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...