1s² 2s²p⁶ 3s²p⁶d¹⁰ 4s²p⁶d¹⁰ 5s²p⁶ 6s²

Characteristics

Barium is a metallic element that is chemically similar to Calcium but more reactive.  This metal oxidizes very easily when exposed to air and is highly reactive with water or alcohol, producing Hydrogen Gas, H2.  Burning in air or Oxygen produces not just Barium Oxide (BaO) but also the Peroxide.

  Simple compounds of this heavy element are notable for their high specific gravity.  This is true of the most common Barium-bearing mineral, its Sulfate Barite, BaSO₄, also called 'heavy spar' due to the high density (4.5 g/cm³).

Occurrence

Because barium quickly becomes oxidized in air, it is difficult to obtain this metal in its pure form.  It is primarily found in and extracted from the mineral Barite which is crystalized Barium Sulfate.  Barium is commercially produced through the electrolysis of molten Barium Chloride, BaCl):

(Cathode) Ba²⁺ + 2e^- Ba (Anode) Cl^- ½Cl₂ (g) + e^-

Applications

Barium has some medical and many industrial uses:

• Barium compounds, and especially Barite, BaSO₄, are extremely important to the petroleum industry.  Barite is used in drilling mud, a weighting agent in drilling new oil wells.
• Barium Sulfate, BaSO₄,  is also a good X-ray absorber, used in X-ray diagnostic work for obtaining images of the digestive system ("Barium meals" and Barium enemas").
• Barium Carbonate, BaCO₃, is a useful rat poison and can also be used in making bricks.  Unlike the Sulfate, the Carbonate disolves in stomach acid, allowing it to be poisonous.
• An alloy with Nickel is used in sparkplug wire.
• Barium Oxide, BaO, is used in a coating for the electrodes of fluorescent lamps, which facilitates the release of electrons.
• The metal is a "getter" in vacuum tubes, to remove the last traces of Oxygen.
• Barium Carbonate is used in glassmaking.  Being a heavy element, Barium increases the refractive index and luster of the glass.
• Barite is used extensively in rubber production.
• Barium Nitrate, BaNO₃, and Barium Chlorate, BaClO₃,    give green colors in fireworks.
• Impure Barium Sulfide phosphoresces after exposure to the light.
• Lithopone, a pigment that contains Barium Sulfate and Zinc Sulfide, is a permanent white that has good covering power, and does not darken in when exposed to sulfides.
• Barium Peroxide, BaO₂, can be used as a catalyst to start an Aluminothermic Reaction when welding rail tracks together.  It can also be used in green tracer ammunition.
• Barium Titanate, BaTiO₃, is used as a dielectric material in capacitors.
• Barium Ferrite, BaO·6Fe₂O₃, is used to make magnets.

Compounds

The most important compounds are:

Isotopes

Naturally occurring Barium is a mix of seven stable isotopes.  There are thirty-three isotopes known, but most of these are highly radioactive and have half-lifes in the several millisecond to several minute range.  The only notable exceptions are ¹³³Ba which has a half-life of 10.51 years, and ^137mBa (2.55 minutes).

Precautions

All water or acid soluble Barium compounds are extremely poisonous.   At low doses, Barium acts as a muscle stimulant, while higher doses affect the nervous system, causing cardiac irregularities, tremors, weakness, anxiety, dyspnea and paralysis.

This may be due to its ability to block Potassium Ion channels which are critical to the proper function of the nervous system.

Barium Sulfate can be used in medicine only because it does not dissolve, and is eliminated completely from the digestive tract. Unlike other heavy metals, Barium does not bioaccumulate.  However, inhaled Barium dust can accumulate in the lungs, a benign condition called baritosis.

Oxidation occurs very easily and, to remain pure, barium should be kept under a petroleum-based fluid (such as kerosene) or other suitable Oxygen-free liquids that exclude air.

(Gr. barys, heavy) Baryta was distinguished from lime by Scheele in 1774; the element was discovered by Sir Humphrey Davy in 1808. It is found only in combination with other elements, chiefly with sulfate and carbonate and is prepared by electrolysis of the chloride. Barium is a metallic element, soft, and when pure is silvery white like lead; it belongs to the alkaline earth group, resembling calcium chemically. The metal oxidizes very easily and should be kept under petroleum or other suitable oxygen-free liquids to exclude air. It is decomposed by water or alcohol. The metal is used as a "getter" in vacuum tubes. The most important compounds are the peroxide, chloride, sulfate, carbonate, nitrate, and chlorate. Lithopone, a pigment containing barium sulfate and zinc sulfide, has good covering power, and does not darken in the presence of sulfides. The sulfate, as permanent white is also used in paint, in X-ray diagnostic work, and in glassmaking. Barite is extensively used as a weighing agent in oilwell drilling fluids, and is used in making rubber. The carbonate has been used as a rat poison, while the nitrate and chlorate give colors in pyrotechny. The impure sulfide phosphoresces after exposure to the light. All barium compounds that are water or acid soluble are poisonous. Naturally occurring barium is a mixture of seven stable isotopes. Twenty two other radioactive isotopes are known to exist.

Source: CRC Handbook of Chemistry and Physics, 1913-1995. David R. Lide, Editor in Chief. Author: C.R. Hammond

Barium was first isolated by Sir Humphry Davy, an English chemist, in 1808 through the electrolysis of molten baryta (BaO). Barium is never found free in nature since it reacts with oxygen in the air, forming barium oxide (BaO), and with water, forming barium hydroxide (Ba(OH)₂) and hydrogen gas (H₂). Barium is most commonly found as the mineral barite (BaSO₄) and witherite (BaCO₃) and is primarily produced through the electrolysis of barium chloride (BaCl₂).

Barium is used as a getter, a material that combines with and removes trace gases from vacuum tubes.

Barium sulfate (BaSO₄), a common barium compound, is used as a filler for rubber, plastics and resins. It can be combined with zinc oxide (ZnO) to make a white pigment known as lithophone or with sodium sulfate (Na₂SO₄) to make another white pigment known as blanc fixe. Stones made from impure barium sulfate glow when exposed to light and will glow in the dark for up to six years if intensely heated in the presence of charcoal. These stones, known as Bologna stones, were discovered near Bologna, Italy in the early 1500s and were thought to possess magical properties by alchemists. Although all barium compounds are poisonous, barium sulfate can be safely ingested since it does not dissolve in water. It is also a good absorber of X-rays and, when swallowed, can be used to produce X-ray images of the intestinal tract.

Barium carbonate (BaCO₃), another common barium compound, is used in the manufacture of ceramics and some types of glass. It is a component in clay slurries used in drilling oil wells. Barium carbonate is used to purify some chemical solutions and is the primary base material for the manufacture of other barium compounds.

Barium forms several other useful compounds. Barium nitrate (Ba(NO₃)₂) burns with a bright green color and is used in signal flares and fireworks. Barium chloride (BaCl) is used as a water softener. Barium oxide (BaO) easily absorbs moisture and is used as a desiccant. Barium peroxide (BaO₂) forms hydrogen peroxide (H₂O₂) when it is mixed with water and is used as a bleaching agent that activates when wet. Barium titanate (BaTiO₃) is used as a dielectric material in capacitors. Barium ferrite (BaO·6Fe₂O₃) is used to make magnets.