Barium

Barium (chemical symbol Ba, atomic number 56) is a soft metal with a silvery-white color that oxidizes readily in air. It belongs to the group of alkaline earth metals, which also includes calcium and strontium.

Because of its high reactivity, barium is not found in nature as pure metal. It occurs in mixed minerals, the most common being baryte (barium sulfate) and witherite (barium carbonate). The name comes from a Greek word meaning 'heavy', because baryte mineral is notably dense.

Chemical properties

Barium has two electrons in its outermost shell, which it loses to form the Ba²⁺ ion. It reacts vigorously with water, producing barium hydroxide and hydrogen. Because of this, it is normally stored under oil. When burned, it emits a green light—a property used in flame tests and in the production of colored fireworks.

Uses

Barium sulfate is widely used in the petroleum industry, where it is added to drilling mud for wells to increase density. It is also used in white pigments and in the cement industry. Barium carbonate is sometimes used in the manufacture of glass and rat poison. Other uses include colored flames and certain electronic equipment.

Medical applications

Barium sulfate is used as a contrast agent in X-ray imaging of the chest and abdomen. Patients are given a preparation called 'barium meal' or 'barium enema'. It is chosen because barium sulfate is poorly soluble in water and therefore does not enter the bloodstream persistently. Other barium salts that dissolve in water are poisons and can affect nerve function and heart contraction.