Question

Considering $H_{2}O$ as weak field ligand, the number of unpaired electrons in ${\left[Mn{\left(H_{2}O\right)}_6\right]}^{2+}$ will be:

[Atomic number of $Mn=25$]

• A. 5
• B. 2
• C. 4
• D. 3

Answer 1

The correct option is A 5

Electronic configuration of Mn is $\left[Ar\right]4s^{2}3d^5$

In the complex, $[Mn{\left(H_{2}O\right)}_6{]}^{2+}$, charge on $H_{2}O$ will be zero.

So electronic configuration of $M{n}^{+2}$ will be $\left[Ar\right]4s^{0}3d^5$.

The 5 electrons in the d-shell will occupy 5-d orbitals making them all unpaired as shown.

No. of unpaired electrons in the above complex in the metal ion is 5.