Which of the following is the best Lewis dot structure for SF4?

• A. S is the central atom with four single bonds to F atoms and no lone pairs on S.
• B. S is the central atom with four single bonds to F atoms and one lone pair on S.
• C. S is the central atom with five single bonds to F atoms and no lone pairs on S.
• D. S is the central atom with two double bonds to F atoms and two single bonds to F atoms.

Answer: (B)

Verified step by step guidance

1. Step 1: Determine the total number of valence electrons available for SF4. Sulfur (S) has 6 valence electrons, and each fluorine (F) has 7 valence electrons. Since there are 4 fluorine atoms, calculate the total as: \$6 + 4 \times 7$.
2. Step 2: Draw a skeletal structure with sulfur as the central atom bonded to four fluorine atoms using single bonds. Each single bond represents 2 electrons.
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.
4. Step 4: After completing the fluorine octets, place any leftover electrons on the central sulfur atom as lone pairs. This step is crucial because sulfur can have an expanded octet, but the number of electrons must match the total valence electrons calculated.
5. Step 5: Evaluate the Lewis structures given in the problem by comparing the total number of electrons used and the presence of lone pairs on sulfur. The best Lewis structure will have sulfur with four single bonds to fluorine atoms and one lone pair, satisfying the total valence electron count and formal charge considerations.