The number of unpaired electrons in `O_(2)` molecule is

Options

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

Answer

To determine the number of unpaired electrons in the O₂ molecule, we can follow these steps:

### Step 1: Determine the Total Number of Electrons
Each oxygen atom has 8 electrons, and since there are two oxygen atoms in O₂, the total number of electrons is:
\[ 8 \text{ (from one O)} + 8 \text{ (from another O)} = 16 \text{ electrons} \]

### Step 2: Fill the Molecular Orbitals According to Molecular Orbital Theory (MOT)
The molecular orbitals for O₂ are filled in the following order:
1. σ(1s) - 2 electrons
2. σ*(1s) - 2 electrons
3. σ(2s) - 2 electrons
4. σ*(2s) - 2 electrons
5. σ(2p_z) - 2 electrons
6. π(2p_x) - 2 electrons
7. π(2p_y) - 2 electrons
8. π*(2p_x) - 1 electron
9. π*(2p_y) - 1 electron

### Step 3: Count the Electrons in Each Molecular Orbital
- σ(1s): 2 electrons
- σ*(1s): 2 electrons
- σ(2s): 2 electrons
- σ*(2s): 2 electrons
- σ(2p_z): 2 electrons
- π(2p_x): 2 electrons
- π(2p_y): 2 electrons
- π*(2p_x): 1 electron
- π*(2p_y): 1 electron

### Step 4: Identify Unpaired Electrons
From the filling of the molecular orbitals, we can see that:
- The π*(2p_x) and π*(2p_y) orbitals each contain 1 electron.
- Therefore, there are 2 unpaired electrons in total.

### Conclusion
The number of unpaired electrons in the O₂ molecule is **2**.