Question

Account for the following:

SF₆ exists but OF₆ does not.

Answer 1

1. SF₆ exists because sulphur can expand its octet using available d-orbitals (sp³d² hybridisation), allowing coordination with six fluorine atoms in an octahedral shape.
2. OF₆ does not exist because oxygen cannot expand its octet due to lack of d-orbitals; it is limited to a maximum of 8 electrons.
3. Also, oxygen’s high electronegativity and small size restrict it from stabilising six fluorine atoms around it.
4. Hence, SF₆ is stable and known, but OF₆ is not formed due to oxygen’s electronic structure and size limitations.