Gallium :: essays research papers

atomic number 311871 Dmitrii Ivanovich Mendelev predicts the existance and properties of theelement after zinc in the periodic table. He Gives it the name "eka aluminium".1875 Paul Emile Lecoq de Boisbaudran discovers atomic number 31. Its properties fastmatch those predicted by Mendelev.     Gallium, atomic number 31, is very similar to aluminum in its chemicalproperties. It does not dissolve in nitric acid because of the cautionary filmof tabun oxide that is formed over the surface by the action of the acid.Gallium does however dissolve in other acids, and alkalies.     Gallium was discovered (1875) by Paul Emile Lecoq de Boisbaudran, whoobserved its principal spectral lines while examining material seperated fromzinc blende. Soon after he isolated the metal studied its properties, whichcoincided those that Dmitrii Ivanovich Mendelev had predicted a few yearsearlier for eka-aluminium, the then undiscovered element lying between al uminumand indium in his periodic table.     Though widely distributed at the Earths surface, gallium does not occorfree or concentrated in independant minerals, except for gallite. It isextracted as a by-product from zinc blende, iron pyrites, bauxite, andgermanite.     Silvery white and soft rich to be cut with a knife, gallium takes on abluish tinge because of superficial oxidation. Unusual for its low meltingpoint ( about 30 degrees C, 86 degrees F ), gallium also expands uponsolidification and supercools readily, remaining a liquid at temperatures aslow as 0 degrees C ( 32 degrees F ).     Gallium has the longest usefull liquid range of any element. The liquidmetal clings to glass and similar surfaces. The crystal structure of galliumis orthorhombic. Natural gallium consists of a mixture of two stable isotopesgallium-69 ( 60.4 percent ) and gallium-71 (39.6 percent ).     Somewhat similar to aluminu m chemically, gallium slowly oxidizes inmoist air until a protective film forms, and it becomes passive in cold nitricacid.     Gallium has been considered as a possible heat-exchange medium innuclear reactors, although it has a high school neutron cross section. Radioactivegallium-72 shows some promise in the study of bone cancer a compound of thisisotope is absorbed by the cancerous portion of the bone.     The virtually common use of gallium is in a gallium scan. Gallium scans areoften used to diagnose and follow the progression of tumors or infections.Gallium scans can also be used to evaluate the heart, lungs, or any other organthat may be involved with inflammatory disease.