Question

The d electrons have a screening effect
A. much less than s-electrons.
B. much more than s-electrons.
C. equal to s-electrons.
D. equal to p-electrons.

Answer 1

Hint: The screening effect is the power of the electrons to shield to the outer most electrons from the attraction of the nucleus. The screening power of the electrons depends upon the orbitals in which the electrons are present.

Complete step by step answer:
The electrons are present in orbitals at different energy levels. As the energy level increases, the attraction of the nucleus and electrons of that energy level decreases. The reason is the screening effect.

The nucleus has a minimum attraction on the outermost shell electrons because the electrons present in the inner shell repel the outermost shell electrons and stop the nuclear charge to reach the outer shell. So, the distance between outer- most shell electrons and the nucleus increases and the outermost shell electrons feel the less effective nuclear charge.

The screening effect depends upon the shape of the orbital. The shape of the s-orbital is spherical, the shape of the p-orbital is a dumbbell and the shape of the d-orbital is a double dumbbell.

Due to spherical shape s-orbital has a maximum density of electrons whereas the p-orbital has somewhat diffuse electron density and d-orbital has more diffuse electron density.

So, the electrons in the s-orbital have a high screening effect then p and d-orbital and electrons in the p-orbital have a higher screening effect than d-orbital.

So, the decreasing order of the screening effect of the orbital is as follows:
S-orbital > p-orbital> d-orbital

Thus, the correct option is A.


Note:
The screening effect is also known as the shielding effect. As the screening effect or shielding effect increases the effective nuclear charge decreases. As the number of the inner shell increases the shielding effect increases.