Chemistry Species and Bond Angles

Question

Hello, if someone may help me solve this question on which has a smaller bond angle as shown in the picture below. I don't have enough information to solve this, it would be greatly appreciated if someone may help, thanks!

Answer 1

You have to determine the Lewis structures. The octet rule structure is fine for VSEPR purposes

BrO₄^- is isoelectronic with as SO₄^2- and PO₄^3- It has 4 attachments and no lone pairs, so it looks like CH₄ (tetrahedral) Central angle of 109.5

BrO₃^- has 3 attachments and a lone pair. It is also in the tetrahedral family, but one of the vertices is taken up by the lone pair. As a result it looks like just the tripod part of the tetrahedron (lp not visible) and, like NH₃ is trigonal pyramidal. The bond angles will be slightly less than 109.5.

The minor adjustments of the limited number of VSEPR bond angles are due to the following:

1) lone pairs take up more room than attachments (no nucleus tightening up the electron domain) (This is the case here - the lp squeezes the attachments together)

2) Double and triple bonds take up more room because of the added electrons.

3) Large attachments will push apart and increase the bond angle.

Take care.