Question

What is the electron configuration for a nitrogen $3^-$ ?

Answer 1

To solve the given question, the concepts to be cleared are about Quantum number, shells, sub-shells, orbitals, Pauli Exclusion Principle, Aufbau Rule, and P fund's Rule.
Quantum number is basically the address of an electron in an atom. Shells are the permitted orbits where an electron revolves with fixed angular momentum. Subshell is a division under the shell that contains orbital or orbitals.

Complete step by step answer:
The formula for nitride ion is $N^{3-}$ . Here, the total number of electrons in the ion is $10$ .
The four quantum numbers are Principal Quantum Number which denotes the shell, Azimuthal Quantum Number denoting sub-shell, Magnetic Quantum Number, and Spin Magnetic Number.
The sub-shells are s,p,d,f, . . . . . . and so on. They are filled on the basis of energy with $n+l$ rule.

So, $N^{3-}$ can be represented as $1s^2 2s^2 2p^6$ .

Additional Information:
1. Pauli’s Exclusion Principle states that any $2$ electron can never have all the same $4$ quantum numbers.
2. The rule explains the filling of electrons according to energy level.
3. P fund’s Rule explains that every orbital with one electron then fills another electron.
4. The magnetic quantum number differentiates orbitals in a given subshell. The l is always less than shell when l=0,s;l=1,p;l=2,d;l=3,f; and so on. 5\. 2 $Electrons are present in s,$ 6 $in p,$ 10 $in d and$ 14 $ in f.

Note:
During the electronic configuration, always make sure to write with inner to outer shells but fill the electron according to energy. The energy of $3d$ is more than $4s$ but $3d$ is written inner to $4s$ .