Which has maximum number of unpaired `e^(-)` ?

Options

A. Na
B. Mn
C. Cr
D. `Fe^(+3)`

Explanation

To determine which element has the maximum number of unpaired electrons, we will analyze the electronic configurations of the given elements: Sodium (Na), Manganese (Mn), Chromium (Cr), and Iron (Fe³⁺).

### Step 1: Write the electronic configuration for Sodium (Na)
- Sodium has an atomic number of 11.
- The electronic configuration is:
\[ \text{Na: } 1s^2 \, 2s^2 \, 2p^6 \, 3s^1 \]
- **Unpaired electrons**: 1 (from the 3s orbital)

### Step 2: Write the electronic configuration for Manganese (Mn)
- Manganese has an atomic number of 25.
- The electronic configuration is:
\[ \text{Mn: } 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^5 \, 4s^2 \]
- **Unpaired electrons**: 5 (from the 3d orbital)

### Step 3: Write the electronic configuration for Chromium (Cr)
- Chromium has an atomic number of 24.
- The electronic configuration is:
\[ \text{Cr: } 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^5 \, 4s^1 \]
- **Unpaired electrons**: 6 (5 from the 3d orbital and 1 from the 4s orbital)

### Step 4: Write the electronic configuration for Iron (Fe³⁺)
- Iron has an atomic number of 26. The neutral iron configuration is:
\[ \text{Fe: } 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^6 \, 4s^2 \]
- For Fe³⁺, we remove 3 electrons (2 from 4s and 1 from 3d):
\[ \text{Fe}^{3+}: 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^5 \]
- **Unpaired electrons**: 5 (from the 3d orbital)

### Conclusion
Now, let's summarize the number of unpaired electrons for each element:
- Sodium (Na): 1 unpaired electron
- Manganese (Mn): 5 unpaired electrons
- Chromium (Cr): 6 unpaired electrons
- Iron (Fe³⁺): 5 unpaired electrons

The element with the maximum number of unpaired electrons is **Chromium (Cr)** with **6 unpaired electrons**.