Question

Pair of transition metal ions having the same number of unpaired electrons is :

• A. $\mathrm{V}^{2+}, \mathrm{Co}^{2+}$
• B. $\mathrm{Ti}^{2+}, \mathrm{Co}^{2+}$
• C. $\mathrm{Fe}^{3+}, \mathrm{Cr}^{2+}$
• D. $\mathrm{Ti}^{3+}, \mathrm{Mn}^{2+}$

Hint:

The number of unpaired electrons in transition metal ions depends on their electronic configuration.

Answer 1

The Correct Option is A

To identify the transition metal ion pair with an identical number of unpaired electrons, we must examine the electronic configurations of the provided ions.

1. Determine the ground-state electronic configuration for each ion:
2. Vanadium (V), atomic number 23:
   • Neutral Vanadium (V): \([Ar] 3d^3 4s^2\)
   • For \(V^{2+}\): Electron removal from 4s yields \([Ar] 3d^3\), resulting in 3 unpaired electrons.
3. Cobalt (Co), atomic number 27:
   • Neutral Cobalt (Co): \([Ar] 3d^7 4s^2\)
   • For \(Co^{2+}\): Electron removal from 4s yields \([Ar] 3d^7\), resulting in 3 unpaired electrons.
4. Titanium (Ti), atomic number 22:
   • For \(Ti^{2+}\) (following the same procedure): \([Ar] 3d^2\), with 2 unpaired electrons.
   • For \(Ti^{3+}\): \([Ar] 3d^1\), with 1 unpaired electron.
5. Iron (Fe), atomic number 26:
   • For \(Fe^{3+}\): \([Ar] 3d^5\), with 5 unpaired electrons.
6. Chromium (Cr), atomic number 24:
   • For \(Cr^{2+}\): \([Ar] 3d^4\), with 4 unpaired electrons.
7. Manganese (Mn), atomic number 25:
   • For \(Mn^{2+}\): \([Ar] 3d^5\), with 5 unpaired electrons.

Analysis of these configurations shows that \(V^{2+}\) and \(Co^{2+}\) each possess 3 unpaired electrons. Consequently, the correct pair is:

\(V^{2+}, Co^{2+}\)