Which of the following Lewis dot structure of `CO_2` is incorrect ?

Options

A. `:overset(..)underset(..)O-C-=O:`
B. `overset(..)underset(..)O=C=overset(..)underset(..)O:`
C. `:O-=C-overset(..)underset(..)O:`
D. None of these

Answer

To determine which Lewis dot structure of \( CO_2 \) (carbon dioxide) is incorrect, follow these steps:

### Step 1: Identify the Atoms and Their Valence Electrons
- Carbon (C) has 4 valence electrons.
- Oxygen (O) has 6 valence electrons.
- In \( CO_2 \), there is 1 carbon atom and 2 oxygen atoms.

### Step 2: Calculate Total Valence Electrons
- Total valence electrons = Valence electrons of C + 2 × Valence electrons of O
- Total = \( 4 + 2 \times 6 = 4 + 12 = 16 \) valence electrons.

### Step 3: Determine the Central Atom
- Carbon is less electronegative than oxygen, so carbon will be the central atom, and the two oxygen atoms will be bonded to it.

### Step 4: Draw the Basic Structure
- Start by placing carbon in the center and connecting it to the two oxygen atoms with single bonds. This uses 4 electrons (2 for each bond).

```
O - C - O
```

### Step 5: Distribute Remaining Electrons
- After forming the single bonds, we have \( 16 - 4 = 12 \) electrons left to distribute.
- Place 6 electrons (3 pairs) around each oxygen atom to satisfy the octet rule.

```
:O: - C - :O:
```

### Step 6: Check Octet Rule
- Each oxygen has 8 electrons (6 from lone pairs and 2 from the bond with carbon).
- Carbon has only 4 electrons. To satisfy the octet rule for carbon, we need to form double bonds.

### Step 7: Form Double Bonds
- Convert lone pairs from each oxygen into bonding pairs with carbon to form double bonds.

```
O=C=O
```

### Step 8: Verify Electron Count
- Now, each oxygen has 4 electrons in bonds (2 from the double bond) and 4 from lone pairs, totaling 8.
- Carbon has 8 electrons (4 from the double bonds), satisfying the octet rule.

### Step 9: Analyze the Given Structures
- Review the provided options for Lewis structures of \( CO_2 \):
1. One oxygen with a single bond and 6 electrons, the other with a triple bond.
2. Both oxygens with double bonds.
3. One oxygen with a single bond and 6 electrons, the other with a triple bond.
4. None of these.

### Step 10: Identify the Incorrect Structure
- The structure with both oxygens having double bonds is incorrect because it does not allow for the proper distribution of electrons as per the octet rule for carbon.
- Therefore, the incorrect Lewis dot structure is **Option 2**.

### Final Answer
The incorrect Lewis dot structure of \( CO_2 \) is **Option 2**.

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