The bond order for a species with the configuration `sigma1s^(2)sigma^(***)1s^(2)sigma2s^(2)sigma^(**)2s^(2)sigma2px^(1)` will be

Options

A. 1
B. `1//2`
C. zero
D. `3//2`

Answer

To find the bond order for the species with the given electronic configuration, we will follow these steps:

### Step 1: Understand the Bond Order Formula
The bond order (BO) can be calculated using the formula:
\[ \text{Bond Order} = \frac{n_b - n_a}{2} \]
where:
- \( n_b \) = number of electrons in bonding molecular orbitals
- \( n_a \) = number of electrons in antibonding molecular orbitals

### Step 2: Identify the Configuration
The given electronic configuration is:
\[ \sigma 1s^2 \sigma^* 1s^2 \sigma 2s^2 \sigma^* 2s^2 \sigma 2p_x^1 \]

### Step 3: Count Electrons in Bonding and Antibonding Orbitals
- **Bonding Molecular Orbitals (MOs)**:
- \( \sigma 1s^2 \) contributes 2 electrons
- \( \sigma 2s^2 \) contributes 2 electrons
- \( \sigma 2p_x^1 \) contributes 1 electron
- Total \( n_b = 2 + 2 + 1 = 5 \)

- **Antibonding Molecular Orbitals (MOs)**:
- \( \sigma^* 1s^2 \) contributes 2 electrons
- \( \sigma^* 2s^2 \) contributes 2 electrons
- Total \( n_a = 2 + 2 = 4 \)

### Step 4: Apply the Values to the Bond Order Formula
Now, substituting the values of \( n_b \) and \( n_a \) into the bond order formula:
\[ \text{Bond Order} = \frac{n_b - n_a}{2} = \frac{5 - 4}{2} = \frac{1}{2} \]

### Step 5: Conclusion
The bond order for the given species is \( \frac{1}{2} \).