Based on Formal Charges, Draw the Most Preferred Lewis Structure for ClO3

To draw the most preferred Lewis structure for ClO₃^– (chlorate ion) based on formal charges, follow these steps:

1. Count the Total Number of Valence Electrons:
   • Chlorine (Cl) has 7 valence electrons.
   • Each Oxygen (O) has 6 valence electrons.
   • Add one extra electron for the negative charge.
   • Total valence electrons = 7 + (3 × 6) + 1 = 26 electrons.
2. Draw the Skeleton Structure:
   • Place Chlorine (Cl) in the center and surround it with three Oxygen (O) atoms.
   • Connect each Oxygen to Chlorine with a single bond.
3. Distribute the Remaining Electrons:
   • After forming single bonds, 20 electrons remain (26 – 6 = 20).
   • Place lone pairs on the Oxygen atoms to satisfy the octet rule.
   • Each Oxygen will have 3 lone pairs (6 electrons).
4. Calculate Formal Charges:
   • Formal charge = (Valence electrons) – (Non-bonding electrons) – (Bonding electrons / 2).
   • For Chlorine: 7 – 0 – (6 / 2) = +1.
   • For each Oxygen: 6 – 6 – (2 / 2) = -1.
5. Optimize the Structure:
   • To minimize formal charges, form double bonds between Chlorine and one or more Oxygen atoms.
   • By forming one double bond, the formal charge on Chlorine becomes 0, and the formal charge on the double-bonded Oxygen becomes 0.
   • The final structure has one double bond and two single bonds.

The most preferred Lewis structure for ClO₃^– is:

    O
    ||
Cl — O
    |
    O

This structure minimizes formal charges and follows the octet rule, making it the most stable arrangement.