**Key information about energy level/shell**

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 2^{nd} shell or energy

level

n= 3 means 3^{rd} shell or energy

level

n= 4 means 4^{th} shell or energy

level

n= 5 means 5^{th} shell or energy

level

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 8^{th} shell.

How?

Do you remember

2n^{2} rule?

If we have 8

shells we can accommodate 128 elements.

2×8^{2}=

128

2.

Azimuthal quantum

number:

This

tells about subshells in a shell or energy level.

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.