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SUBJECT-CHEMISTRY

CHAPTER-ATOMIC STRUCTURE

SUBTOPIC- QUANTUM NUMBERS

KEY NOTES :

 When Schrödinger equation is solved for hydrogen atom, the solution
gives the possible energy levels the electron can occupy and the
corresponding wave function(s) (ψ) of the electron associated with each

energy level. These quantized energy states and corresponding wave
functions which are characterized by a set of three quantum numbers.
 The integers or constants which gives the total information about an
electron are called quantum numbers.
 TYPES OF QUANTUM NUMBERS :
 Principal quantum number (n)

 Azimuthal quantum number(l)
 Magnetic quantum number(m)
 Spin quantum number (s)
 Principal quantum number (n)
 It gives the idea of the shell where the electron is revolving.
i.e. if n=1 it represents K – Shell

n=2 it represents L-Shell
n=3 it represents M-Shell and so on.
 The energy of a particular shell is given by ,
 1312
E   z 2 KJ / mole
n
n 2
 The radius of an orbit is given by,
. 0 529
0
r   n 2 A
n
z
 Angular momentum of electron in an orbit is given by,
nh
mvr 
2 
 Maximum number of electrons that can accommodate in a shell
2
is given by 2n rule. So,
K-Shell – 2 electrons
L-Shell – 8 electrons
M-Shell – 18 3l3ctrons
 Significance- By using this quantum number we can calculate the
energy and radius of a shell.