Which of the following has maximum of unpaired d- electrons ?

Options

A. `N^(3+)`
B. `Fe^(2+)`
C. `Zn^(+)`
D. `Cu^+`

Answer

To determine which of the given options has the maximum number of unpaired d-electrons, we will analyze the electronic configurations of the provided species step by step.

### Step 1: Identify the species and their atomic numbers
- **N³⁺**: Atomic number of Nitrogen (N) is 7.
- **Fe²⁺**: Atomic number of Iron (Fe) is 26.
- **Zn⁺**: Atomic number of Zinc (Zn) is 30.
- **Cu⁺**: Atomic number of Copper (Cu) is 29.

### Step 2: Write the electronic configurations
1. **N³⁺**:
- Atomic number = 7
- Electronic configuration of N: \(1s^2 2s^2 2p^3\)
- For N³⁺, we remove 3 electrons from the outermost shell (2p):
- Configuration: \(1s^2 2s^2 2p^0\)
- **d-electrons**: None (0 unpaired d-electrons)

2. **Fe²⁺**:
- Atomic number = 26
- Electronic configuration of Fe: \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^6\)
- For Fe²⁺, we remove 2 electrons from the outermost shell (4s):
- Configuration: \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^0 3d^6\)
- **d-electrons**: 6 (To find unpaired electrons in \(3d^6\), we can use Hund's rule: 4 unpaired electrons)

3. **Zn⁺**:
- Atomic number = 30
- Electronic configuration of Zn: \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10}\)
- For Zn⁺, we remove 1 electron from the outermost shell (4s):
- Configuration: \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^{10}\)
- **d-electrons**: 10 (All paired, so 0 unpaired d-electrons)

4. **Cu⁺**:
- Atomic number = 29
- Electronic configuration of Cu: \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10}\)
- For Cu⁺, we remove 1 electron from the outermost shell (4s):
- Configuration: \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^{10}\)
- **d-electrons**: 10 (All paired, so 0 unpaired d-electrons)

### Step 3: Compare the number of unpaired d-electrons
- **N³⁺**: 0 unpaired d-electrons
- **Fe²⁺**: 4 unpaired d-electrons
- **Zn⁺**: 0 unpaired d-electrons
- **Cu⁺**: 0 unpaired d-electrons

### Conclusion
The species with the maximum number of unpaired d-electrons is **Fe²⁺** with **4 unpaired d-electrons**.

### Final Answer
**Fe²⁺** has the maximum number of unpaired d-electrons.