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Barium was first isolated in 1808 by English chemist Sir Humphry Davy (1778-1829). In 1807 and 1808, Davy also discovered five other new elements: sodium, potassium, strontium, calcium, and magnesium. All of these elements had been recognized much earlier as new substances, but Davy was the first to prepare them in pure form. (See sidebar on Davy in the Calcium entry.)
Barium had first been identified as a new material in 1774 by Swedish chemist Carl Wilhelm Scheele (1742-86). The form with which Scheele worked, however, was a compound of barium, barium sulfate (BaSO4). Barium sulfate is, in fact, the most common naturally occurring ore of barium. It is generally known as barite or barytes.
Barium is a member of the alkaline earth metals. The alkaline earth metals make up Group 2 (IIA) of the periodic table. The other elements in this group are beryllium, magnesium, calcium, strontium, and radium. These elements tend to be relatively active chemically and form a number of important and useful compounds. They also tend to occur abundantly in the Earth's crust in a number of familiar minerals such as aragonite, calcite, chalk, Limestone, marble, travertine, magnesite, and dolomite.
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