Concept:Electron affinity is the energy released when an electron is added. A stronger pull from the nucleus results in a higher electron affinity.
Formula:$$ \text{Electron Affinity} \propto \frac{1}{\text{Atomic Radius}} $$
Solution:- As you move down a group, new electron shells are added, causing the atomic radius to increase significantly.
- The incoming electron must enter a shell that is much farther away from the positive nucleus.
- Additionally, the increased number of inner shells creates a strong shielding effect.
- Both factors weaken the nucleus's attractive force on the incoming electron, resulting in less energy being released (decreased electron affinity).
Why other options are incorrect:- Option A: While proton number increases, its effect is completely overwhelmed by the increase in radius and shielding.
- Option B & Option D: These are factually incorrect statements; shielding and atomic radius both increase down a group.
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