NEETChemistryClassification of Elements and Periodicity in Properties
Which of the following statements regarding the ionisation enthalpies of transition elements is incorrect?
Options
- AThe successive addition of electrons to the inner (n-1)d orbitals decreases the shielding of outer ns electron
- BThe first ionisation enthalpy generally increases along a transition series due to the corresponding increase
- CThe shielding of outer ns electrons by the inner (n-1)d electrons partially offsets the effect of increasing n
- DThe variation in first ionisation enthalpy across a transition series is much smaller than that observed acros
Correct answer
A. The successive addition of electrons to the inner (n-1)d orbitals decreases the shielding of outer ns electron
Step-by-step solution
The incorrect statement is the first one. As we move from left to right across a transition series, electrons are successively added to the inner (n-1)d orbitals. These inner d electrons shield the outer ns electrons from the increasing nuclear charge. Although the shielding provided by d electrons is relatively poor compared to s or p electrons, the total shielding effect increases (not decreases) as more electrons are added. This shielding partially offsets the increased nuclear charge. Because of this opposing e