Chromium electron configuration

Cr (Chromium) is an element with position number 24 in the periodic table. Located in the IV period. Melting point: 1857 ℃. Density: 7.14 g/cm3.
The order of filling the orbitals with electrons in the Cr atom is an exception to the rule.
Expected electronic configuration
1s2 2s2 2p6 3s2 3p6 4s2 3d4
But in reality, one electron moves from the 4s orbital to the 3d orbital:

Electronic configuration of the Chromium atom in ascending order of orbital energies:
1s2 2s2 2p6 3s2 3p6 4s1 3d5

Electronic configuration of the Chromium atom in ascending order of the levels:
1s2 2s2 2p6 3s2 3p6 3d5 4s1

Reduced electronic configuration Cr:
[Ar] 3d5 4s1

Below is the electronic diagram of the Chromium atom
Orbital diagram of the Chromium atom
Distribution of electrons over energy levels in the Cr atom
1-st level (K): 2
2-st level (L): 8
3-st level (M): 13
4-st level (N): 1
Distribution of electrons in the Chromium

Valence electrons of Chromium

The number of valence electrons in a Chromium atom - 6.
Below are their quantum numbers (N - energy, L - angular momentum, M - magnetic moment, S - spin )
OrbitalNLMS
s400+1/2
d32-2+1/2
d32-1+1/2
d320+1/2
d321+1/2
d322+1/2
Oxidation states of Chromium: +1, +2, +3, +4, +5, +6
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