Question

Which of the following lanthanoid ions is diamagnetic?

• A. $Sm{}^{2+}$
• B. $Ce{}^{2+}$
• C. $Yb{}^{2+}$
• D. $Eu{}^{2+}$

Answer 1

The correct option is C

$Yb{}^{2+}$

$Yb{}^{2+}$ is diamagnetic as it lacks unpaired electrons.
Yb has outer electronic configuration of $4f{}^{14}$$5d{}^0$$6s{}^2$.
$Yb{}^{2+}$ has outer electronic configuration of $4f{}^{14}$$5d{}^0$$6s{}^0$.
Rest other have unpaired electrons so they are paramagnetic.
$S{m}^{2+}(Z=62)$
$\left[Xe\right]4f^{6}5d^{0}6s^0-6\text{unpaired}{e}^{-}$
$E{u}^{2+}(Z=63)$
$\left[Xe\right]4f^{7}5d^{0}6s^0-7\text{unpaired}{e}^{-}$
$C{e}^{2+}(Z=58)$
$\left[Xe\right]4f^{2}5d^{0}6s^0-2\text{unpaired}{e}^{-}$