In a transition series, with an increase in atomic number the atomic radius does not change very much. Why is it so?
Answer: The added d-electrons shield the added nuclear charge almost equally — the two effects nearly cancel.
Solution
Across a transition series each step adds one proton and one (n−1)d electron.
The inner d-electron screens the outer ns electrons from the extra nuclear charge almost completely, so the effective nuclear charge — and hence the radius — changes very little through the middle of the series.
The inner d-electron screens the outer ns electrons from the extra nuclear charge almost completely, so the effective nuclear charge — and hence the radius — changes very little through the middle of the series.
CBSE Class 12 Board · 2002 · Delhi · Subjective