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Chemical Elements

Lanthanium

lanthanide series, misch metal, lanthanum oxide, monazite, fluorspar

Lanthanum (Greek lanthanein, to escape notice), symbol La, metallic element with an atomic number of 57. Lanthanum is one of the rare earth elements of the periodic table. Lanthanum is often regarded as the first member of the lanthanide series, to which it gives its name.

Lanthanum was discovered by the Swedish chemist Carl Gustav Mosander in 1839. It burns in air at about 450C (about 842F) to form lanthanum oxide, La2O3. It forms colorless trivalent salts, including one of the strongest trivalent bases, which is used by analytical chemists. It generally occurs with other rare earth elements in such minerals as bastnasite and monazite and in certain kinds of calcite and fluorspar. It is fairly common, ranking 28th in order of abundance of the elements in Earth's crust. Impure lanthanum is used in alloys such as misch metal, of which lanthanum is a major constituent. Cigarette-lighter flints are made from this alloy. Lanthanum oxide is used in certain types of optical glass.

Lanthanum melts at about 918C (about 1684F), boils at about 3464C (about 6267F), and has a specific gravity of 6.15. The atomic weight of lanthanum is 138.91.



Article key phrases:

lanthanide series, misch metal, lanthanum oxide, monazite, fluorspar, metallic element, Lanthanum, rare earth elements, atomic number, periodic table, crust, alloys, specific gravity, minerals, symbol, air, notice, member

 
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