Question

Whay is that $S{F}_4$ molecule , the lone pair of $e^{⊝}$. occupy equatorial positions in preference to axial position? What is the shape of the molecule.

Answer 1

$S$ atom in $S{F}_4$ molecule has 4 bond pairs and one lone pair of electrons. Electron pair geometry is trigonal bipyramidal and molecular geometry is see-saw. The lone pair of electron occupies equatorial position preferentially as it gets less repulsion with bond pair of electrons.

If the lone pair of electrons is in equatorial position, then it forms an angle of approximately ${120}^o$ with equatorial bond pair of electrons. But if the lone pair of electrons is in axial position, then it forms an angle of approximately ${90}^o$ with equatorial bond pair of electrons. Greater is the bond angle, lesser is the repulsion between lone pair and bond pair of electrons.