Q10.26P
Question
Phosgene is a colorless, highly toxic gas employed against troops in World War I and used today as a key reactant in organic syntheses. From the following resonance structures, select the one with the lowest formal charges:
Step-by-Step Solution
VerifiedThe correct option is A which has the lowest formal charge.
A Lewis structure can be defined as the basic structure of a molecule that used the valence electron of each atom involved. In Lewis’s structure, the smallest amountof electronegative atom is going to be the central atom.
Formal Charge is a theoretical concept that is also called fake charge. It is the charge which is dispersed on the whole molecule, not on the single atom.
Formal Charge = Valence electron – Lone pair electron – ½ (Bonded electron)
The octet rule may be defined as the maximum of 8 electronsthat can be filled in an orbital of an atom. It can be completed by sharing or giving the electrons to become stable.
In the structure of phosgene of all three parts, part (A) has a lower formal charge because of the bonding. There is a double bond between the C-atom and O-atom whereas having a single bond between C-atom and 2 Cl-atom which is possible. As O-atom needs 2 electrons and Cl-atom needs 1 electron to fulfill its octet. But in the other two parts (B) and (C) there is a double bond between C-atom and Cl-atom which is difficult to form and needs more energy.