|
|
Atomic Number: |
56 |
Melting Point: | 727 ºC | |
| Atomic Symbol: | Ba | Boiling Point: | 1897 ºC | ||
| Atomic Weight: | 137.3 amu | Density: | 3510
kg/m 3 |
||
| Atomic Radius: |
217.3 pm |
Oxidation States: | 2 | ||
| Covalent Radius: | 198 pm | Electron Configuration: | [Xe]6s2 | ||
| van der Waals Radius: |
-- |
State of Matter: | solid (paramagnetic) |
(Gr. barys: heavy) Baryta was distinguished from lime by Scheele in 1774; the element was discovered by Sir Humphrey Davy in 1808.
Barium is a metallic element, soft, and when pure is silvery white; it belongs to the alkaline earth group, chemically resembling calcium . 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 most important compounds are barium peroxide, chloride, sulfate, carbonate, nitrate, and chlorate. When burned, barium salts glows green.
Barium is found only in combination with other elements, chiefly with sulfate and carbonate and is prepared by electrolysis of the chloride.
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 oil well 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 pyrotechnics. 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.
Naturally 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.
All 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.
