Barium

Barium, ₀₀Ba

Barium
Pronunciation	/ˈbɛəriəm/ ​(BAIR-ee-əm)
Appearance	silvery gray; with a pale yellow tint[1]
Standard atomic weight Ar°(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 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
Phase at STP	solid
Melting point	1000 K ​(727 °C, ​1341 °F)
Boiling point	2118 K ​(1845 °C, ​3353 °F)
Density (near r.t.)	3.51 g/cm3
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)
Speed of sound thin 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[3]
Molar magnetic susceptibility	+20.6·10−6 cm3/mol[4]
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 v e
Main isotopes[5] 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 view talk edit | references

Barium is chemical element 56 on the periodic table. Its symbol is Ba. It contains 56 protons and 56 electrons. Its mass number is about 137.3. It is a metal.

1. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 112. ISBN 978-0-08-037941-8.
2. ↑ "Standard Atomic Weights: Barium". CIAAW. 1985.
3. ↑ 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.
4. ↑ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
5. ↑ 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.