Question

The lanthanoid ion which contains unpaired electrons is:

• A. $C{e}^{4+}$
• B. $Y{b}^{2+}$
• C. $L{u}^{3+}$
• D. $E{u}^{2+}$

Answer 1

Answer: (D)

$E{u}^{2+}$

• The species are either diamagnetic, meaning they have no unpaired electrons, or paramagnetic, meaning that they do have some unpaired electrons. The diamagnetic ions are: $L{a}^{3+}$, $L{u}^{3+}$, $Y{b}^{2+}$and $C{e}^{4+}$.
  
• Hence $E{u}^{2+}$ is the only ion which is paramagnetic.