NEETChemistryd and f Block Elements
The absorption bands in the electronic spectra of actinoid ions are relatively broader and more complex compared to the narrow bands of lanthanoid ions. What is the primary reason for this difference?
Options
- AThe 5f orbitals are less deeply buried than the 4f orbitals, allowing stronger interaction with surrounding li
- BThe 5f orbitals are more deeply buried than the 4f orbitals, resulting in complete shielding from the ligand f
- CThe absorption in actinoid ions is primarily due to d-d transitions rather than f-f transitions.
- DActinoids possess significantly higher first ionization enthalpies than lanthanoids.
Correct answer
A. The 5f orbitals are less deeply buried than the 4f orbitals, allowing stronger interaction with surrounding li
Step-by-step solution
In lanthanoids, the 4f orbitals are deeply buried and well-shielded by the outer 5s and 5p electrons, leading to narrow, line-like absorption bands because the ligand field has very little effect on them. In contrast, the 5f orbitals in actinoids are less deeply buried and extend further outward than the 4f orbitals. As a result, they are less effectively shielded and interact more strongly with the surrounding ligand environment. This stronger ligand field interaction leads to broader and more complex absorption b