Barium (Ba)

From Wikipedia, the free encyclopediaBarium is a chemical element with symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Because of its high chemical reactivity barium is never found in nature as a free element.

Barium in the periodic table

SymbolBa
Atomic number56
Group2
Period6
Blocks
Element categoryAlkaline Earth Metal

Physical properties

Phase at STPSolid
Density3.51 g/cm3
Atomic weight137.328 u
Melting point1000 K
726.85 °C
1340.33 °F
Boiling point2118 K
1844.85 °C
3352.73 °F

Atomära egenskaper

Electronegativity (Pauling Scale)0.89
Electron affinity13.954 kJ/mol
Ionization energies
1502.9 kJ/mol
2 965.2 kJ/mol
3 3600 kJ/mol

Electron configuration

Electron configuration1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 6s2
Electrons per shell2, 8, 18, 18, 8, 2

History

Discovered1772
Discovered byCarl Wilhelm Scheele