Which of the following has maximum number of unpaired electrons ?

Options

A. `Mg^(2+)`
B. `Ti^(3+)`
C. `Fe^(2+)`
D. `Mn^(2+)`

Answer

To determine which of the given ions has the maximum number of unpaired electrons, we will analyze each option step by step.

### Step 1: Analyze Mg²⁺
1. **Atomic Number of Magnesium (Mg)**: 12
2. **Electronic Configuration of Mg**:
- 1s² 2s² 2p⁶ 3s²
3. **Mg²⁺ Configuration**:
- Removing 2 electrons from the outermost shell (3s) gives:
- 1s² 2s² 2p⁶ 3s⁰
4. **Unpaired Electrons**:
- All electrons are paired.
- **Total Unpaired Electrons = 0**

### Step 2: Analyze Ti³⁺
1. **Atomic Number of Titanium (Ti)**: 22
2. **Electronic Configuration of Ti**:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d²
3. **Ti³⁺ Configuration**:
- Removing 3 electrons (2 from 4s and 1 from 3d) gives:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s⁰ 3d¹
4. **Unpaired Electrons**:
- 3d¹ has 1 unpaired electron.
- **Total Unpaired Electrons = 1**

### Step 3: Analyze Fe²⁺
1. **Atomic Number of Iron (Fe)**: 26
2. **Electronic Configuration of Fe**:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶
3. **Fe²⁺ Configuration**:
- Removing 2 electrons (2 from 4s) gives:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s⁰ 3d⁶
4. **Unpaired Electrons**:
- In 3d⁶, the distribution is: ↑↓ ↑↓ ↑↓ ↑ ↑ (4 unpaired electrons).
- **Total Unpaired Electrons = 4**

### Step 4: Analyze Mn²⁺
1. **Atomic Number of Manganese (Mn)**: 25
2. **Electronic Configuration of Mn**:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁵
3. **Mn²⁺ Configuration**:
- Removing 2 electrons (2 from 4s) gives:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s⁰ 3d⁵
4. **Unpaired Electrons**:
- In 3d⁵, the distribution is: ↑ ↑ ↑ ↑ ↑ (5 unpaired electrons).
- **Total Unpaired Electrons = 5**

### Conclusion
- **Mg²⁺**: 0 unpaired electrons
- **Ti³⁺**: 1 unpaired electron
- **Fe²⁺**: 4 unpaired electrons
- **Mn²⁺**: 5 unpaired electrons

**Maximum number of unpaired electrons is in Mn²⁺, which has 5 unpaired electrons.**

### Final Answer:
**Mn²⁺ has the maximum number of unpaired electrons (5).**

---