Why does a molecule of `Ne_(2)` fail to exist ?

Answer

To understand why a molecule of Ne₂ (neon dimer) fails to exist, we can analyze the electronic configuration and calculate the bond order. Here’s a step-by-step solution:

### Step 1: Determine the Electronic Configuration of Neon
Neon (Ne) has an atomic number of 10, which means it has 10 electrons. The electronic configuration of neon is:
- 1s² 2s² 2p⁶

### Step 2: Calculate the Total Number of Electrons in Ne₂
Since Ne₂ consists of two neon atoms, the total number of electrons is:
- Total electrons = 10 (from one Ne) × 2 = 20 electrons

### Step 3: Write the Molecular Orbital Configuration for Ne₂
The molecular orbital (MO) theory states that electrons in molecules occupy molecular orbitals that can be bonding or antibonding. For Ne₂, the molecular orbital configuration can be written as:
- σ1s² σ*1s² σ2s² σ*2s² σ2p_z² π2p_x² π2p_y² π*2p_x² π*2p_y² σ*2p_z²

This can be summarized as:
- Bonding orbitals: 10 (σ1s², σ2s², σ2p_z², π2p_x², π2p_y²)
- Antibonding orbitals: 10 (σ*1s², σ*2s², π*2p_x², π*2p_y², σ*2p_z²)

### Step 4: Count the Number of Bonding and Antibonding Electrons
- Bonding electrons = 10
- Antibonding electrons = 10

### Step 5: Calculate the Bond Order
The bond order is calculated using the formula:
\[ \text{Bond Order} = \frac{(\text{Number of Bonding Electrons} - \text{Number of Antibonding Electrons})}{2} \]
Substituting the values:
\[ \text{Bond Order} = \frac{(10 - 10)}{2} = \frac{0}{2} = 0 \]

### Step 6: Conclusion
Since the bond order of Ne₂ is 0, it indicates that there are no net bonding interactions between the two neon atoms. Therefore, a molecule of Ne₂ cannot exist.

### Summary
Ne₂ fails to exist because its bond order is 0, resulting from an equal number of bonding and antibonding electrons.

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