Transition and InnerTransition Elements - Result Question 113
####12. The effect of lanthanoid contraction in the lanthanoid series of elements by and large means
(2019 Main, 10 Jan I)
(a) increase in atomic radii and decrease in ionic radii
(b) decrease in both atomic and ionic radii
(c) increase in both atomic and ionic radii
(d) decrease in atomic radii and increase in ionic radii
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Solution:
- Lanthanoid contraction in the lanthanoid series takes place due to the presence of electron(s) in the $4 f$-orbitals. $f$-orbitals have poor shielding effect. As a result, the effective nucleur charge will be more experienced by the $5 d$ and $6 s$ - electrons and it will cause contraction or decrease in both atomic and ionic radii.
