|Name, Symbol, Number||Barium, Ba, 56|
|Series||alkaline earth metals|
|Group, Period, Block||2(IIA), 6, s|
|Density, Hardness||3510 kg/m3, 1.25|
|Atomic weight||137.327 amu|
|Atomic radius (Calc.)||215 pm (253 pm)|
|Covalent radius||198 pm|
|van der Waals radius||no information|
|e- 's per energy level||2, 8, 18, 18, 8, 2|
|Oxidation states (Oxide)||2 (strong base)|
|Crystal structure||Cubic body centered|
|State of matter||solid (paramagnetic)|
|Melting point||1000 K (1341 °F)|
|Boiling point||2143 K (3398 °F)|
|Molar volume||38.16 ×1010-3 m3/mol|
|Heat of vaporization||142 kJ/mol|
|Heat of fusion||7.75 kJ/mol|
|Vapor pressure||98 Pa at 371 K|
|Speed of sound||1620 m/s|
|Specific heat capacity||204 J/(kg*K)|
|Electrical conductivity||3 106/m ohm|
|Thermal conductivity||18.4 W/(m*K)|
|1st ionization potential||502.9 kJ/mol|
|2nd ionization potential||965.2 kJ/mol|
|3rd ionization potential||3600 kJ/mol|
|Most Stable Isotopes|
|SI units & STP are used except where noted.|
|Table of contents|
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Barium is a metallic element that is chemically similar to calcium, yet is soft and in its pure form is silvery white resembling lead.
This metal oxidizes very easily and when exposed to air and is highly reactive with water or alcohol.
Barium is decomposed by water or alcohol. Some of the compounds of this element are remarkable for their high specific gravity, as its sulphate, called heavy spar.
Barium is primarily used in sparkplugs, vacuum tubes, fireworks, and in fluorescent lamps.
- A "getter" in vacuum tubes.
- Barium sulfate is permanent white and is used in paint, in X-ray diagnostic work, and in glassmaking.
- Barite is used extensively as a weighing agent in oil well drilling fluids and in rubber production.
- Barium carbonate is a useful rat poison, while barium nitrate and chlorate give colors in fireworks.
- Impure barium sulfide phosphoresces after exposure to the light.
- Barium salts are sometimes used in medical procedures, such as X-raying the digestive system.
- Lithopone, a pigment that contains barium sulfate and zinc sulfide, has good covering power, and does not darken in when exposed to sulfides.
HistoryBarium (Greek "barys" meaning "heavy") was first identified in 1774 by Carl Scheele and extracted in 1808 by Sir Humphry Davy in England. The oxide was at first called barote, by Guyton de Morveau, which was changed by Antoine Lavoisier to baryta, which soon was modified to "barium" to describe the metal.
OccurrenceBecause 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 sulphate.
Barium is commercially produced through the electrolysis of molten barium chloride (BaCl2) Isolation (* follow):
(cathode) Ba2+* + 2e- ---> Ba (anode) Cl-* --> ½Cl2 (g) + e-
CompoundsThe most important compounds are barium peroxide, chloride, sulfate, carbonate, nitrate, and chlorate. When burned, barium salts glows green. (See "Uses" section above)
IsotopesNaturally occurring barium is a mix of seven stable isotopes. There are twenty-two isotopes known, but most of these are highly radioactive and have half-lifes in the several millisecond to several minute range. The only notable exception is barium-133 which has a half-life of 10.51 years.
PrecautionsAll water or acid soluble barium compounds are extremely poisonous.
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.