Numford
Hybridisation

Hybridisation of BrF₅

Br is sp³d² hybridised (hybridization by the VSEPR count): 5 sigma bonds and 1 lone pair give a square pyramidal shape, bond angle about 85°.

FFBrFFF
  • Br
  • F
  • lone pair

BrF₅Bromine pentafluoride

Square pyramidal

AB₅E: 5 bond pairs, 1 lone pair

  • Hybridisationsp³d²
  • Bond angleabout 85°
  • Polaritypolar

Why this shape

  1. Br has 7 valence electrons. It uses five in five single bonds to F, so two are left as one lone pair.
  2. Steric number = five sigma bonds + one lone pair = 6, so Br is sp³d² hybridised.
  3. Six electron pairs point to the corners of an octahedron (octahedral electron geometry). With one lone pair in place of atoms, the atoms make a square pyramidal shape.
  4. The lone pair takes any one of the six equal positions, and the five bonds form a square pyramid.
  5. The lone pair below the square pushes the four bonds up, so the angle between the top bond and the square is about 85 degrees, a little less than 90.
  6. The bond dipoles do not cancel in the square pyramidal shape, so BrF₅ is polar.

Lewis structure

42 valence electrons
BrFFFFF

Formal charges: none

Working

Why this hybridisation and shape

  1. Br has 7 valence electrons. It uses five in five single bonds to F, so two are left as one lone pair.
  2. Steric number = five sigma bonds + one lone pair = 6, so Br is sp³d² hybridised.
  3. Six electron pairs point to the corners of an octahedron (octahedral electron geometry). With one lone pair in place of atoms, the atoms make a square pyramidal shape.
  4. The lone pair takes any one of the six equal positions, and the five bonds form a square pyramid.
  5. The lone pair below the square pushes the four bonds up, so the angle between the top bond and the square is about 85 degrees, a little less than 90.
  6. The bond dipoles do not cancel in the square pyramidal shape, so BrF₅ is polar.

Class 11, Chapter 4 Chemical Bonding and Molecular Structure.

Questions

Hybridisation of BrF5: quick answers

What is the hybridisation of BrF5?

Br has 7 valence electrons. It uses five in five single bonds to F, so two are left as one lone pair. Steric number = five sigma bonds + one lone pair = 6, so Br is sp³d² hybridised.

What is the shape of BrF5 and its bond angle?

Square pyramidal, with a bond angle of about 85 degrees. Six electron pairs point to the corners of an octahedron (octahedral electron geometry). With one lone pair in place of atoms, the atoms make a square pyramidal shape. The lone pair takes any one of the six equal positions, and the five bonds form a square pyramid. The lone pair below the square pushes the four bonds up, so the angle between the top bond and the square is about 85 degrees, a little less than 90.

Is BrF5 polar or non-polar?

Polar. The bond dipoles do not cancel in the square pyramidal shape, so BrF₅ is polar.

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