Barium

Barium 1

Sir Humphry Davy, Bt by Sir Thomas Lawrence

Benitoite HD

BariumXray

2006 Fireworks 1

Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2 of the periodic table, a group of elements known as the alkaline earth metals. Barium is a soft, silvery metallic alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. Its hydroxide, known in pre-modern times as baryta, does not occur as a mineral, but can be prepared by heating barium carbonate.

Properties

Barium has a medium density and is a soft metal with a hardness that is slightly higher than that of lead. It is an excellent conductor of electricity but is easily oxidized in air and reacts vigorously with water to form barium hydroxide, Ba(OH)2, and hydrogen gas (H2). This reaction is highly exothermic and releases sufficient heat to ignite the hydrogen gas produced.

Occurrence

The most common minerals of barium are barite (barium sulfate, BaSO4) and witherite (barium carbonate, BaCO3), both insoluble in water. Barite is the principal source of barium and its compounds and is also a significant mineral in the petroleum industry for drilling muds. Witherite is less common but is the main source of barium chemicals that require a high purity.

Applications

Barium has a wide range of applications in the industry. Its compounds are used in paint and glass making, as a part of X-ray contrast agents for imaging the human gastrointestinal tract, and in the manufacture of certain types of rubber. Barium nitrate and chlorate are used in fireworks to provide a green color. Barium titanate is a ferroelectric material used in capacitors, sonar devices, and actuators.

Health Effects

Barium compounds, if not handled properly, can be toxic. Soluble barium compounds, such as barium nitrate, chloride, and hydroxide, can cause muscle paralysis and affect the heart and nervous system. Barium sulfate, due to its insolubility in water, is considered non-toxic and is commonly used as a contrast agent for X-ray imaging and other diagnostic procedures.

Environmental Impact

Barium is released into the environment through the mining, refining, and processing of barium ores and through the burning of coal and oil. The release of barium into the environment can affect terrestrial and aquatic ecosystems. In water, barium can accumulate in fish and other aquatic species, leading to potential health risks to wildlife and humans consuming these species.

See Also

• Alkaline earth metal
• Chemical element
• Periodic table