Assertion (A): While going from left to right | vedclass

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(A) In the periodic table,as we move from left to right,the atomic size decreases due to an increase in effective nuclear charge.For the $4f$-series (

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Both $(A)$ and $(R)$ are correct and $(R)$ is the correct explanation of $(A)$

Vedclass · Answer

(A) In the periodic table,as we move from left to right,the atomic size decreases due to an increase in effective nuclear charge.For the $4f$-series (lanthanoids),the decrease in atomic size is less pronounced due to the poor shielding effect of $4f$-electrons,which leads to lanthanoid contraction.Conversely,the $3d$-series elements show a more rapid decrease in atomic size compared to the $4f$-series because $3d$-electrons provide better shielding than $4f$-electrons,but the overall effective nuclear charge increase is more dominant in the $3d$ transition series.Therefore,both Assertion $(A)$ and Reason $(R)$ are correct,and $(R)$ is the correct explanation of $(A)$.

Assertion $(A)$: While going from left to right in the periodic table,the atomic size decreases more rapidly for the $3d$-series compared to the $4f$-series of elements.
Reason $(R)$: $3d$-electrons experience lesser shielding than $4f$-electrons.

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Assertion $(A)$: While going from left to right in the periodic table,the atomic size decreases more rapidly for the $3d$-series compared to the $4f$-series of elements.Reason $(R)$: $3d$-electrons experience lesser shielding than $4f$-electrons.