Question

How can I find the ground state?

Answer 1

Hint The answer here is based on the basic concept of chemistry which tells about the electronic configuration of an element where the electrons in it are to be filled according to Aufbau principle and then writing in terms of shorthand notation.

Complete step – by – step answer:
In the classes of inorganic chemistry, we have dealt with the basic concepts of chemistry that includes the filling of electrons in an atomic orbital and also several rules to be considered while filling such as Aufbau principle, Pauli’s exclusion principle and others.
We shall see the Aufbau principle and its rule for filling the orbitals in order to solve the above question.
- Aufbau principle states that in the ground state of an atom or an ion, the electrons are filled with the atomic orbitals that have the lowest available energy level before occupying the higher energy levels.
- based on this above rule, let us take an instance of an element and try to find the ground state electronic configuration of that atom.
- Consider a simple example of nitrogen with atomic number 7 where total electrons present in it are 7.
Now filling of the electrons according to the Aufbau principle is as follows:
Firstly, 1s orbital is filled as it has the lowest energy and according to Pauli's exclusion principle only a maximum of two electrons can be filled in each orbital with opposite spins, we can fill this 1s orbital by 2 electrons.
Now remaining electrons are $7-2=5$ . Thus, the next higher energy orbital is 2s and thus other two electrons are filled in this. The remaining electrons are $5-2=3$ .
Now, the next higher energy orbital is the 2p orbital which can hold 6 electrons maximum where two electrons in each p orbital are filled.
Thus, the remaining 3 electrons are in 2p orbital.

Therefore, the ground state electronic configuration of nitrogen can be written as, $1{{s}^{2}}2{{s}^{2}}2{{p}^{3}}$

Note: Note that the shorthand notation or the electronic configuration can also be written with the valence electrons outside the brackets preceded by the noble gas configuration and for nitrogen it is $[He] 2{{s}^{2}}2{{p}^{3}}$ and even this is called ground state configuration