Essay by Anonymous UserHigh School, 10th gradeA+, December 1997

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Dmitrii Ivanovich Mendelev predicts the existance and properties of the element

after zinc in the periodic table. He Gives it the name 'eka aluminium'.


Paul Emile Lecoq de Boisbaudran discovers gallium.

Its properties closely match those predicted by Mendelev.

Gallium, atomic number 31, is very similar to aluminum in its chemical

properties. It does not dissolve in nitric acid because of the protective film of

gallium 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, who observed

its principal spectral lines while examining material seperated from zinc blende.

Soon after he isolated the metal studied its properties, which coincided those that

Dmitrii Ivanovich Mendelev had predicted a few years earlier for eka-aluminium, the

then undiscovered element lying between aluminum and indium in his periodic table.

Though widely distributed at the Earth's surface, gallium does not occor

free or concentrated in independant minerals, except for gallite. It is extracted as

a by-product from zinc blende, iron pyrites, bauxite, and germanite.

Silvery white and soft enough to be cut with a knife, gallium takes on a bluish

tinge because of superficial oxidation. Unusual for its low melting point

( about 30 degrees C, 86 degrees F ), gallium also expands upon solidification and

supercools readily, remaining a liquid at temperatures as low as 0 degrees C ( 32 degrees F ).

Gallium has the longest usefull liquid range of any element. The liquid metal

clings to glass and similar surfaces. The crystal structure of gallium is orthorhombic.

Natural gallium consists of a mixture of two stable isotopes: gallium-69 ( 60.4 percent )

and gallium-71 (39.6 percent ).

Somewhat similar to aluminum chemically, gallium slowly oxidizes in moist...