Which statement correctly describes the resonance structures of the carbonate ion, CO_3^{2-}?

• A. All three C–O bonds in CO_3^{2-} are equivalent due to resonance.
• B. Resonance in CO_3^{2-} causes one oxygen atom to carry both negative charges.
• C. CO_3^{2-} has one double bond and two single bonds in its actual structure.
• D. There are only two possible resonance structures for CO_3^{2-}.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand what resonance structures represent. Resonance structures are different Lewis structures for the same molecule that show the delocalization of electrons, especially pi electrons or lone pairs, without changing the positions of atoms.
2. Step 2: Draw the Lewis structures for the carbonate ion, CO_3^{2-}. You will find that there are three resonance structures where the double bond between carbon and oxygen shifts among the three oxygen atoms.
3. Step 3: Recognize that in the resonance hybrid (the actual structure), the electrons are delocalized, meaning the double bond character is spread equally over all three C–O bonds.
4. Step 4: Conclude that because of resonance, all three C–O bonds in CO_3^{2-} are equivalent in length and strength, rather than having distinct single and double bonds.
5. Step 5: Understand that resonance does not localize both negative charges on one oxygen atom, nor does it limit the structure to only two resonance forms; there are three equivalent resonance structures.