Principal quantum number, azimuthal quantum number, magnetic quantum number
The atom has K shell, L shell, M shell and other shells.
We learned it in Part 1
The electron shells have s orbital, p orbital, d orbital and other orbitals.
We also learned it in Part 4
What do decide it?
The answers are principal quantum number, azimuthal quantum number and magnetic quantum number.
K shell is closest to the nucleus.
So its number is 1.
L shell is second closest to the nucleus.
So its number is 2.
We express it using a character "n".
K shell is expressed as n= 1.
In the same way L shell is expressed as n= 2.
We made to correspond to the natural number in order from closest to the nucleus.
In short, principal quantum number "n" distinguish between electrons which are present in the electron shell.
Azimuthal quantum number determine the shape of the orbit.
It takes an integer value 0, 1, ... n-2, n-1.
We express it using a character "l".