Question

Which of the following lanthanoid ions is diamagnetic?
(At. nos. $Ce=58,Sm=62,Eu=63,Yb=70$)

• A. $E{u}^{2+}$
• B. $Y{b}^{2+}$
• C. $C{e}^{2+}$
• D. $S{m}^{2+}$

Answer 1

The correct option is B $Y{b}^{2+}$

The corresponding electronic configurations are
$S{m}^{2+}(Z=62):\left[Xe\right]4f^6$
$E{u}^{2+}(Z=63):\left[Xe\right]4f^7$
$Y{b}^{2+}(Z=70):\left[Xe\right]4f^{14}$
$C{e}^{2+}(Z=58):\left[Xe\right]4f^{1}5d^1$
Thus only $Y{b}^{2+}$ is diamagnetic.