`COCl_(2)` is a poisonous gas. The formal charge on O atom is

Answer

To calculate the formal charge on the oxygen atom in the molecule COCl₂ (phosgene), we can follow these steps:

### Step 1: Identify the Valence Electrons
- Oxygen (O) is in group 16 of the periodic table, so it has **6 valence electrons**.

### Step 2: Determine Non-bonding Electrons
- In COCl₂, the oxygen atom has **2 lone pairs** of electrons. Each lone pair consists of **2 electrons**, so:
- Non-bonding electrons = 2 pairs × 2 electrons/pair = **4 non-bonding electrons**.

### Step 3: Count Bonding Electrons
- The oxygen atom is bonded to one carbon atom (C) in COCl₂. A single bond consists of **2 electrons**. Therefore:
- Bonding electrons = **2 bonding electrons** (from the C=O bond).

### Step 4: Apply the Formal Charge Formula
- The formula for calculating formal charge (FC) is:
\[ \text{Formal Charge} = \text{Valence Electrons} - \text{Non-bonding Electrons} - \frac{\text{Bonding Electrons}}{2} \]
- Plugging in the values we have:
\[ \text{Formal Charge} = 6 - 4 - \frac{2}{2} \]
\[ \text{Formal Charge} = 6 - 4 - 1 = 1 \]

### Step 5: Conclusion
- The formal charge on the oxygen atom in COCl₂ is **1**.