Ac (Actinium) is an element with position number 89 in the periodic table.
Located in the VII period. Melting point: 1047 ℃. Density: 10.07 g/cm3.
The order of filling the orbitals with electrons in the Ac atom is an exception to the rule.
Expected electronic configuration
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f1
But in reality, one electron moves from the 5f orbital to the 6d orbital:
Electronic configuration of the Actinium atom in ascending order of orbital energies:
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 6d1
Electronic configuration of the Actinium atom in ascending order of the levels:
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 6d1 7s2
Reduced electronic configuration Ac:
[Rn] 6d1 7s2
Expected electronic configuration
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f1
But in reality, one electron moves from the 5f orbital to the 6d orbital:
Electronic configuration of the Actinium atom in ascending order of orbital energies:
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 6d1
Electronic configuration of the Actinium atom in ascending order of the levels:
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 6d1 7s2
Reduced electronic configuration Ac:
[Rn] 6d1 7s2
Below is the electronic diagram of the Actinium atom
Distribution of electrons over energy levels in the Ac atom
1-st level (K): 2
2-st level (L): 8
3-st level (M): 18
4-st level (N): 32
5-st level (O): 18
6-st level (P): 9
7-st level (Q): 2
1-st level (K): 2
2-st level (L): 8
3-st level (M): 18
4-st level (N): 32
5-st level (O): 18
6-st level (P): 9
7-st level (Q): 2
Oxidation states of Actinium: +3
Other elements
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Electronic configurations of other elements
Radium (Ra) electron configurationThorium (Th) electron configuration
Electronic configuration table
