What is the formal charge on 'C' atom in the phosgene ($\text{COCl}_2$) molecule?
Show Hint
As a quick conceptual shortcut: whenever a neutral main-group element forms its standard preferred valency number of bonds (like Carbon forming exactly 4 bonds total), its formal charge will always evaluate to zero!
Step 1: Understanding the Question:
We are required to determine the formal charge on the central carbon (C) atom in a molecule where it forms a double bond with oxygen and single bonds with two chlorine atoms.
Step 2: Key Formula or Approach:
The formal charge (FC) of an atom in a Lewis structure is evaluated using the formula:
$$\text{FC} = V - N - \frac{B}{2}$$
Where:
$V =$ Number of valence electrons of the isolated free atom.
$N =$ Number of non-bonding valence electrons (lone pair electrons).
$B =$ Number of bonding electrons (shared electrons).
Step 3: Detailed Explanation:
Let us apply the parameters specifically to the central Carbon atom:
Carbon belongs to Group 14, so its valence electrons are $V = 4$.
In this structure, carbon shares all its valence electrons to complete its octet and has no lone pairs left, so $N = 0$.
Carbon forms a total of 4 covalent bonds (one double bond to O and two single bonds to Cl). Each covalent bond consists of 2 shared electrons, giving $B = 4 \times 2 = 8$ bonding electrons.
Substitute these parameters back into our formal charge formula:
$$\text{FC} = 4 - 0 - \frac{8}{2}$$
$$\text{FC} = 4 - 4 = 0$$
The formal charge on the carbon atom is exactly zero, matching option (D).
Step 4: Final Answer:
The formal charge on the carbon atom is Zero, which corresponds to option (D).
