The electron configuration of Ca⁺² is most similar to that of Ar(Argon)
In an atom, there are levels of energy in the shell and sub-shell
This energy level is expressed in the form of electron configurations.
Writing electron configurations starts from the lowest to the highest sub-shell energy level. There are 4 sub-shells in the shell of an atom, namely s, p, d, and f. The maximum number of electrons for each sub-shell is
Charging electrons in the sub-shell uses the following sequence:
1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d¹⁰, 4p⁶, 5s², 4d¹⁰, 5p⁶, 6s², etc.
Calcium (symbol Ca) is an alkaline earth metal element with an atomic number of 20, so the number of electrons is 20 (for neutral atoms)
The electron configuration of Ca : [Ar] 4s² ⇒ 1s² 2s² 2p⁶ 3s²3p⁶4s²
For the Ca²⁺ cation, which has a +2 charge, it is obtained by removing 2 electrons, so that the electron configuration is the same as for the element Ar (argon): 1s² 2s² 2p⁶ 3s²3p⁶
