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 determine the pair of transition metal ions with the same number of unpaired electrons, we need to analyze the electronic configurations of the given ions.

1. First, let's find the electronic configuration for each ion in their ground state:
2. Vanadium (V) has an atomic number of 23:
   • Neutral Vanadium (V): \([Ar] 3d^3 4s^2\)
   • For \(V^{2+}\): remove two electrons from 4s, giving \([Ar] 3d^3\). It has 3 unpaired electrons.
3. Cobalt (Co) has an atomic number of 27:
   • Neutral Cobalt (Co): \([Ar] 3d^7 4s^2\)
   • For \(Co^{2+}\): remove two electrons from 4s, giving \([Ar] 3d^7\). It has 3 unpaired electrons.
4. Titanium (Ti) has an atomic number of 22:
   • For \(Ti^{2+}\) (similar method as above): \([Ar] 3d^2\). It has 2 unpaired electrons.
   • For \(Ti^{3+}\): \([Ar] 3d^1\). It has 1 unpaired electron.
5. Iron (Fe) has an atomic number of 26:
   • For \(Fe^{3+}\): \([Ar] 3d^5\). It has 5 unpaired electrons.
6. Chromium (Cr) has an atomic number of 24:
   • For \(Cr^{2+}\): \([Ar] 3d^4\). It has 4 unpaired electrons.
7. Manganese (Mn) has an atomic number of 25:
   • For \(Mn^{2+}\): \([Ar] 3d^5\). It has 5 unpaired electrons.

By analyzing these configurations, \(V^{2+}\) and \(Co^{2+}\) both have 3 unpaired electrons. Hence, the correct answer is:

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

Answer 2

1. $\mathrm{V}^{2+}$: - $\mathrm{V}^{2+} \Rightarrow 3 \mathrm{~d}^{3} 4 \mathrm{~s}^{0}$ - Number of unpaired electrons = 3
2. $\mathrm{Co}^{2+}$: - $\mathrm{Co}^{2+} \Rightarrow 3 \mathrm{~d}^{7} 4 \mathrm{~s}^{0}$ - Number of unpaired electrons = 3
3. $\mathrm{Ti}^{2+}$: - $\mathrm{Ti}^{2+} \Rightarrow 3 \mathrm{~d}^{2} 4 \mathrm{~s}^{0}$ - Number of unpaired electrons = 2
4. $\mathrm{Fe}^{3+}$: - $\mathrm{Fe}^{3+} \Rightarrow 3 \mathrm{~d}^{5} 4 \mathrm{~s}^{0}$ - Number of unpaired electrons = 5 5. $\mathrm{Cr}^{2+}$: - $\mathrm{Cr}^{2+} \Rightarrow 3 \mathrm{~d}^{4} 4 \mathrm{~s}^{0}$ - Number of unpaired electrons = 4 6. $\mathrm{Ti}^{3+}$: - $\mathrm{Ti}^{3+} \Rightarrow 3 \mathrm{~d}^{1} 4 \mathrm{~s}^{0}$ - Number of unpaired electrons = 1 7. $\mathrm{Mn}^{2+}$: - $\mathrm{Mn}^{2+} \Rightarrow 3 \mathrm{~d}^{5} 4 \mathrm{~s}^{0}$ - Number of unpaired electrons = 5 Therefore, the correct answer is (1) $\mathrm{V}^{2+}, \mathrm{Co}^{2+}$.