Which of the following statements correctly describes the Lewis dot structure for the SO_3^{2-} ion?

• A. It has three resonance structures, each with one sulfur-oxygen double bond and two sulfur-oxygen single bonds, and all oxygen atoms carry a lone pair.
• B. It has three single bonds between sulfur and oxygen, and the sulfur atom carries the negative charges.
• C. It has a single structure with three sulfur-oxygen double bonds and no lone pairs on the oxygen atoms.
• D. It has two resonance structures, each with two sulfur-oxygen double bonds and one sulfur-oxygen single bond.

Answer: (A)

Verified step by step guidance

1. Step 1: Determine the total number of valence electrons for the SO_3^{2-} ion. Sulfur (S) has 6 valence electrons, each oxygen (O) has 6 valence electrons, and the 2- charge adds 2 extra electrons. Calculate the sum: \$6 + 3 \times 6 + 2$.
2. Step 2: Draw a skeletal structure with sulfur as the central atom bonded to three oxygen atoms. Connect sulfur to each oxygen with single bonds initially.
3. Step 3: Distribute the remaining valence electrons to complete the octets of the oxygen atoms first, placing lone pairs on oxygens as needed.
4. Step 4: Check the formal charges on each atom. To minimize formal charges, convert some sulfur-oxygen single bonds into double bonds, creating resonance structures where sulfur forms one double bond and two single bonds with oxygen atoms.
5. Step 5: Recognize that there are three resonance structures, each with one S=O double bond and two S–O single bonds, and that all oxygen atoms carry lone pairs to complete their octets.