How to Construct the Lewis Formula for SF6

To construct the Lewis formula for SF₆ (sulfur hexafluoride), follow these steps:

1. Determine the total number of valence electrons:
   • Sulfur (S) has 6 valence electrons.
   • Each fluorine (F) atom has 7 valence electrons.
   • Since there are 6 fluorine atoms, the total number of valence electrons from fluorine is 6 × 7 = 42.
   • Adding the valence electrons from sulfur, the total number of valence electrons is 6 + 42 = 48.
2. Place the least electronegative atom in the center:
   • Sulfur is less electronegative than fluorine, so it will be the central atom.
3. Arrange the fluorine atoms around the sulfur atom:
   • Place the 6 fluorine atoms symmetrically around the sulfur atom.
4. Distribute the valence electrons:
   • Start by forming single bonds between sulfur and each fluorine atom. This uses 6 × 2 = 12 electrons.
   • After forming the bonds, you have 48 – 12 = 36 electrons left.
   • Distribute the remaining electrons as lone pairs on the fluorine atoms. Each fluorine atom needs 6 more electrons to complete its octet, so 6 × 6 = 36 electrons are used.
5. Check the octet rule:
   • Sulfur has 12 electrons around it (6 from the bonds and 6 from the lone pairs), which is an exception to the octet rule. Sulfur can have an expanded octet due to its ability to use d-orbitals.
   • Each fluorine atom has 8 electrons (2 from the bond and 6 from the lone pairs), satisfying the octet rule.

The final Lewis structure for SF₆ shows sulfur in the center with six single bonds to fluorine atoms, and each fluorine atom has three lone pairs of electrons.