Barium

Barium,₀₀Ba

Barium
Pronunciation	/ˈbɛəriəm/​(BAIR-ee-əm)
Appearance	silvery gray; with a pale yellow tint
Standard atomic weightAr°(Ba)
	137.327(7)
Barium in theperiodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Sr ↑ Ba ↓ Ra caesium←barium→lanthanum
Group	group 2 (alkaline earth metals)
Period	period 6
Block	s-block
Electron configuration	[Xe] 6s2
Electrons per shell	2, 8, 18, 18, 8, 2
Physical properties
PhaseatSTP	solid
Melting point	1000K​(727 °C, ​1341 °F)
Boiling point	2118 K ​(1845 °C, ​3353 °F)
Density(nearr.t.)	3.51 g/cm3
when liquid (atm.p.)	3.338 g/cm3
Heat of fusion	7.12kJ/mol
Heat of vaporization	142 kJ/mol
Molar heat capacity	28.07 J/(mol·K)
Vapor pressure P(Pa) 1 10 100 1 k 10 k 100 k atT(K) 911 1038 1185 1388 1686 2170
Atomic properties
Oxidation states	+1,+2(a stronglybasicoxide)
Electronegativity	Pauling scale: 0.89
Ionization energies	1st: 502.9 kJ/mol 2nd: 965.2 kJ/mol 3rd: 3600 kJ/mol
Atomic radius	empirical: 222pm
Covalent radius	215±11 pm
Van der Waals radius	268 pm
Spectral linesof barium
Other properties
Natural occurrence	primordial
Crystal structure	​body-centered cubic(bcc)
Speed of soundthin rod	1620 m/s (at 20 °C)
Thermal expansion	20.6 µm/(m⋅K) (at 25 °C)
Thermal conductivity	18.4 W/(m⋅K)
Electrical resistivity	332 nΩ⋅m (at 20 °C)
Magnetic ordering	paramagnetic
Molar magnetic susceptibility	+20.6·10−6cm3/mol
Young's modulus	13 GPa
Shear modulus	4.9 GPa
Bulk modulus	9.6 GPa
Mohs hardness	1.25
CAS Number	7440-39-3
History
Discovery	Carl Wilhelm Scheele(1772)
First isolation	Humphry Davy(1808)
Isotopes of barium
Main isotopes Decay abun­dance half-life(t1/2) mode pro­duct 130Ba 0.11% (0.5–2.7)×1021y εε 130Xe 132Ba 0.1% stable 133Ba synth 10.51 y ε 133Cs 134Ba 2.42% stable 135Ba 6.59% stable 136Ba 7.85% stable 137Ba 11.2% stable 138Ba 71.7% stable

Corroded barium metal

Bariumischemical element56 on theperiodic table.Its symbol isBa.It contains 56protonsand 56electrons.Its mass number is about 137.3. It is ametal.

Properties

Physical properties

Barium is part of a group of elements known as thealkaline earth metals.It is a silvery metal that easily turns black. It is soft andductile.It can formalloyswith some metals that are partially alloys and partiallychemical compounds.

Chemical properties

Barium is reactive, and if you put pure barium metal in the air, it will react withoxygen.At first it will turn black, then white asbarium oxideis formed. Barium reacts with water to makebarium hydroxideandhydrogen gas.Barium also reacts very fast withacidsto make a barium salt and hydrogen. Barium can formbarium peroxideif it is burned in air.

Barium reacts with many other metal oxides and sulfides to make barium oxide or sulfide and the metal. It also reacts with carbon and nitrogen at a high temperature to make barium cyanide.

Chemical compounds

See also:Category:Barium compounds

Barium is too reactive as a metal, so it is not found in the earth as a metal. It is found in chemical compounds. Barium only occurs in oneoxidation state:+2. Most barium compounds are colorless. The ones that dissolve in water or stomach acid are very toxic.Barium sulfateis well known because it does not dissolve in water or acids. Barium compounds are quite heavy. Barium compounds put out a greenish flame when heated red-hot.

• 
  Barium chloride
• 
  Barium sulfate

Occurrence

Barium sulfate as barite

Barium is found asbarium sulfate(barite) andbarium carbonate(witherite) in the ground. Both of thesemineralsdo not dissolve in water. Barium sulfate hardly dissolves in anything. Barium is found mainly inChina,Germany,India,Morocco,and theUS.

Preparation

It is very hard to get barium from barium sulfate. So barium sulfate isreducedbycarbonto makebarium sulfideandcarbon dioxide.The barium sulfide is dissolved inhydrochloric acid.This makeshydrogen sulfideand barium chloride. The barium chloride is melted andelectrolyzedto get liquid barium metal. The barium metal is solidified and stored in oil.

Barium carbonate, the other ore of barium, is dissolved inhydrochloric acidto make barium chloride and carbon dioxide. The barium chloride is melted and electrolyzed, making barium metal.

Uses

As a metal

Barium is used to remove oxygen fromcathode ray tubesandvacuum tubes.It is placed inside and reacts with all of the oxygen, using it up. Barium is also used inspark plugwire.

As chemical compounds

Certaincompoundsof barium, such asbarium sulfate,are not toxic and can be put in the body. We can see where the barium travels in the body byX-raysand this can tell us whether there are problems, such as blockages. The barium sulfate builds up inside the body accumulating in organ systems. Barium sulfate absorbs the X-Rays as they pass through the body and an image is formed from the points where the rays have not passed through. It is useful because it provides a reasonably detailed image from very limited radiation exposure, compared with a CT scan for instance. Barium sulfate can be used as a pigment, too.

Other barium compounds have several other uses.

Safety

Barium is a verytoxicelement, and is dangerous. There is a really small amount of barium in ourfood,and this does not cause problems. If we get barium from other places, though, it can cause many problems. Even 1 gram of barium can kill you. It is dangerous because it acts like other really important elements, such ascalciumandmagnesium.If barium replaces these elements, it messes up the body.