Instructor initials Sulfur hexafluoride Formula: SF6 Lewis Structure (including appropriate resonance forms and formal charges) Number of valence electrons: 48 Electron domain geometry: Octahedral Molecular shape: Octahedral Bond angles: 90 degrees Polarity of individual bonds: Nonpolar Overall polarity of molecule: Nonpolar Hybridization of the central atom: sp3d2
The Correct Answer and Explanation is:
Correct Answer Summary for Sulfur Hexafluoride (SF₆):
- Chemical Formula: SF₆
- Lewis Structure:
Central sulfur (S) atom with six fluorine (F) atoms bonded via single bonds; no lone pairs on S; each F has three lone pairs.
No resonance forms are needed.
Formal charges: 0 on all atoms. - Number of Valence Electrons: 48
- Electron Domain Geometry: Octahedral
- Molecular Shape: Octahedral
- Bond Angles: 90°
- Polarity of Individual Bonds: Polar (due to S–F electronegativity difference)
- Overall Polarity of Molecule: Nonpolar (symmetrical geometry cancels dipoles)
- Hybridization of Central Atom: sp³d²
Explanation
Sulfur hexafluoride (SF₆) is a highly symmetrical molecule with interesting structural and electronic characteristics. To begin, we calculate the total number of valence electrons: sulfur has 6 valence electrons, and each of the six fluorine atoms contributes 7, giving a total of 6+(6×7)=486 + (6 \times 7) = 486+(6×7)=48 valence electrons.
The Lewis structure places sulfur in the center with six single bonds to six fluorine atoms. Each fluorine completes its octet with three lone pairs. Sulfur, as a third-period element, can expand its octet, accommodating 12 electrons (six bonds). There are no formal charges on any atoms in the most stable structure, and no resonance structures are necessary since each F atom is equivalent and forms a single bond.
The electron domain geometry around sulfur is octahedral, based on six bonding pairs and no lone pairs. This leads directly to the molecular shape, which is also octahedral. As a result, bond angles are all 90°, characteristic of octahedral geometry.
Each S–F bond is polar due to fluorine’s high electronegativity. However, the molecule is nonpolar overall because the symmetrical arrangement of identical polar bonds causes dipole moments to cancel out.
The hybridization of the sulfur atom in SF₆ is sp³d², involving one s orbital, three p orbitals, and two d orbitals. This hybridization supports the six sigma bonds needed to form the octahedral shape.
In summary, SF₆ is a nonpolar molecule with polar bonds, an octahedral shape, and expanded octet hybridization. Its structure makes it very stable and inert, explaining its use as an insulator in electrical applications.
