Seesaw Bond Angles

(Polar molecules, Non-polar molecules, etc.)

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Sara Lakamsani 4D
Posts: 61
Joined: Fri Sep 28, 2018 12:29 am

Seesaw Bond Angles

Postby Sara Lakamsani 4D » Sun Nov 18, 2018 1:11 pm

I'm a little confused about how the lone pair affects the bond angles in the seesaw geometry. Why does the lone pair not affect the 90 and 180 bond angles?

skyeblee2F
Posts: 62
Joined: Fri Sep 28, 2018 12:23 am

Re: Seesaw Bond Angles

Postby skyeblee2F » Sun Nov 18, 2018 1:18 pm

The lone pair does affect the seesaw structure, actually. It pushes the linear pairs away and the trigonal planar pairs closer together. The resulting angles are slightly less than 90º and 120º.

Sara Lakamsani 4D
Posts: 61
Joined: Fri Sep 28, 2018 12:29 am

Re: Seesaw Bond Angles

Postby Sara Lakamsani 4D » Sun Nov 18, 2018 1:26 pm

Ok thanks. From my discussion, I was under the impression that the trigonal planar pairs were affected, but not the linear ones. And also, often, in the textbook, it just says 90 and 120 in the solutions manual for seesaw structures rather than slightly less than 90 and 120. Do you know if it would be correct to say that they are slightly less than the exact angles?

Ryan Troutman 4L
Posts: 68
Joined: Fri Sep 28, 2018 12:22 am

Re: Seesaw Bond Angles

Postby Ryan Troutman 4L » Sun Nov 18, 2018 1:29 pm

My TA said that it's okay to say "Less than 90 degrees or less than 180 degrees" on a test, so I think it's testing our knowledge on the concept that lone pairs alter bond angles.


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