Bond Angle

[Anand Narayan 1G]

Is there a set degree amount a lone pair causes bond angles to change? I know it lessens the angles, but is there a specific amount?

[Rian Montagh 2K]

No, I believe you have to look up the angles as there isn't a set amount to reduce the angle by. You just know it's slightly less.

[Ibrahim Malik 1H]

With bond angles being repulsed by lone pairs, you won't know the specific amount unless you look up previous experimental values. As for being asked questions on the bond angles, you simply need to know that a lone pair would make the bond slightly less due to repulsion.

[Yousif Jafar 1G]

Like Lavelle said we do not need to memorize the experimental data just that the bond angle is slightly less than what the electron density would suggest.

[305115396]

It is different for every compound so there is no set amount and if there was a set amount it would have to be figured out experimentally

[Christopher Tran 1J]

I learned in high school that, with each additional lone pair, the bond angles are typically reduced by 2.5 degrees from what is suggested by the model. However, as long as you note that the angles are less than the model, that should be fine.

[becca_vandyke_4b]

I don't think you need to know the bond angle. But know that a lone pair lone pair repulsion is greater than a bond pair repulsion.

[Christine Chow 4G]

Why is the axial bond angle of a seesaw molecule less than 180 degrees but the axial bond angle of a T shape molecule is 180 degrees? Does the T shape molecule not also experience electron repulsions from the lone pairs in the equitorial plane?

[RandallNeeDis3K]

Why is the axial bond angle of a seesaw molecule less than 180 degrees but the axial bond angle of a T shape molecule is 180 degrees? Does the T shape molecule not also experience electron repulsions from the lone pairs in the equitorial plane?

The seesaw bond angle is less than 180 because there are 4 bonds and 1 lone pair of e-. That lone pair repels against the bonds making it slightly less than 180 degrees. However, the T shape model is 180 degrees since there are 3 bonds and two lone pairs of e-. Essentially, these too lone pairs cancel out in repulsion, since one is in the "back" of the molecule, and one is in the "front."
Hope this helps!