Barium Barium Bromine Category="Alkaline earth metals"Category="Chemical elements"Category="Toxicology"

: Barium is also the Latin name for the city Bari in Italy.

56 Caesium ← barium → Lanthanum
Sr
↑
Ba
↓
Ra
[image]
periodic table
General
Name, Symbol, Number barium, Ba, 56
Chemical series alkaline earth metals
Group, Period, Block 2, 6, s
Appearance silvery white
[image]
Atomic mass 137.327(7) g/mol
Electron configuration [Xe] 6s²
Electrons per shell 2, 8, 18, 18, 8, 2
Physical properties
Phase Solid
Density (near r.t.) 3.51 g/cmł
Liquid Density at m.p. 3.338 g/cmł
Melting point 1000 K
(727 °C, 1341 °F)
Boiling point 2170 K
(1897 °C, 3447 °F)
Heat of fusion 7.12 kJ/mol
Heat of vaporization 140.3 kJ/mol
Heat capacity (25 °C) 28.07 J/(mol·K)

Vapor pressure
P/Pa 1 10 100 1 k 10 k 100 k
at T/K 911 1038 1185 1388 1686 2170
Atomic properties
Crystal structure cubic body centered
Oxidation states 2
(strongly basic oxide)
Electronegativity 0.89 (Pauling scale)
Ionization energies 1st: 502.9 kJ/mol
2nd: 965.2 kJ/mol
3rd: 3600 kJ/mol
Atomic radius 215 pm
Atomic radius (calc.) 253 pm
Covalent radius 198 pm
Miscellaneous
Magnetic ordering paramagnetic
Electrical resistivity (20 °C) 332 nΩ·m
Thermal conductivity (300 K) 18.4W/(m·K)
Thermal expansion (25 °C) 20.6 µm/(m·K)
Speed of sound (thin rod) (20 °C) 1620 m/s
Young's modulus 13 GPa
Shear modulus 4.9 GPa
Bulk modulus 9.6 GPa
Mohs hardness 1.25
CAS registry number 7440-39-3
Notable isotopes

Main article: Isotopes of barium
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 ε 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
References

Barium is a toxic 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.

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 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 is its Sulfate: Barite Ba(SO₄) also 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 and can also be used in making glass and bricks, while Barium nitrate and chlorate give green colors in fireworks.
Impure barium sulfide phosphoresces after exposure to the Light.
Barium salts, especially Barium sulfate, are sometimes given orally (a Barium meal) or as an Enema, to increase the contrast of medical X-rays of 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 sulfate. Barium is commercially produced through the Electrolysis of molten Barium chloride (BaCl₂) Isolation (* follow):

: (Cathode) Ba²⁺* + 2e^- → Ba (Anode) Cl^-* → ˝Cl₂ (g) + e^-

Compounds

The most important compounds are barium peroxide, chloride, sulfate, carbonate, nitrate, and chlorate. When burned, barium salts glows green.

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. Barium sulfate can be used in medicine only because it does not dissolve, and is eliminated completely from the digestive tract.

External links

WebElements.com - Barium
Information on barium meal