Barium

  • barium, 56ba
    barium unter argon schutzgas atmosphäre.jpg
    barium
    pronunciationm/ (bair-ee-əm)
    appearancesilvery gray; with a pale yellow tint[1]
    standard atomic weight ar, std(ba)137.327(7)[2]
    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
    caesiumbariumlanthanum
    atomic number (z)56
    groupgroup 2 (alkaline earth metals)
    periodperiod 6
    blocks-block
    element category  alkaline earth metal
    electron configuration[xe] 6s2
    electrons per shell2, 8, 18, 18, 8, 2
    physical properties
    phase at stpsolid
    melting point1000 k ​(727 °c, ​1341 °f)
    boiling point2118 k ​(1845 °c, ​3353 °f)
    density (near r.t.)3.51 g/cm3
    when liquid (at m.p.)3.338 g/cm3
    heat of fusion7.12 kj/mol
    heat of vaporization142 kj/mol
    molar heat capacity28.07 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)
    electronegativitypauling scale: 0.89
    ionization energies
    • 1st: 502.9 kj/mol
    • 2nd: 965.2 kj/mol
    • 3rd: 3600 kj/mol
    atomic radiusempirical: 222 pm
    covalent radius215±11 pm
    van der waals radius268 pm
    color lines in a spectral range
    spectral lines of barium
    other properties
    natural occurrenceprimordial
    crystal structurebody-centered cubic (bcc)
    body-centered cubic crystal structure for barium
    speed of sound thin rod1620 m/s (at 20 °c)
    thermal expansion20.6 µm/(m·k) (at 25 °c)
    thermal conductivity18.4 w/(m·k)
    electrical resistivity332 nΩ·m (at 20 °c)
    magnetic orderingparamagnetic[3]
    magnetic susceptibility+20.6·10−6 cm3/mol[4]
    young's modulus13 gpa
    shear modulus4.9 gpa
    bulk modulus9.6 gpa
    mohs hardness1.25
    cas number7440-39-3
    history
    discoverycarl wilhelm scheele (1772)
    first isolationhumphry davy (1808)
    main isotopes of barium
    iso­tope abun­dance half-life (t1/2) decay mode pro­duct
    130ba 0.11% (0.5–2.7)×1021 y εε 130xe
    132ba 0.10% stable
    133ba syn 10.51 y ε 133cs
    134ba 2.42% stable
    135ba 6.59% stable
    136ba 7.85% stable
    137ba 11.23% stable
    138ba 71.70% stable
    category category: barium
    | references

    barium is a chemical element with the 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. its hydroxide, known in pre-modern times as baryta, does not occur as a mineral, but can be prepared by heating barium carbonate.

    the most common naturally occurring minerals of barium are barite (now called baryte[5][6]) (barium sulfate, baso4) and witherite (barium carbonate, baco3), both insoluble in water. the name barium originates from the alchemical derivative "baryta", from greek βαρύς (barys), meaning "heavy". baric is the adjectival form of barium. barium was identified as a new element in 1774, 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, as well as in a purer form, as x-ray radiocontrast agents for imaging the human gastrointestinal tract. the soluble barium ion and soluble compounds are poisonous, and have been used as rodenticides.

  • characteristics
  • history
  • occurrence and production
  • applications
  • toxicity
  • see also
  • references
  • external links

Barium, 56Ba
Barium unter Argon Schutzgas Atmosphäre.jpg
Barium
Pronunciationm/ (BAIR-ee-əm)
Appearancesilvery gray; with a pale yellow tint[1]
Standard atomic weight Ar, std(Ba)137.327(7)[2]
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
caesiumbariumlanthanum
Atomic number (Z)56
Groupgroup 2 (alkaline earth metals)
Periodperiod 6
Blocks-block
Element category  Alkaline earth metal
Electron configuration[Xe] 6s2
Electrons per shell2, 8, 18, 18, 8, 2
Physical properties
Phase at STPsolid
Melting point1000 K ​(727 °C, ​1341 °F)
Boiling point2118 K ​(1845 °C, ​3353 °F)
Density (near r.t.)3.51 g/cm3
when liquid (at m.p.)3.338 g/cm3
Heat of fusion7.12 kJ/mol
Heat of vaporization142 kJ/mol
Molar heat capacity28.07 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)
ElectronegativityPauling scale: 0.89
Ionization energies
  • 1st: 502.9 kJ/mol
  • 2nd: 965.2 kJ/mol
  • 3rd: 3600 kJ/mol
Atomic radiusempirical: 222 pm
Covalent radius215±11 pm
Van der Waals radius268 pm
Color lines in a spectral range
Spectral lines of barium
Other properties
Natural occurrenceprimordial
Crystal structurebody-centered cubic (bcc)
Body-centered cubic crystal structure for barium
Speed of sound thin rod1620 m/s (at 20 °C)
Thermal expansion20.6 µm/(m·K) (at 25 °C)
Thermal conductivity18.4 W/(m·K)
Electrical resistivity332 nΩ·m (at 20 °C)
Magnetic orderingparamagnetic[3]
Magnetic susceptibility+20.6·10−6 cm3/mol[4]
Young's modulus13 GPa
Shear modulus4.9 GPa
Bulk modulus9.6 GPa
Mohs hardness1.25
CAS Number7440-39-3
History
DiscoveryCarl Wilhelm Scheele (1772)
First isolationHumphry Davy (1808)
Main isotopes of barium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
130Ba 0.11% (0.5–2.7)×1021 y εε 130Xe
132Ba 0.10% stable
133Ba syn 10.51 y ε 133Cs
134Ba 2.42% stable
135Ba 6.59% stable
136Ba 7.85% stable
137Ba 11.23% stable
138Ba 71.70% stable
Category Category: Barium
| references

Barium is a chemical element with the 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. Its hydroxide, known in pre-modern times as baryta, does not occur as a mineral, but can be prepared by heating barium carbonate.

The most common naturally occurring minerals of barium are barite (now called baryte[5][6]) (barium sulfate, BaSO4) and witherite (barium carbonate, BaCO3), both insoluble in water. The name barium originates from the alchemical derivative "baryta", from Greek βαρύς (barys), meaning "heavy". Baric is the adjectival form of barium. Barium was identified as a new element in 1774, 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, as well as in a purer form, as X-ray radiocontrast agents for imaging the human gastrointestinal tract. The soluble barium ion and soluble compounds are poisonous, and have been used as rodenticides.