Gallium elemental properties

C21-0043. From Its position in the periodic table, predict the properties of gallium (Element 31). 

In 1874 the Erench chemist Paul-Emile Lecoq de Boisbaudran found two previously unidentified lines in the atomic spectrum of a sample of sphalerite (a zinc sulfide, ZnS, mineral). Realizing he was on the verge of a discovery, Lecoq de Boisbaudran quickly prepared a large batch of the zinc mineral, from which he isolated a gram of a new element. He called this new element gallium. The properties of gallium were remarkably close to those Mendeleev predicted for eka-aluminum. 

Gallium [7440-55-3] atomic number 31, was discovered through a study of its spectral properties in 1875 by P. E. Lecoq de Boisbaudran and named from Gallia in honor of its discoverer s homeland. The first element to be discovered after the pubHcation of Mendeleev s Periodic Table, its discovery constituted a confirmation of the Table which was reinforced shordy after by the discoveries of scandium and germanium. 

The person whose name is most closely associated with the periodic table is Dmitri Mendeleev (1836-1907), a Russian chemist. In writing a textbook of general chemistry, Mendeleev devoted separate chapters to families of elements with similar properties, including the alkali metals, the alkaline earth metals, and the halogens. Reflecting on the properties of these and other elements, he proposed in 1869 a primitive version of today s periodic table. Mendeleev shrewdly left empty spaces in his table for new elements yet to be discovered. Indeed, he predicted detailed properties for three such elements (scandium, gallium, and germanium). By 1886 all of these elements had been discovered and found to have properties very similar to those he had predicted. 

After spending considerable time perusing the crumbling pages of late nineteenth-century chemistry journals and textbooks, I have confirmed the traditional account Mendeleev s periodic law attracted little attention. . . until chemists started to discover some of the elements needed to fill the gaps in his table and found that their properties were remarkably similar to those he had predicted. The frequency with which the periodic law was mentioned in-journals increased sharply after the discovery of gallium, most of that increase was clearly associated with Mendeleev s prediction of the properties of the new element, (p, 617)20... 

Mendeleev also predicted the existence of elements that had not yet been discovered. His arrangement of the then-known elements left some obvious holes in the periodic table. For instance, between zinc (combines with 2 Cl) and arsenic (combines with 5 Cl) were holes for one element that would combine with three chlorine atoms and another that would combine with four. Mendeleev assigned these holes to two new elements. He predicted that one element would have a molar mass of 68 g/mol and chemical properties like those of aluminum, while the other would have a molar mass of 72 g /mol and chemical properties similar to silicon. These elements, gallium (Z = 31, M M = 69.7 g/mol) and germanium (Z = 32, M M — 72.6 g/mol), were discovered within 15 years. Chemists soon verified that gallium resembles aluminum in its chemishy, while germanium resembles silicon, just as Mendeleev had predicted. 

The predictions made by Mendeleev provide an excellent example of how a scientific theory allows far-reaching predictions of as-yet-undiscovered phenomena. Today s chemists still use the periodic table as a predictive tool. For example, modem semiconductor materials such as gallium arsenide were developed in part by predicting that elements in the appropriate rows and columns of the periodic table should have the desired properties. At present, scientists seeking to develop new superconducting materials rely on the periodic table to identify elements that are most likely to confer superconductivity. 

Gallium - the atomic number is 31 and the chemical symbol is Ga. The name derives from the Latin gallia for France or perhaps from the Latin gallus for le coq or cock , since it was discovered in zinc blende by the French chemist Paul-Emile Lecoq de Boisbaudan in 1875. It was first isolated in 1878 by Lecoq de Boisbaudran and the French chemist Emile-Clement Jungflesch. This element had previously been predicted as eka-aluminum by Mendeleev, along with its properties and its location in the Periodic Table. 

The discovery of gallium was followed by the discovery of scandium (Mendeleev s eka-boron) in 1879 and of germanium (eka-sili-con) in 1886. The new elements had the approximate atomic weights and properties that Mendeleev had predicted. The scientific world was astonished. It is probably safe to say that before Mendeleev s predictions were confirmed, no chemist would have believed that the properties of unknown elements could be predicted with such accuracy. 

Elemental composition Ga 69.24%, P 30.76%. Gallium phosphide may be characterized hy its physical and electronic properties. It may also he analyzed hy various x-ray methods. Gallium may he measured hy AA and ICP spectrophotometry following digestion with nitric acid or aqua regia and appropriate dilution (See Gallium). 

Metallotropic rearrangement, in mercury tri-azenide complexes, 30 41 Metals, see also Heterobimetallics specific element Transition metal complex alkoxides, 15 159-297 of actinides, 15 290-293 of alkali metals, 15 260-263 of alkaline earths, 15 264-266 of aluminium, 15 266-272 of beryllium, 15 264-266 double type, 15 293-294 of gallium, 15 266-272 of lanthanides, 15 290-293 of magnesium, 15 264-266 properties of, 15 260 of transition metals, 15 272-290 trialkylsilyloxides, 15 295-297 of zinc, 15 264-266... 

Three of the undiscovered elements whose properties Mendeleev foretold in great detail, ekaaluminum, ekaboron, and ekasilicon, were discovered within fifteen years from the time of their prediction. The first was found by Lecoq de Boisbaudran m France, the second by Lars Frednk Nilson in Sweden, and the third by Clemens Winkler in Germany. These elements were named gallium, scandium, and germanium in honor of these countries. 

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