5s subshell represent that n is equal to 5 and l is equal to 0.
2p subshell represent that n is equal to 2 and l is equal to 1.
3d subshell represent that n is equal to 3 and l is equal to 2.
The numbers gives us the value of n and the letter gives us the value of l.
s means l = 0
p means l = 1
d means l = 2
f means l = 3
