Barium (Ba), chemical element, one of the alkaline-earth metals of Group 2 (IIa) of the periodic table. The element is used in metallurgy, and its compounds are used in pyrotechnics, petroleum production, and radiology. Barium, which is slightly harder than lead, has a silvery white lustre when freshly cut. It readily oxidizes when exposed to air and must be protected from oxygen during storage. Continue reading from Encyclopedia Britannica
In the early 1600s, Vincenzo Casciarolo, of Bologna, Italy, found some unusual pebbles. If they were heated to redness during the day, they would shine during the night. This was the mineral barite (barium sulfate, BaSO4).
When Bologna stone, as it became known, was investigated by Carl Scheele in 1760s he realised it was the sulfate of an unknown element. Meanwhile a mineralogist, Dr William Withering, had found another curiously heavy mineral in a lead mine in Cumberland which clearly was not a lead ore. He named it witherite; it was later shown to be barium carbonate, BaCO3. Neither the sulfate nor the carbonate yielded up the metal itself using the conventional process of smelting with carbon. However, Humphry Davy at the Royal Institution in London produced it by the electrolysis of barium hydroxide in 1808. Continue reading from Royal Society of Chemistry
Barium is found naturally only in combination with other elements because of its high level of reactivity. Barium is most commonly found combined with sulfate and carbonate, but can also form compounds with hydroxide, chloride, nitrate, chlorate, and other negative ions.
Elemental barium does not have many practical uses, again due to its high level of reactivity. However, its strong attraction to oxygen makes it useful as a "getter" to remove the last traces of air in vacuum tubes. Compounds containing barium have a variety of commercial uses. Barium sulfate, or barite, is used in lithopone (a brightening pigment in printer paper and paint), oil well drilling fluids, glassmaking and creating rubber. Continue reading from LiveScience
