Question

An atom has 2 electrons in the first (K)shell, 8 electrons in the second (L) shell and 2 electrons in the third (M) shell. Give its electronic configuration and find out the following:-
1.Atomic number
2.Total number of principal quantum numbers
3.Total number of sub-levels
4.Total number of s-orbitals
5.Total number of p-electrons

Answer 1

Dear student,

An atom has 2 electrons in the first (K)shell,
8 electrons in the second (L) shell
and 2 electrons in the third (M) shell
So, its electronic configuration : 1s² 2s² 2p⁶ 3s² or [ Ne] 3s²
1.Atomic number :12
2.Total number of principal quantum numbers Three (1,2,3)
3.Total number of sub-levels :Four (i.e.1s ,2s,2p, and 3s)
4.Total number of s-orbitals : Three (i.e.1s,2s, and 3s)
5.Total number of p-electrons :six (i.e.2p⁶)

Hence the atom is Magnesium (₁₂Mg) which is a s-block element.

Regards,