Which of the following molecular species has unpaired electrons(s) ? .

Options

A. `N_(2)`
B. `F_(2)`
C. `O_(2)^(-)`
D. `O_(2)^(2-)`

Explanation

To determine which molecular species has unpaired electrons, we will analyze the electron configurations of the given species step by step.

### Step 1: Identify the total number of electrons for each species.
- **Nitrogen (N₂)**: Atomic number = 7, so for N₂:
\[ 7 \times 2 = 14 \text{ electrons} \]
- **Fluorine (F₂)**: Atomic number = 9, so for F₂:
\[ 9 \times 2 = 18 \text{ electrons} \]
- **Oxygen anion (O₂⁻)**: Atomic number = 8, so for O₂:
\[ 8 \times 2 = 16 \text{ electrons} + 1 \text{ (extra electron due to -1 charge)} = 17 \text{ electrons} \]
- **Oxygen (O₂)**: For O₂:
\[ 8 \times 2 = 16 \text{ electrons} \]
- **Oxygen dianion (O₂²⁻)**: For O₂²⁻:
\[ 8 \times 2 = 16 \text{ electrons} + 2 \text{ (extra electrons due to -2 charge)} = 18 \text{ electrons} \]

### Step 2: Write the electron configurations for each species.
- **N₂**:
- Configuration:
\[ 1s^2, 2s^2, 2p^3 \]
- **F₂**:
- Configuration:
\[ 1s^2, 2s^2, 2p^5 \]
- **O₂⁻**:
- Configuration:
\[ 1s^2, 2s^2, 2p^4 \]
- **O₂**:
- Configuration:
\[ 1s^2, 2s^2, 2p^2 \]
- **O₂²⁻**:
- Configuration:
\[ 1s^2, 2s^2, 2p^6 \]

### Step 3: Fill the molecular orbitals and identify unpaired electrons.
1. **N₂**:
- Filling:
\[ 1s^2, 2s^2, 2p^3 \quad \text{(3 electrons in 2p, all paired)} \]
- Unpaired Electrons: 0 (Diamagnetic)

2. **F₂**:
- Filling:
\[ 1s^2, 2s^2, 2p^5 \quad \text{(5 electrons in 2p, all paired)} \]
- Unpaired Electrons: 0 (Diamagnetic)

3. **O₂⁻**:
- Filling:
\[ 1s^2, 2s^2, 2p^4 \quad \text{(4 electrons in 2p, 2 paired, 2 unpaired)} \]
- Unpaired Electrons: 1 (Paramagnetic)

4. **O₂**:
- Filling:
\[ 1s^2, 2s^2, 2p^2 \quad \text{(2 electrons in 2p, 2 unpaired)} \]
- Unpaired Electrons: 2 (Paramagnetic)

5. **O₂²⁻**:
- Filling:
\[ 1s^2, 2s^2, 2p^6 \quad \text{(6 electrons in 2p, all paired)} \]
- Unpaired Electrons: 0 (Diamagnetic)

### Conclusion
The molecular species with unpaired electrons is **O₂⁻** and **O₂**.