Cesium Lanthanum

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

Symbol

Atomic number

Group

Period

Block

Element category

Alkaline Earth Metal

Physical properties

Phase at STP

Solid

Density

3.51 g/cm³

Atomic weight

137.328 u

Melting point

1000 K
726.85 °C
1340.33 °F

Boiling point

2118 K
1844.85 °C
3352.73 °F

Atomic properties

Electronegativity (Pauling Scale)

0.89

Electron affinity

13.954 kJ/mol

Oxidation states

+1, +2
(a strongly basic oxide)

Ionization energies

1	502.9 kJ/mol
2	965.2 kJ/mol
3	3600 kJ/mol

Electron configuration

Elektronkonfiguration (shorthand)

[Xe] 6s²

Electron configuration

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 6s²

Electrons per shell

2, 8, 18, 18, 8, 2

History

Discovered

1772

Discovered by

Carl Wilhelm Scheele