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56Ba137.328
Barium
Alkaline Earth MetalBarium 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.
Phase: Solid
2, 8, 18, 18, 8, 2
Physical Properties
Atomic Mass137.3277 u
Density3.51 g/cm³
Melting Point1000 K
Boiling Point2118 K
Molar Heat28.07 J/(mol·K)
Period6
PhaseSolid
Chemical Properties
Electron Configuration1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2
Semantic Config[Xe] 6s2
Shells2, 8, 18, 18, 8, 2
Electron Affinity13.954 kJ/mol
Electronegativity0.89
Ionization Energies
IE1: 502.9 kJ/molIE2: 965.2 kJ/molIE3: 3600 kJ/mol
Discovery
Discovered byCarl Wilhelm Scheele