Quantum model of atom and quantum numbers

Key information about energy level/shell

 Quantum mechanical model: This model is based on Uncertainty principle

and Schrodinger’s equation. This model provides four types of numbers called quantum numbers.

 

1.    
Principal quantum number:

It tells about energy level or shell. It is denoted by “n”.

n= 1 means first shell or energy level

n= 2 means 2nd shell or energy
level

n= 3 means 3rd shell or energy
level

n= 4 means 4th shell or energy
level

n= 5 means 5th shell or energy
level

Some times
students ask about maximum number of shell can be in a atom. Is it related to
periodic table?

Actually each
element discovered so far is given an atomic number and all the elements fit up
to 8th shell.

How?

Do you remember
2n2 rule?

If we have 8
shells we can accommodate 128 elements.

 

2×82=
128

 

2.    
Azimuthal quantum
number:

This
tells about subshells in a shell or energy level. It is denoted by “l”.

It
has values from 0 to n-1.

For
example: n=1 has l=0 why?

n-1
is 1-1=0

n=5
has l=0,1,2,3,4 why up to 4?

All
values from 0 to n-1.

 

Each
value of l is related to one subshell.

l=0
means subshell s

l=1
means subshell p

l=2
means subshell d

l=3
means subshell f

3.    
Magnetic quantum
number (magnetic spin)

It tells about
orbitals in a subshell.

It is denoted
by m.

It has values from –l to +l through 0 on number line.

It means l=0
means s subshell which has m=0

Each value of m
means one orbital.

 

Hence n=2 has l=0,1
means s and p subshell means m=-1,0,+1 so total 3 orbitals in p subshell.

 

4.    
Spin quantum number:

It
tells about spin of electron. Out of two electron of one orbital, spin clock
wise another anti clock wise.

­

 

 

This article was written by Anup Sharma

I am a life- long learner and learned not only to be an effective IB teacher but an Educational leader. I have motivated and guided thousands of students and tens of teachers till now. I have worked as educational leader in schools and successfully motivated the team to perform at their best. As an Educational leader I organised many events and competitions of both academics and sports. I have conducted Public examinations of a state of Diu as Centre superintendent appointed directly by Govt of India. More About Me

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