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Bond angles for T-shaped, see-saw, and square pyramidal

Posted: Wed Nov 21, 2018 4:37 pm
by Andie Jian 1D
I understand that lone pairs push down the bonding pairs leading to smaller bond angles than expected given the VSEPR shape. However, for t-shaped, see-saw, and square pyramidal, I am confused if the lone pairs push on the equatorial bonds, the axial bonds, or both. Therefore, I am also confused on what the approximate bond angles for each would be. For example, for the see-saw shape, would it change the 180 degree bond angle, or the 120 degree bond angle? Also, does a lone pair have a bond angle as well, or is it omitted because bond angles refer to molecular shape only?

Re: Bond angles for T-shaped, see-saw, and square pyramidal

Posted: Wed Nov 21, 2018 8:31 pm
by Brian Cook
Yes, I believe that you're correct in that the lone pairs push the bonds slightly inward, and that the lone pair's don't have their own bond angles. For T-shaped I think we use <90 degrees as the bond angle because we can't say exactly how much it's pushed in, same with seesaw you would have <90 and <120, and with t shaped you'd have <90.

Re: Bond angles for T-shaped, see-saw, and square pyramidal

Posted: Wed Nov 21, 2018 11:51 pm
by Brice McKeown 3D
When there is a see-saw shape, the lone pair is an equatorial lone pair and it therefore repels only the electron pairs in the two axial bonds aka the two that make the 180 degree angle