Question

Which of the following ions has the highest magnetic moment?

• A. $F{e}^{2+}$
• B. $M{n}^{2+}$
• C. $C{r}^{3+}$
• D. $V^{3+}$

Answer 1

The correct option is B $M{n}^{2+}$

$F{e}^{2+}-\left[Ar\right]3d^6$

$\uparrow \downarrow$

$\uparrow$

$\uparrow$

$\uparrow$

$\uparrow$

$M{n}^{2+}-\left[Ar\right]3d^5$

$\uparrow$

$\uparrow$

$\uparrow$

$\uparrow$

$\uparrow$

$C{r}^{3+}-\left[Ar\right]3d^4$

$\uparrow$

$\uparrow$

$\uparrow$

$\uparrow$

$V^{3+}-\left[Ar\right]3d^2$

$\uparrow$

$\uparrow$

Clearly, $M{n}^{2+}$ has maximum number of unpaired electrons.
As, ${\mu }_s=\sqrt{n(n+2)}B.M.$
So, magnetic moment is directly proportional to number of unpaired electrons.
As, $M{n}^{2+}$ has maximum number of unpaired electrons, therefore, it has highest magnetic moment.