Question

The magnitude of screening effect depends upon the number of:
A.Inner electrons
B.Outer electrons
C.Bonds order
D.Both (A) and (B)

Answer 1

Hint: The decrease in the nuclear force of attraction on the valence electrons or outermost electrons due to the repulsive forces of inner lying electrons is called screening effect.As a result of the screening effect, the outermost electrons do not experience the complete nuclear charge.

Complete step by step answer:
The energy of an electron depends upon the nuclear charge, principal quantum number and the presence of electrons in lower energy levels.
In a multielectron atom, the inner electrons act as a screen between the nucleus and electron present in the valence shell of the atom. These screening electrons reduce the effect of the attraction of the nucleus for the electrons in the outermost orbital. This effect is called the screening effect or the shielding effect.
The effective nuclear charge is the nuclear attractive force experienced by the electrons when it is shielded by the inner lying electrons. In other words, it is the nuclear charge reduced by the shielding or screening from any intervening electrons.
For a hydrogen atom, there is a single electron and so the screening effect is absent. Thus, the attractive pull exerted by the nucleus is not affected.
But for a multielectron atom like lithium, there is more than one electron. The inner 1s orbital electrons of lithium will repel the outermost shell electron.
Therefore, the magnitude of the screening effect depends on the number of inner electrons and

So the correct option is A.

Note:
The effective nuclear charge for an electron in the configuration of an atom can be calculated by means of the following correlation.
${{\text{Z}}_{{\text{eff}}}}{\text{ = }}{{\text{Z}}_{{\text{actual}}}}{\text{ - S}}$
Here, S is the screening constant, ${{\text{Z}}_{{\text{eff}}}}$ is the effective nuclear charge and ${{\text{Z}}_{{\text{actual}}}}$ is the actual nuclear charge for the electron.
The magnitude of the screening constant S determines the extent to which an electron is shielded or screened by other electrons in an atom from the nuclear charge. The magnitude of the screening constant S is evaluated by using the Slater rules.