The number of nonbonding electron pairs in `O_2`molecule is

Options

A. 2
B. 6
C. 4
D. 8

Answer

To determine the number of nonbonding electron pairs in the O₂ molecule, we can follow these steps:

### Step 1: Determine the total number of electrons in O₂
Oxygen (O) has an atomic number of 8, which means each oxygen atom has 8 electrons. Since O₂ consists of two oxygen atoms, the total number of electrons is:
\[ 8 \text{ (from one O)} + 8 \text{ (from another O)} = 16 \text{ electrons} \]

### Step 2: Write the molecular orbital (MO) configuration for O₂
The molecular orbital configuration for O₂ can be derived from the molecular orbital theory. The order of filling the molecular orbitals for O₂ is as follows:
1. σ1s²
2. σ*1s²
3. σ2s²
4. σ*2s²
5. σ2p_z²
6. π2p_x²
7. π2p_y²
8. π*2p_x¹
9. π*2p_y¹

The configuration can be summarized as:
\[ \sigma 1s^2, \sigma^* 1s^2, \sigma 2s^2, \sigma^* 2s^2, \sigma 2p_z^2, \pi 2p_x^2, \pi 2p_y^2, \pi^* 2p_x^1, \pi^* 2p_y^1 \]

### Step 3: Identify the nonbonding (or antibonding) electrons
Nonbonding electrons are typically found in the antibonding orbitals (denoted with an asterisk). In the case of O₂, the relevant antibonding orbitals are:
- π*2p_x
- π*2p_y

Each of these antibonding orbitals contains one electron:
- π*2p_x has 1 electron
- π*2p_y has 1 electron

### Step 4: Count the nonbonding electron pairs
Since each pair consists of 2 electrons, we can count the nonbonding pairs:
- π*2p_x has 1 electron (not a pair)
- π*2p_y has 1 electron (not a pair)

Thus, there are no complete pairs of nonbonding electrons in O₂, but there are 2 individual nonbonding electrons.

### Conclusion
The total number of nonbonding electron pairs in the O₂ molecule is:
- **0 pairs** (since nonbonding electrons are not paired).

### Final Answer
The number of nonbonding electron pairs in O₂ is **0**.

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