Ans :- Quantum numbersare important because they can be used to determine the electron configuration of an atom and the probable location of the atom's electrons.Quantum numbersare also used to determine other characteristics of atoms, such as ionization energy and the atomic radius.

Principal Quantum Number (n)—this designates thesizeof the orbital, also called theshell. The larger the value forn, the greater the average distance of an electron in the orbital from the nucleus and therefore the larger the orbital. (I could always remember this trend by relating it back to Coulomb’s Law of Attractive Forces.) From the equation that defines the line spectrum of Hydrogen, we can also know that the value fornrepresentsenergy levels.

Angular Momentum Quantum Number (l)—this describes theshapeof the orbital, but again, you can relate it back to the periodic table. The values oflare integers that depend on the value of the principal quantum number,n. For any given value ofn, the possible range of values forlgo from 0 ton- 1. Ifn= 1, there’s only one possible value ofl; that is, 0 (n - 1 where n = 1). Ifn= 2, there’s two values forl:0 and 1. Ifn= 3,lhas three values: 0, 1, and 2.

Magnetic Quantum Number (mlml)—this describes the orientation of the orbital in space, or the direction along the axes in which it faces. Within a subshell, the value of this depends on the value ofl. For a certain value ofl, there are (2l+ 1) integral values, or-l, … 0, … +l.

Electron Spin Quantum Number (msms)—where three quantum numbers are sufficient to describe an atomic orbital, an additional number becomes necessary to describe an electron that occupies the orbital. And for anygeneralorbital, two electrons occupy it.