Bond order of `Be_2` is

Options

A. 1
B. 2
C. 3
D. 0

Answer

To calculate the bond order of the molecule \( Be_2 \), we can follow these steps:

### Step 1: Determine the Electron Configuration
The total number of electrons in \( Be_2 \) is 4 (2 from each beryllium atom).

### Step 2: Fill the Molecular Orbitals
The molecular orbitals for \( Be_2 \) are filled in the following order:
1. \( \sigma_{1s} \)
2. \( \sigma_{1s}^* \) (anti-bonding)
3. \( \sigma_{2s} \)
4. \( \sigma_{2s}^* \) (anti-bonding)

Since \( Be \) has 4 electrons, we fill the molecular orbitals as follows:
- \( \sigma_{1s} \): 2 electrons (bonding)
- \( \sigma_{1s}^* \): 2 electrons (anti-bonding)
- \( \sigma_{2s} \): 0 electrons (not filled)
- \( \sigma_{2s}^* \): 0 electrons (not filled)

### Step 3: Count the Electrons in Bonding and Anti-Bonding Orbitals
- **Bonding Electrons**: 2 (from \( \sigma_{1s} \))
- **Anti-Bonding Electrons**: 2 (from \( \sigma_{1s}^* \))

### Step 4: Calculate the Bond Order
The bond order can be calculated using the formula:
\[ \text{Bond Order} = \frac{(\text{Number of bonding electrons} - \text{Number of anti-bonding electrons})}{2} \]
Substituting the values:
\[ \text{Bond Order} = \frac{(2 - 2)}{2} = \frac{0}{2} = 0 \]

### Conclusion
The bond order of \( Be_2 \) is 0, indicating that there is no stable bond formed between the two beryllium atoms.

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