Question

Which of the following is not a consequence of lanthanide contraction?

• A. From $L{a}^{+3}\text{to}L{u}^{+3}$, the ionic radii changes from 106 pm to 85 pm.
• B. As the size of the lanthanide ions decreases the basic strength increases.
• C. The atomic radii of 4d and 5d series is similar.
• D. None of the above

Answer 1

The correct option is B As the size of the lanthanide ions decreases the basic strength increases.

The small average decreases in the atomic size is responsible for a small decrease in electronegativity and standard oxidation potential of lanthanides. As the size of the lanthanide ions decreases the covalent character of $M—OH$ bond increases and hence basic strength decreases.