The calculated bond order of `O_(2)^(-)` is

Options

A. `2.5`
B. `2.0`
C. `1.5`
D. `1.0`

Explanation

To calculate the bond order of \( O_2^{-} \) (the superoxide ion), we can follow these steps:

### Step-by-Step Solution:

1. **Determine the Total Number of Electrons:**
- The neutral \( O_2 \) molecule has 16 electrons (8 from each oxygen atom).
- The \( O_2^{-} \) ion has one additional electron due to the negative charge.
- Therefore, the total number of electrons in \( O_2^{-} \) is \( 16 + 1 = 17 \).

2. **Use the Bond Order Formula:**
- The bond order can be calculated using the formula:
\[ \text{Bond Order} = \frac{(N_b - N_a)}{2} \]
where \( N_b \) is the number of bonding electrons and \( N_a \) is the number of antibonding electrons.

3. **Fill the Molecular Orbital Diagram:**
- For \( O_2^{-} \), we fill the molecular orbitals according to the Aufbau principle and Hund's rule:
- The molecular orbital filling order for \( O_2 \) is:
- \( \sigma_{1s}^2 \)
- \( \sigma_{1s}^*^2 \)
- \( \sigma_{2s}^2 \)
- \( \sigma_{2s}^*^2 \)
- \( \sigma_{2p_z}^2 \)
- \( \pi_{2p_x}^2 \)
- \( \pi_{2p_y}^2 \)
- \( \pi_{2p_x}^1 \)
- \( \pi_{2p_y}^1 \) (for \( O_2 \))
- For \( O_2^{-} \), we add one more electron to the next available orbital, which is \( \pi_{2p_x} \) or \( \pi_{2p_y} \):
- \( \sigma_{1s}^2 \)
- \( \sigma_{1s}^*^2 \)
- \( \sigma_{2s}^2 \)
- \( \sigma_{2s}^*^2 \)
- \( \sigma_{2p_z}^2 \)
- \( \pi_{2p_x}^2 \)
- \( \pi_{2p_y}^2 \)
- \( \pi_{2p_x}^1 \) (added electron)
- Total bonding electrons = 10 (from \( \sigma_{2p_z}^2 \), \( \pi_{2p_x}^2 \), and \( \pi_{2p_y}^2 \))
- Total antibonding electrons = 7 (from \( \sigma_{1s}^*^2 \), \( \sigma_{2s}^*^2 \))

4. **Calculate the Bond Order:**
- Using the values from the molecular orbital filling:
\[ \text{Bond Order} = \frac{(10 - 7)}{2} = \frac{3}{2} = 1.5 \]

### Final Answer:
The bond order of \( O_2^{-} \) is **1.5**.