Question

Define quantum number?

Answer 1

Hii...

Quantum numbers are the number which gives a complete description about an electron in an atom .

There are 4 quantum numbers i.e.

1. Principal Quantum Number ( n ) => It defines the main shell to which an electron belongs.

2. Azimuthal Quantum Number => It tells us about no. of subshell present in main shell.

3. Magnetic Quantum Number => It gives information about the level of degeneracy of the orbitals.

4. Magnetic Quantum Number => It tells us whether the electron in an orbital is spinning upward or downward direction i.e. +1/2 and -1/2 .

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Hope this helps !! ☺️

Answer 2

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$\textbf{QUANTUM NUMBER}$

The set of numbers which gave complete information about the electron in an atom is known as Quantum Number

Ex :- It's shape, energy, orientation, spin etc.

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$\textbf{TYPES OF QUANTUM NUMBER}$


$\textbf{1) Principle Quantum Number}$

→ It is denoted by n (shells).

→ It is the shell number of an atom. It can be n = 1,2,3,..... It determines the size and energy of orbital. Number pf electrons in a particular shell can be calculated by 2n².

→ Ex :-
n = 1 (K), 2 (L), 3 (M), 4 (N).
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$\textbf{2) Azimuthal Quantum Number}$

→ It is denoted by l (subshell).

→ It shows the number of subshell or sublevels. It defines the 3- dimensional shape of an orbital. It's value range from 0 to (n-1).

→ Ex :-
If n = 1 then, l = 0
n = 2, then l = 0, 1
n = 3, then l = 0, 1, 2

* It is also known as Subsidiary or Angular Quantum Number.
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$\textbf{3) Magnetic Quantum Number}$

→ It is denoted by m (orbitals).

→ It gives the magnetic orientation of electrons. It can have value from - l to + l.

→ Ex :-
If n = 1, l = 0 then m = 0
n = 2, l = 0, 1 then m = -1, 0 , +1
n = 3, l = 0, 1, 2 then m = -2, -1, 0, +1, +2
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$\textbf{4) Spin Quantum Number}$

→ It is denoted by s (spins of electrons).

→ Gives orientation or spin of electron. It can be clockwise and anti clockwise. For every value of m, Spin Quantum Number has two values. + ½, - ½.

→ Ex :- + ½ for clockwise spin and - ½ for anticlockwise spin.

* One orbital can have two electrons. Due to opposite spin, the magnetic field produced are opposite which can cause attraction between electrons in an orbitals.

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# DEGENERATE ORBITALS :-

Orbitals belonging to same subshells are having same energy and termed as Degenerate Orbitals.

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