The Lewis structure for SF4 (Sulfur Tetrafluoride) can be drawn by following these steps:
- Determine the total number of valence electrons: Sulfur (S) has 6 valence electrons, and each Fluorine (F) atom has 7 valence electrons. Since there are 4 Fluorine atoms, the total number of valence electrons is 6 + (4 × 7) = 34.
- Place the least electronegative atom in the center: Sulfur is less electronegative than Fluorine, so it will be the central atom.
- Connect the outer atoms to the central atom with single bonds: Draw single bonds between Sulfur and each Fluorine atom. This uses 8 electrons (4 bonds × 2 electrons).
- Distribute the remaining electrons: After forming the single bonds, you have 26 electrons left (34 – 8). Place these electrons around the Fluorine atoms to complete their octets. Each Fluorine atom will have 3 lone pairs (6 electrons).
- Check the octet rule for the central atom: Sulfur has 12 electrons around it (4 from the single bonds and 8 from lone pairs), which is an exception to the octet rule. This is because Sulfur can expand its octet due to the availability of d-orbitals.
The final Lewis structure for SF4 looks like this:
F
|
F — S — F
|
F
In this structure, Sulfur is the central atom with four Fluorine atoms bonded to it. Each Fluorine atom has three lone pairs of electrons, and Sulfur has one lone pair of electrons.