Question

First IE of 5d series elements are higher than those of 3d and 4d series elements. This is due to :

• A. Bigger size of atoms of 5d-series elements than 3d-series elements.
• B. Greater effective nuclear charge is experienced by valence electrons because of the
• C. (1) and (2) both.
• D. None of these.

Answer 1

Answer: (B)

Greater effective nuclear charge is experienced by valence electrons because of the

Answer 2

The order of shielding effect of various orbital electrons is s > p > d > f. Due to the poor shielding effect of 4f- electrons in 5d-series elements, there is enhanced increase in effective nuclear charge. As a result of this the valence electrons are tightly bound with the nucleus and thus their removal require higher energy.