For the Chinese hacker group, see Double Dragon (hacking group).
Not to be confused with Baryon.
Chemical element, symbol Ba and atomic number 56
Barium, 56Ba
Barium
Pronunciation
/ˈbɛəriəm/(BAIR-ee-əm)
Appearance
silvery gray; with a pale yellow tint[1]
Standard atomic weight Ar°(Ba)
137.327±0.007[2]
137.33±0.01 (abridged)[3]
Barium in the periodic 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
Atomic number (Z)
56
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
Phase at STP
solid
Melting point
1000 K (727 °C, 1341 °F)
Boiling point
2118 K (1845 °C, 3353 °F)
Density (at 20° C)
3.594 g/cm3[4]
when liquid (at m.p.)
3.338 g/cm3
Heat of fusion
7.12 kJ/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
at T(K)
911
1038
1185
1388
1686
2170
Atomic properties
Oxidation states
+1, +2 (a strongly basic oxide)
Electronegativity
Pauling scale: 0.89
Ionization energies
1st: 502.9 kJ/mol
2nd: 965.2 kJ/mol
3rd: 3600 kJ/mol
Atomic radius
empirical: 222 pm
Covalent radius
215±11 pm
Van der Waals radius
268 pm
Spectral lines of barium
Other properties
Natural occurrence
primordial
Crystal structure
body-centered cubic (bcc) (cI2)
Lattice constant
a = 502.5 pm (at 20 °C)[4]
Thermal expansion
20.47×10−6/K (at 20 °C)[4]
Thermal conductivity
18.4 W/(m⋅K)
Electrical resistivity
332 nΩ⋅m (at 20 °C)
Magnetic ordering
paramagnetic[5]
Molar magnetic susceptibility
+20.6×10−6 cm3/mol[6]
Young's modulus
13 GPa
Shear modulus
4.9 GPa
Bulk modulus
9.6 GPa
Speed of sound thin rod
1620 m/s (at 20 °C)
Mohs hardness
1.25
CAS Number
7440-39-3
History
Discovery
Carl Wilhelm Scheele (1772)
First isolation
Humphry Davy (1808)
Isotopes of barium
v
e
Main isotopes[7]
Decay
abundance
half-life (t1/2)
mode
product
130Ba
0.11%
(0.5–2.7)×1021 y
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
Category: Barium
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Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element.
The most common minerals of barium are barite (barium sulfate, BaSO4) and witherite (barium carbonate, BaCO3). The name barium originates from the alchemical derivative "baryta", from Greek βαρὺς (barys), meaning 'heavy'. Baric is the adjectival form of barium. Barium was identified as a new element in 1772, but not reduced to a metal until 1808 with the advent of electrolysis.
Barium has few industrial applications. Historically, it was used as a getter for vacuum tubes and in oxide form as the emissive coating on indirectly heated cathodes. It is a component of YBCO (high-temperature superconductors) and electroceramics, and is added to steel and cast iron to reduce the size of carbon grains within the microstructure. Barium compounds are added to fireworks to impart a green color. Barium sulfate is used as an insoluble additive to oil well drilling fluid. In a purer form it is used as X-ray radiocontrast agents for imaging the human gastrointestinal tract. Water-soluble barium compounds are poisonous and have been used as rodenticides.
^Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 112. ISBN 978-0-08-037941-8.
^"Standard Atomic Weights: Barium". CIAAW. 1985.
^Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
^ abcArblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
^Lide, D. R., ed. (2005). "Magnetic susceptibility of the elements and inorganic compounds". CRC Handbook of Chemistry and Physics(PDF) (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
^Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
^Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
reactivity, barium is never found in nature as a free element. The most common minerals of barium are barite (barium sulfate, BaSO4) and witherite (barium carbonate...
Barium sulfate (or sulphate) is the inorganic compound with the chemical formula BaSO4. It is a white crystalline solid that is odorless and insoluble...
Barium chloride is an inorganic compound with the formula BaCl2. It is one of the most common water-soluble salts of barium. Like most other water-soluble...
higher than that of barium, again confirming periodic trends; the radium-barium density ratio is comparable to the radium-barium atomic mass ratio, due...
Naturally occurring barium (56Ba) is a mix of six stable isotopes and one very long-lived radioactive primordial isotope, barium-130, identified as being...
An upper gastrointestinal series, also called a barium swallow, barium study, or barium meal, is a series of radiographs used to examine the gastrointestinal...
compounds of barium. This white granular monohydrate is the usual commercial form. Barium hydroxide can be prepared by dissolving barium oxide (BaO) in...
They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). The elements have very similar properties: they are...
Barium chromate, is a yellow sand like powder with the formula BaCrO4. It is a known oxidizing agent and produces a green flame when heated, a result of...
Barium nitrate is the inorganic compound with the chemical formula Ba(NO3)2. It, like most barium salts, is colorless, toxic, and water-soluble. It burns...
Barium titanate (BTO) is an inorganic compound with chemical formula BaTiO3. Barium titanate appears white as a powder and is transparent when prepared...
Barium borate is an inorganic compound, a borate of barium with a chemical formula BaB2O4 or Ba(BO2)2. It is available as a hydrate or dehydrated form...
commercial sense, it is one of the most important barium compounds. Barium carbonate is made commercially from barium sulfide by treatment with sodium carbonate...
Barium oxide, also known as baria, is a white hygroscopic non-flammable compound with the formula BaO. It has a cubic structure and is used in cathode...
Barium nitrite is a chemical compound, the nitrous acid salt of barium. It has the chemical formula Ba(NO2)2. It is a water-soluble yellow powder. It is...
Barium acetate (Ba(C2H3O2)2) is the salt of barium(II) and acetic acid. Barium acetate is toxic to humans, but it has use in chemistry and manufacturing...
Barium peroxide is an inorganic compound with the formula BaO2. This white solid (gray when impure) is one of the most common inorganic peroxides, and...
Barium sulfate suspension, often simply called barium, is a contrast agent used during X-rays. Specifically it is used to improve visualization of the...
Barium bromide is the chemical compound with the formula BaBr2. It is ionic and hygroscopic in nature. BaBr2 crystallizes in the lead chloride (cotunnite)...
fluoroscopy. Radiocontrast agents are typically iodine, or more rarely barium sulfate. The contrast agents absorb external X-rays, resulting in decreased...
Barium stars are spectral class G to K stars whose spectra indicate an overabundance of s-process elements by the presence of singly ionized barium, Ba...
mineral consisting of barium sulfate (BaSO4). Baryte is generally white or colorless, and is the main source of the element barium. The baryte group consists...
Bari (/ˈbɑːri/ BAR-ee, Italian: [ˈbaːri] ; Barese: Bare [ˈbæːrə]; Latin: Barium) is the capital city of the Metropolitan City of Bari and of the Apulia...
Barium ferrate is the chemical compound of formula BaFeO4. This is a rare compound containing iron in the +6 oxidation state. The ferrate(VI) ion has two...
did not invent the technique. The actual method (usually referred to as a barium meal test in espionage circles) has been used by intelligence agencies for...
Barium chlorate, Ba(ClO3)2, is the barium salt of chloric acid. It is a white crystalline solid, and like all soluble barium compounds, irritant and toxic...
Barium cyanide is a chemical compound with the formula Ba(CN)2. It is synthesized by the reaction of hydrogen cyanide and barium hydroxide in water or...
Barium iodide is an inorganic compound with the formula BaI2. The compound exists as an anhydrous and a hydrate (BaI2(H2O)2), both of which are white solids...
Yttrium barium copper oxide (YBCO) is a family of crystalline chemical compounds that display high-temperature superconductivity; it includes the first...