VSEPR shape and bond angles

[Taizha 1C]

Hi, I read that molecules with the same VSEPR formula have the same shape, but differ in bond angle. How would I determine the difference between the bond angles in different molecules with the same shape and VSEPR formula? Also how would I be able to recognize the exceptions to this? In the book it gave the example SeCl6^2-.

[Bijal Luhar]

I believe here you would be looking at the strengths of the bonds as a stronger bond would pull closer in one direction and therefore create a smaller angle.

[Hussein Saleh 1L]

Hi, I read that molecules with the same VSEPR formula have the same shape, but differ in bond angle. How would I determine the difference between the bond angles in different molecules with the same shape and VSEPR formula? Also how would I be able to recognize the exceptions to this? In the book it gave the example SeCl6^2-.

I recommend always to draw out the structures first when looking at such a question. Also remember that single bonds are long, double bonds are shorter, and triple bonds are shortest. That may contribute to the answer.

Oh dont forget to determine the shape that helps too!

[Taizha 1C]

Okay, thank you! I believe I understand how to determine the difference now.

[Mariah Guerrero 1J]

Do we have to know the specific bond angles for certain molecular shapes. For example, would it be acceptable to say (on a test) that sulfite ion, SO3 2-, have bond angles less than 109.5? Are approximations ok to state?

[Hussein Saleh 1L]

Do we have to know the specific bond angles for certain molecular shapes. For example, would it be acceptable to say (on a test) that sulfite ion, SO3 2-, have bond angles less than 109.5? Are approximations ok to state?

Yes according to my PLF that is fine.