Numford
Hybridisation

Hybridisation of SF₄

S is sp³d hybridised (hybridization by the VSEPR count): 4 sigma bonds and 1 lone pair give a see-saw shape, bond angle about 102° and 173°.

FFSFF
  • S
  • F
  • lone pair

SF₄Sulphur tetrafluoride

See-saw

AB₄E: 4 bond pairs, 1 lone pair

  • Hybridisationsp³d
  • Bond angleabout 102° and 173°
  • Polaritypolar

Why this shape

  1. S has 6 valence electrons. It uses four in four single bonds to F, so two are left as one lone pair.
  2. Steric number = four sigma bonds + one lone pair = 5, so S is sp³d hybridised.
  3. Five electron pairs point to the corners of a trigonal bipyramid (trigonal bipyramidal electron geometry). With one lone pair in place of atoms, the atoms make a see-saw shape.
  4. The lone pair takes an equatorial position, where it is 90 degrees from only two bond pairs.
  5. The lone pair takes an equatorial position and pushes the bonds away: the equatorial angle closes from 120 to about 102 degrees and the axial bonds bend back from 180 to about 173.
  6. The bond dipoles do not cancel in the see-saw shape, so SF₄ is polar.

Lewis structure

34 valence electrons
SFFFF

Formal charges: none

Working

Why this hybridisation and shape

  1. S has 6 valence electrons. It uses four in four single bonds to F, so two are left as one lone pair.
  2. Steric number = four sigma bonds + one lone pair = 5, so S is sp³d hybridised.
  3. Five electron pairs point to the corners of a trigonal bipyramid (trigonal bipyramidal electron geometry). With one lone pair in place of atoms, the atoms make a see-saw shape.
  4. The lone pair takes an equatorial position, where it is 90 degrees from only two bond pairs.
  5. The lone pair takes an equatorial position and pushes the bonds away: the equatorial angle closes from 120 to about 102 degrees and the axial bonds bend back from 180 to about 173.
  6. The bond dipoles do not cancel in the see-saw shape, so SF₄ is polar.

Class 11, Chapter 4 Chemical Bonding and Molecular Structure.

Questions

Hybridisation of SF4: quick answers

What is the hybridisation of SF4?

S has 6 valence electrons. It uses four in four single bonds to F, so two are left as one lone pair. Steric number = four sigma bonds + one lone pair = 5, so S is sp³d hybridised.

What is the shape of SF4 and its bond angle?

See-saw, with a bond angle of about 102 degrees and 173 degrees. Five electron pairs point to the corners of a trigonal bipyramid (trigonal bipyramidal electron geometry). With one lone pair in place of atoms, the atoms make a see-saw shape. The lone pair takes an equatorial position, where it is 90 degrees from only two bond pairs. The lone pair takes an equatorial position and pushes the bonds away: the equatorial angle closes from 120 to about 102 degrees and the axial bonds bend back from 180 to about 173.

Is SF4 polar or non-polar?

Polar. The bond dipoles do not cancel in the see-saw shape, so SF₄ is polar.

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