Barium

Caesium - Barium - Lanthanum Sr Ba Ra       Full table
General
Name, Symbol, Number	Barium, Ba, 56
Series	alkaline earth metals
Group, Period, Block	2(IIA), 6, s
Density, Hardness	3510 kg/m3, 1.25
Appearance	silvery white
Atomic Properties
Atomic weight	137.327 amu
Atomic radius (Calc.)	215 pm (253 pm)
Covalent radius	198 pm
van der Waals radius	no information
Electron configuration	[Xe]6s2
e- 's per energy level	2, 8, 18, 18, 8, 2
Oxidation states (Oxide)	2 (strong base)
Crystal structure	Cubic body centered
Physical Properties
State of matter	solid (paramagnetic)
Melting point	1000 K (1341 °F)
Boiling point	2143 K (3398 °F)
Molar volume	38.16 ×10-3 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
Miscellaneous
Electronegativity	0.89(Pauling scale)
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
iso NA half-life DM DE MeV DP 130Ba 0.106% Ba is stable with 74 neutrons 132Ba 0.101% Ba is stable with 76 neutrons 133Ba {syn.} 10.51 y epsilon 0.517 133Cs 134Ba 2.417% Ba is stable with 78 neutrons 135Ba 6.592% Ba is stable with 79 neutrons 136Ba 7.854% Ba is stable with 80 neutrons 137Ba 11.23% Ba is stable with 81 neutrons 138Ba 71.7% Ba is stable with 82 neutrons
SI units & STP are used except where noted.

Barium is a chemical element in the periodic table that has the symbol Ba and atomic number 56. A soft silvery metallic element, barium is an alkaline earth metal and melts at a very high temperature. Its oxide is called baryta[?] and it is primarily found in the mineral barite but is never found in its pure form due to its reactivity[?] with air. Compounds of this metal are used in small quantities in paints and in glassmaking.

Table of contents 1 Notable Characteristics 2 Applications 3 History 4 Occurrence 5 Compounds 6 Isotopes 7 Precautions 8 External Links

Notable Characteristics 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. Applications Barium is primarily used in sparkplugs, vacuum tubes, fireworks, and in fluorescent lamps. Also:

• 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.

History Barium (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. 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 sulphate.
Barium is commercially produced through the electrolysis of molten barium chloride[?] (BaCl₂) Isolation (* follow):
(cathode) Ba²⁺* + 2e^- ---> Ba (anode) Cl^-* --> ½Cl₂ (g) + e^- Compounds The most important compounds are barium peroxide[?], chloride[?], sulfate[?], carbonate[?], nitrate[?], and chlorate[?]. When burned, barium salts glows green. (See "Uses" section above) Isotopes 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. Precautions 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.

External Links

• WebElements.com - Barium (http://www.webelements.com/webelements/elements/text/Ba/index)
• EnvironmentalChemistry.com - Barium (http://environmentalchemistry.com/yogi/periodic/Ba)
• Information on barium meal (http://www.cancerhelp.org.uk/help/default.asp?page=1541)

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Barium is also the latin name for the city Bari in Italy.