Question

Which of the following cations has the strongest tendency towards complex formation?

• A. $ Sm^{3+} $
• B. $ Lu^{3+} $
• C. $ Gd^{3+} $
• D. $ Yb^{3+} $

Answer 1

Answer: (B)

The lanthanides do not have much tendency to form complexes due to low charge density because of their large size. However, the tendency to form complexes and their stability increases with increasing atomic number. Thus, among $Sm^{3+}, Lu^{3+}, Gd^{3+}, Yb^{3+}$ and $Lu^{3+}$ being the smallest in size with highest atomic number has the strongest tendency towards complex formation