Number of antibonding electrons in `O_(2)^(-)` molecular ion is :

Options

A. 8
B. 6
C. 7
D. 4

Explanation

To determine the number of antibonding electrons in the molecular ion \( O_2^- \), we can follow these steps:

### Step 1: Determine the total number of electrons
The molecular ion \( O_2^- \) has 17 electrons. This is because each oxygen atom contributes 8 electrons, and the extra negative charge adds one more electron.

### Step 2: Write the molecular orbital configuration
The molecular orbital (MO) configuration for \( O_2^- \) can be written as follows:
- \( \sigma_{1s}^2 \)
- \( \sigma^*_{1s}^2 \)
- \( \sigma_{2s}^2 \)
- \( \sigma^*_{2s}^2 \)
- \( \sigma_{2p_z}^2 \)
- \( \pi_{2p_x}^2 \)
- \( \pi_{2p_y}^2 \)
- \( \pi^*_{2p_x}^1 \)
- \( \pi^*_{2p_y}^1 \)

### Step 3: Identify the antibonding orbitals
In the molecular orbital theory, the orbitals with a star (∗) symbol are antibonding orbitals. From the configuration, we can see:
- \( \sigma^*_{1s} \)
- \( \sigma^*_{2s} \)
- \( \pi^*_{2p_x} \)
- \( \pi^*_{2p_y} \)

### Step 4: Count the antibonding electrons
Now, we count the electrons in the antibonding orbitals:
- \( \sigma^*_{1s} \): 2 electrons
- \( \sigma^*_{2s} \): 2 electrons
- \( \pi^*_{2p_x} \): 1 electron
- \( \pi^*_{2p_y} \): 1 electron

Adding these together gives us:
\[ 2 + 2 + 1 + 1 = 6 \]

### Conclusion
Thus, the number of antibonding electrons in the \( O_2^- \) molecular ion is **6**.

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