Lewis structure of BrF₅
42 valence electrons. Five Br-F single bonds, with one lone pair on Br, so Br has 12 electrons around it (an expanded octet).
Lewis structure
42 valence electronsFormal charges: none
Why this shape
- 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.
- 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.
- The bond dipoles do not cancel in the square pyramidal shape, so BrF₅ is polar.
How to draw it
- Count the valence electrons: Br 7 + 5 × F 7 = 42 valence electrons, 21 pairs.
- Put Br in the middle and join it to the five outer atoms with single bonds.
- Give each outer atom lone pairs until it has an octet (H needs only two electrons), then put any electrons left over on the central atom.
- Result: five Br-F single bonds, with one lone pair on Br, so Br has 12 electrons around it (an expanded octet).
- Formal charge = valence electrons − lone pair electrons − number of bonds. Here: none.
Class 11, Chapter 4 Chemical Bonding and Molecular Structure.
Lewis structure of BrF5: quick answers
How many valence electrons are in BrF5?
Br 7 + 5 × F 7 = 42 valence electrons, 21 pairs.
What are the formal charges in the Lewis structure of BrF5?
Every atom has a formal charge of zero.
How many lone pairs are in the Lewis structure of BrF5?
16 in all, 1 of them on the central Br.