SymbolBa
Latin nameBaryum
Atomic number56
Period6
Element categoryAlkaline earth metals
Relative atomic mass137.327
GroupII.A
Electronegativity
0.9
Oxidation numbers
2
Electron configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 6s2
Density [g/cm3]
3.5
State
Solid
Melting point [°C]
725
Boiling point [°C]
1640
Thermal conductivity [W m-1K-1]
18.4
Heat capacity [J K-1g-1]
0.204
Discovery
1808
Hardness [Mohs scale]
1.25
Young's modulus [GPa]
13
Electrical conductivity [S m-1]
2.8 · 106
Shear modulus [GPa]
4.9
1.st ionization energy [eV]
5.2117
2.nd ionization energy [eV]
10.004
Stable isotopes
7
Unstable isotopes
17