Barium is a metal element with an atomic number of 56. It has an atomic symbol of Ba, and its atomic weight is 137.327. Like other metals, barium is a good conductor of heat and electricity. It is silvery white and relatively malleable. Chemically, it resembles calcium and strontium, which are fellow members of the alkaline-earth family of metals. The metal gets its name from the Greek word for "heavy," barys, which was first used to name the mineral barite, or heavy spar. Barium has seven stable isotopes.

During the 1700s, chemists thought that barium oxide and calcium oxide were the same substance. In 1774, Carl Wilhelm Scheele showed that barium oxide is a distinct compound, pointing the way toward discovery of the element. In the early 1800s, after electric batteries had been invented, chemists began using electric currents to break compounds apart. Humphry Davy, who pioneered this technique of electrolysis...