Which of the following molecules has polar bonds and is non polar?

Question

a) BF3 b) NF3 c) SF4 d) HF e) ICI3

Answer 1

C) has polar bonds but since the S is surronded by F it creates a non-polar molecule

Answer 2

All of these molecules have polar bonds since there is a difference in the electronegativities of the concerned atoms. To deal with matters of polarity, you first have to do a Lewis Dot Structure to find out how many electron pairs are around the central atom and then use VSEPR theory to see what this molecule looks like. Once you have done this, you can draw vectors for the electron attractions and see if they cancel out or are additive. BF3 is linear trigonal (triangular) so the dipoles we draw for electron attractions cancel out and the molecule is non-polar. NF3 is trigonal pyramidal with a lone pair. The electron attraction would be from the N to the F, making the "base" of the triangular pyramid negative leaving the apex at the lone pair with a positive charge. SF4 starts off life as a trigonal bipyramid, but one lone pair would give a see-saw (or distorted tetrahedrion) geometry. Since this is not symetrical, the dipoles wouldn't cancel and the molecule would be polar. HF linear and quite polar. ICl3 starts off as a trigonal bipyramid but has two lone pairs giving a molecular geometry of a T shape and the inequality in electronegativities would make it polar. Sorry for getting too long-winded.

Answer 3

All of the bonds are polar as there is a differnce in electronegativity.