Write the electronic configuration of (i) Mn4+, (ii) Fe3+ (iii) Cr2+ Mention the number of unpaired electrons in each case.

Answer

To solve the question, we will write the electronic configurations for the ions Mn4+, Fe3+, and Cr2+ and determine the number of unpaired electrons in each case.

### Step 1: Determine the Atomic Number and Electrons
- **Manganese (Mn)** has an atomic number of 25.
- **Iron (Fe)** has an atomic number of 26.
- **Chromium (Cr)** has an atomic number of 24.

Now, we will calculate the number of electrons for each ion based on their oxidation states.

1. **Mn4+**:
- Manganese has 25 electrons.
- Mn4+ means it has lost 4 electrons: 25 - 4 = 21 electrons.

2. **Fe3+**:
- Iron has 26 electrons.
- Fe3+ means it has lost 3 electrons: 26 - 3 = 23 electrons.

3. **Cr2+**:
- Chromium has 24 electrons.
- Cr2+ means it has lost 2 electrons: 24 - 2 = 22 electrons.

### Step 2: Write the Electronic Configurations
Now we will write the electronic configurations for each ion.

1. **Mn4+ (21 electrons)**:
- Configuration:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 3d³
- The outermost shell (3d) has 3 electrons.

2. **Fe3+ (23 electrons)**:
- Configuration:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵
- The outermost shell (3d) has 5 electrons.

3. **Cr2+ (22 electrons)**:
- Configuration:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁴
- The outermost shell (3d) has 4 electrons.

### Step 3: Determine the Number of Unpaired Electrons
Now we will determine the number of unpaired electrons in each case.

1. **Mn4+**:
- 3d³ configuration means there are 3 unpaired electrons.

2. **Fe3+**:
- 3d⁵ configuration means there are 5 unpaired electrons.

3. **Cr2+**:
- 3d⁴ configuration means there are 4 unpaired electrons.

### Final Summary
- **Mn4+**: Electronic Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d³; Unpaired Electrons: 3
- **Fe3+**: Electronic Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵; Unpaired Electrons: 5
- **Cr2+**: Electronic Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁴; Unpaired Electrons: 4