Illustrate rules for filling electrons in (n + l) orbital using an example.

Explanation

According to (n + 1) rule: a) In neutral atoms a subshell with lower value of (n + 1) has lower energy. Ex: 4s orbital hasloer energy than 3d orbital. For 4s orbital, n = 4 and 1 = 0. ·Hence, (n +1)= 4 + 0 = 4. For 3d orbital, n = 3 and 1= 2. Hence, (n +1)= 3 + 2 = 5.
b) If two subshells have equal value of(n + 1), the subshell with lower value of n has lower energy.
Ex:- consider 3 p and 4 s orbital. For 4 s orbital n = 4 and 1 = 0
Hence, (n + 1)= 4 + 0 = 4
For 3 p orbital n = 3 and l = 1
Hence (n + 1) = 3 1 = 4
Hence 3 p orbital has lower energy than 4 s because it has lower value of n.