Abstract

Barium, Ba, is a member of Group 2 (IIA) of the Periodic Table, where it lies between strontium and radium. Along with calcium and strontium, barium is classed as an alkaline~arth metal, and is the densest of the three. Barium metal does not occur free in nature; however, its compounds occur in small but widely distributed amounts in the earth's crust, especially in igneous rocks, sandstone, and shale. The principal barium minerals are barytes (barium sulfate) and witherite (barium carbonate), also known as heavy spar. The latter mineral can be readily decomposed via calcination to form barium oxide, BaO, the ore used commercially for the preparation of barium metal. Barium is prepared commercially by the thermal reduction of barium oxide with aluminum. Barium metal is highly reactive, a property that accounts for its principal uses as a getter for removing residual gases from vacuum systems on cathode ray tubes (eg, in CRT tubes) and as a deoxidizer for steel and other metals. Pure barium is a silvery-white metal, although contamination with nitrogen produces a yellowish color. The metal is relatively soft and ductile and may be worked readily. It is fairly volatile (though less so than magnesium), and this property is used to advantage incommercial production. It is an extremely reactive metal, and its compounds possess large free energies of formation Barium metal and most barium compounds are highly poisonous Barium ions act as a muscle stimulant and can cause death through ventricular fibrillation of the heart. Barium also presents a hydrogen explosion hazard if allowed to come into contact with water or atmospheric moisture, and must always be kept dry and preferably sealed in the shipping containers.