I3- Molecular Shape

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Mario Reyes 1C
Posts: 45
Joined: Fri Apr 06, 2018 11:04 am

I3- Molecular Shape

Postby Mario Reyes 1C » Mon May 28, 2018 2:07 pm

Why is I3- linear and not bent? Would the 3 lone pairs on the central atom not cause the molecule to have a bent shape?

Alma Flores 1D
Posts: 64
Joined: Wed Nov 08, 2017 3:01 am

Re: I3- Molecular Shape

Postby Alma Flores 1D » Mon May 28, 2018 2:59 pm

The lewis structure for I3- has two iodines attached to the central iodine and three lone pairs on the central iodine. This gives you 5 regions of electron density around the central atom. This is a trigonal bipyramidal shape. The electron pairs repel each other to maximize their distance from one another, so they take up equatorial positions 120 degrees from one another. The two other iodines are 180 from one another. This gives us a linear shape for AX2E3 (2 bonding pairs and 3 lone pairs).

Ignacio Ramirez 1J
Posts: 31
Joined: Tue Nov 14, 2017 3:02 am

Re: I3- Molecular Shape

Postby Ignacio Ramirez 1J » Tue May 29, 2018 5:53 pm

I3- has three lone pairs in the equatorial position, however, since they are equally spaced they repel the axial I equally, resulting in a linear shape. I3- has 2 bonds and 3 lone pairs for 5 regions of electron density. Placing that into a trigonal bipyramidal structure, the lone pairs go equatorial and the two other I atoms go axial. With the three atoms in a line, the molecule is linear.

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