Question

The correct order of atomic radii is (given that atomic numbers of Yb = 70, Pm = 61 Ce = 58,La=57) a) Yb ​

Answer 1

Given:

(given that atomic numbers of Yb = 70, Pm = 61 Ce = 58,La=57)

Correct order of atomic radii=?

Ionic radii decrease as we move across the lanthanide series due to lanthanide contraction.

As all ions are in +3 oxidation state, ionic radii will follow the trend of atomic radii:

$\mathrm{Y} \mathrm{b}^{3+}<\mathrm{Pm}^{3+}<\mathrm{Ce}^{3+}<\mathrm{La}^{3+}$

Hence the order of atomic radii is  $\mathrm{Y} \mathrm{b}^{3+}<\mathrm{Pm}^{3+}<\mathrm{Ce}^{3+}<\mathrm{La}^{3+}$