NEETChemistryd and f Block Elements
It is a well-known fact that the 5f electrons shield the nuclear charge less effectively than the 4f electrons. Which of the following is a direct observable consequence of this poor shielding?
Options
- ALanthanoids show a greater element-to-element decrease in atomic size than actinoids.
- BThe decrease in atomic size from element to element is greater in the actinoid series compared to the lanthano
- CActinoids exhibit a smaller range of oxidation states than lanthanoids.
- DThe 5f orbitals are more deeply buried in the atom than the 4f orbitals.
Correct answer
B. The decrease in atomic size from element to element is greater in the actinoid series compared to the lanthano
Step-by-step solution
The shielding effect of 5f electrons is poorer than that of 4f electrons. As a result, the effective nuclear charge experienced by the valence electrons increases more sharply from element to element in the actinoid series. This causes a more pronounced actinoid contraction, meaning the decrease in atomic and ionic size from one element to the next is greater in actinoids than in lanthanoids. Actinoids actually show a larger number of oxidation states because of the comparable energies of 5f , 6d and 7s levels. Als