Which of the following statements correctly describes the Lewis dot structure of the SF_3^- ion?

• A. SF_3^- has three single bonds between sulfur and fluorine, one lone pair on sulfur, and a negative formal charge on sulfur.
• B. SF_3^- has three double bonds between sulfur and fluorine, no lone pairs on sulfur, and a negative formal charge on fluorine.
• C. SF_3^- has two single bonds and one double bond between sulfur and fluorine, with two lone pairs on sulfur.
• D. SF_3^- has three single bonds between sulfur and fluorine, no lone pairs on sulfur, and a negative formal charge on fluorine.

Answer: (A)

Verified step by step guidance

1. Step 1: Determine the total number of valence electrons for the SF_3^- ion. Sulfur (S) has 6 valence electrons, each fluorine (F) has 7 valence electrons, and the negative charge adds 1 extra electron. So, total valence electrons = 6 + (3 × 7) + 1.
2. Step 2: Draw the skeletal structure with sulfur as the central atom bonded to three fluorine atoms. Connect each fluorine to sulfur with a single bond initially.
3. Step 3: Distribute the remaining valence electrons to complete the octets of the fluorine atoms first, since fluorine is highly electronegative and typically follows the octet rule strictly.
4. Step 4: Place any leftover electrons on the central sulfur atom as lone pairs. Check the total number of electrons used to ensure it matches the total valence electrons calculated in Step 1.
5. Step 5: Assign formal charges to each atom using the formula: \(\text{Formal charge} = \text{Valence electrons} - \text{Nonbonding electrons} - \frac{1}{2} \times \text{Bonding electrons}\). Confirm that the negative charge is located on sulfur, consistent with the extra electron and the Lewis structure.