Re: Lewis Structure IBr3


Neil W. wrote:
> Can anyone show me the Lewis Structure (including Geometry) for IBr3. I'm
> trying to help my son with his chemistry, but we can't figure this one out.
> Thanks.

Iodine has 7 electrons. Br's each take one, so that leaves 2 lone pairs
to give everybody 8. Lewis done.

Geometry is tricky. You've got 3 single bonds and 2 lone pairs for a
total of 5, which gives you a structure that looks like two trigonal
pyramids stuck together at the bases. You'd think lone pairs would be
at the pyramid apexes (apices?), but in general lone pairs want all the
space they can get, and they can be 120 degrees appart in the
equatorial position, whereas the angle to the apex is 90 degrees,
right? So picture the two lone pairs out there at two of the three
equatorial positions, and that leaves the bromines hung out in a shape
like a "T." Weird, eh? But that should make the molecule polar, and
these halogen trihalides are indeed all polar molecules. So it works.

SBH

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