhyon, avel kathodow pooth yn pibennow gwakter elektronek, hag yn livwolowys. Poos atomek lanthanom yw 138.91, y boynt teudhi yw 921°C ha'y boynt bryjyon 3460°C. Y dhosedh yw 6.1kg an liter. Alkan arghansek yw, medhel lowr dhe dreghi gan kollell.