Question

What do you mean by electronic configuration?

Answer 1

Hint: The distribution of electrons into different orbitals of an atom is called the electronic configuration. In every neutral atom, the number of electrons present in the atom is equal to the number of protons and they are equal to the atomic number of that atom. Not only electrons and protons, an atom also has neutrons in it. They may or may not be equal to the number of protons present in the atom.

Complete answer:
To write the electronic configuration, there are three important sets of rules. They are:
1) Aufbau principle
2) Pauli’s exclusion principle
3) Hund’s rule
The Aufbau principle states that, in the ground state of an atom, the electrons occupy atomic orbitals in their increasing order of increasing energies given by the $n + l$ rule. Energy is higher if the value of $n + l$ is higher. If two orbitals have the same value of $n + l$ , then the orbital having lower principal quantum number will have the lower energy and so that orbital will be occupied first. Pauli's exclusion principle states that no two electrons in the same atom can have identical values of all four quantum numbers. This means only two electrons can occupy the same orbital and the two electrons present in the same orbital must have opposite spins.

Note:
According to the Hund’s rule in chemistry, every orbital in a subshell is singly occupied with one electron before any other orbital is doubly occupied. And all the electrons in the singly occupied orbitals have the same spin.