Question

why there is a need of sharing of electrons in electronic configuration

Answer 1

There is a need of sharing of electrons to attain a stable electronic configuration.
Elements form molecules by covalent or ionic bond.
In covalent bond there is sharing of electron and In ionic there is donate or accepting a pair of electron.

Hope you get your answer.

Answer 2

protons are present inside the nucleus and outside the nucleus they can not survive they vanished, so electrons are the only cause of making bonds electron do participate in chemical reaction (by the sharing of electrons from the outermost shell of an atom the element gain it's stability)