Answer: The ion is [tex]Ca^{2+}[/tex]. The chemical symbol of the noble gas this ion is isoelectronic with Kr.
Explanation:
The given electronic configuration is,
[tex]M^{2+}:1s^22s^22p^63s^23p^6[/tex]
The number of electrons = 2 + 2 + 6 + 2 + 6 = 18 electrons
As the ion has a charge of +2 , that means it has lost two electrons so the the neutral element will have 2 more electrons i.e 18+2 = 20. The element has atomic number of 20 and the element will be Calcium with electronic configuration of
[tex]M: 1s^22s^22p^63s^23p^64s^2[/tex]
Thus the symbol of ion is [tex]Ca^{2+}[/tex]. the nearest noble gas with 18 electrons is Krypton with symbol Kr.
