Does CO₃²⁻ have resonance structures?

Yes, CO₃²⁻ has 3 resonance structures.

Lewis Structure of CO₃²⁻ (Carbonate Ion)

Q: How do you draw the Lewis structure of CO₃²⁻?

CO₃²⁻ has 24 valence electrons. Carbon is central, bonded to three oxygens. Three single bonds use 6 electrons; 18 remain. Distribute: 3 lone pairs on each O (9 pairs = 18 e⁻). But C only has 6 — not an octet.

What is the Lewis structure of CO₃²⁻?

CO₃²⁻ has 24 valence electrons, 4 bonding electron pairs, and 8 lone pairs. CO₃²⁻ has 24 valence electrons (22 + 2 for the charge). Three equivalent resonance structures exist, each with the double bond on a different C–O. The actual bond order is 1.33.

Lewis structure of CO₃²⁻ (Carbonate Ion)

Formula	CO₃²⁻
Name	Carbonate Ion
Total Valence Electrons	24
Lone Pairs	8
Has Resonance	Yes
Resonance Structures	3
Concept	Polyatomic Ion
Difficulty	Advanced

Step 1: Count Valence Electrons

C has 4, each O has 6, plus 2 for the -2 charge: 4 + 3(6) + 2 = 24.

Step 2: Draw the Skeleton

Carbon is central, bonded to three oxygens. Three single bonds use 6 electrons; 18 remain.

Step 3: Distribute Lone Pairs

Distribute: 3 lone pairs on each O (9 pairs = 18 e⁻). But C only has 6 — not an octet.

Step 4: Form Multiple Bonds

Convert 1 lone pair from one O to form a C=O double bond. C now has 8 electrons.

Step 5: Check Formal Charges

C: FC = 4 - 0 - ½(8) = 0
O (double bond): FC = 6 - 4 - ½(4) = 0
O (single bond): FC = 6 - 6 - ½(2) = -1
Total = 0 + 0 + (-1) + (-1) = -2, matching the ion charge.

Resonance Structures

CO₃²⁻ has 3 resonance structures. The actual electronic structure is a hybrid of all resonance contributors.

Resonance structure 2

Resonance structure 3

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