Question

give scientific reason, why 4s orbital is filled before 3d orbital​

Answer 1

Answer:

4s orbital is filled first . because According to auffbau's rule orbitals filled According to their increasing energies. 4s orbital has lesser energy than 3d orbital.

another reason is according to n+l rule

according to n+l rule the orbital is filled first whose n+l value is less.

4s=4+0 =4

3d=3+2=5

4s has lesser n+l value so they filled first