Which of the following is the correct Lewis dot structure for the SF_3^- ion?

• A. S is the central atom with three double bonds to F atoms and one lone pair on S; each F has two lone pairs; the structure carries a -1 charge.
• B. S is the central atom with three single bonds to F atoms and two lone pairs on S; each F has three lone pairs; the structure carries a -1 charge.
• C. S is the central atom with three single bonds to F atoms and no lone pairs on S; each F has three lone pairs; the structure carries a -1 charge.
• D. S is the central atom with three single bonds to F atoms and one lone pair on S; each F has three lone pairs; the structure carries a -1 charge.

Answer: (D)

Verified step by step guidance

1. Determine the total number of valence electrons available 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 electrons = 6 + (3 × 7) + 1.
2. Place sulfur (S) as the central atom and connect it to the three fluorine atoms with single bonds initially. Each single bond represents 2 electrons.
3. Distribute the remaining electrons to complete the octets of the fluorine atoms first, since fluorine is more electronegative. Each fluorine should have three lone pairs (6 electrons) to complete its octet.
4. Assign any leftover electrons to 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. Verify the formal charges on each atom to confirm the most stable Lewis structure. The structure with sulfur having one lone pair, three single bonds to fluorines each with three lone pairs, and an overall -1 charge is the correct Lewis structure for SF_3^-.