Question

The order of the screening effect of electrons of s, p, d and f orbitals of a given shell of an atom on its outer shell electrons is:
A.s > p > d > f
B.f > d > p > s
C.p > f > d > s
D.f > p > s > d

Answer 1

Hint: The Shielding effect or screening effect is the reduction in the effective nuclear charge on the electron cloud, due to differences in the attraction forces between electrons and the nucleus.

Complete answer:
- The shielding effect can be defined as a reduction in the effective nuclear charge on the electron cloud, which is due to a difference in the attraction forces on the electrons in the atom.
- The s orbital has the greatest effect to reduce the force of attraction between the outermost electron and nucleus due to its effective charge density followed by p > d > f.
- According to orbital order, S orbital is closest to the nucleus followed by the P orbital, D orbital and finally the F orbital.
- So, as per the screening effect, S orbital being close to the nucleus lacks screening from any other orbital as it is the first and the closest orbital.
- P orbital electrons are loosely bound with greater size than s block elements as they undergo screening from S orbital electrons.
- Similarly, D orbital electrons undergo screening from S and P block orbitals and finally, F orbital also undergoes screening from all the other orbitals.
- Hence, the F block elements are generally big in size with less nuclear charge acting on their outermost electrons.

Therefore, the answer to the question is (A) s > p > d > f.

Note:
For the same shell, screening effect is considerably decreased in the order. Thus, for n=4, 4s orbital has maximum screening effect and 4f orbital has the lowest screening effect.