Question

which of the following is the correct lewis dot structure for a molecule with the formula co₃²⁻?

Explanation:

Step1: Count valence electrons

Carbon has 4 valence electrons, each oxygen has 6 valence electrons, and there is a 2 - charge adding 2 more electrons. So total valence electrons = 4+(3×6)+2 = 24.

Step2: Determine central atom

Carbon is the central atom as it is less electronegative than oxygen.

Step3: Distribute electrons

Connect the oxygen atoms to the carbon atom with single bonds first, using 6 electrons (3 single - bonds). Then distribute the remaining 18 electrons as lone - pairs on the oxygen atoms. But to satisfy the octet rule and minimize formal charges, one of the C - O bonds becomes a double bond.
The correct Lewis structure has a carbon atom in the center, double - bonded to one oxygen atom and single - bonded to the other two oxygen atoms, with all atoms having a complete octet and the overall structure having a 2 - charge.

Answer:

The first option (the structure with a central carbon double - bonded to one oxygen and single - bonded to two other oxygens, all atoms with octets and the whole structure in brackets with a 2 - charge) is the correct Lewis Dot structure for $CO_{3}^{2 - }$.