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Molecular Shape

Posted: Wed Dec 05, 2018 11:06 pm
by skyeblee2F
IF5 has a VSEPR formula of AX5E but has a square pyramidal shape. Why doesn't it have a trigonal bipyramidal shape? Wouldn't the electron densities be more spaced out this way?

Re: Molecular Shape

Posted: Wed Dec 05, 2018 11:16 pm
by Sarah Fatkin 4I
Hi! IF5 would not have trigonal pyramidal shape because that would mean it would be AX3E (three bonds, one lone pair).

Re: Molecular Shape

Posted: Wed Dec 05, 2018 11:52 pm
by skyeblee2F
sorry, I meant trigonal bipyramidal, not pyramidal

Re: Molecular Shape

Posted: Thu Dec 06, 2018 12:21 am
by Nicolette_Canlian_2L
I believe its geometry comes about because of the lone pair on the iodine. If it were trigonal bipyramidal, there would not be any lone pairs on the central atom.

Re: Molecular Shape

Posted: Thu Dec 06, 2018 12:30 am
by Raymond Ko 1H
The lone pair on the Iodine atom pushes the other atoms down, creating a square pyramidal structure. The structure for an AX5 molecule is trigonal bipyramidal, so removing one of the bonds and replacing it with a lone pair would result in repulsion.