Lesson eLearning

Which of the following lanthanide ions has the smallest ionic radius?

easy MCQ 1 mark Class 12 · Chemistry · d- and f-Block Elements
  1. Ce³⁺
  2. Eu³⁺
  3. Gd³⁺
  4. Lu³⁺
Answer
Lu³⁺

The correct answer is Lu³⁺ — Therefore, Lu³⁺ possesses the smallest radius among the listed ions.

Step-by-step solution

  1. Recall the concept of lanthanide contraction: ionic radii decrease steadily across the lanthanide series.
  2. Compare the given ions: Ce (atomic number 58) to Lu (atomic number 71). Lu is at the end of the series, hence experiences the greatest contraction.
  3. Therefore, Lu³⁺ possesses the smallest radius among the listed ions.
Common mistake: Choosing Ce³⁺ because it is the first lanthanide, forgetting the contraction trend.

Concept tested: Lanthanide contraction and ionic radii

Published · How this solution was prepared and checked

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