56 2 · 8 · 18 · 18 · 8 · 2

Barium, Ba, element 56

Alkaline earth metal· Period 6· Group 2· s-block

Configuration [Xe]6s2

Atomic weight
137.327Da
Phase
solid
Density
3.62g/cm³
Melting point
1,000.15K 727 °C
Boiling point
2,118.15K 1,845 °C
Electronegativity
0.89

Silvery-white reactive element, belonging to group 2 of the periodic table. Soluble barium compounds are extremely poisonous. Identified in 1774 by Karl Scheele and extracted in 1808 by Humphry Davy. Description from mendeleev.

Back to the table
The outermost shell: the valence electronsThe inner shellsThe nucleus One bead for each electron, on the ring of its shell, counted from the nucleus out. The rings turn at their own pace; the model is Bohr's picture of the atom, which places electrons in shells but not on true orbits.

Atomic properties

5 of 5 fields have a value for barium

Atomic weight The standard atomic weight. For an element with no stable isotope, the mass of its longest-lived isotope.
137.327Da
Source: mendeleev
Electron configuration
[Xe]6s2
Source: mendeleev
Uncertainty of the atomic weight
0.007Da
Source: mendeleev
Electron configuration in full The electron configuration with the noble-gas core written out.
1s22s22p63s23p63d104s24p64d105s25p66s2
Source: Worked outfrom electron configuration
Electrons in each shell Counted from the electron configuration, from the first shell outward.
2 · 8 · 18 · 18 · 8 · 2
Source: Worked outfrom electron configuration

Screening of each subshell

Clementi's screening constants: how much of the nucleus's charge the other electrons hide from an electron in each subshell. What is left is the effective nuclear charge it feels.

SubshellScreening σEffective charge Z − σ
1s1.113954.8861
2s14.753241.2468
2p4.190451.8096
3s18.844437.1556
3p18.683637.3164
3d13.975742.0243
4s28.0827.92
4p29.196826.8032
4d32.21623.784
5s39.380516.6195
5p41.199514.8005
6s48.4257.575