Bond angles

[Isaias Gomez D3A]

How does one determine the bond angles present, if the VSEPR model only provides qualitative distortions?

[Eve Gross-Sable 1B]

Hi! I think the primary tool we are supposed to use for determining bond angles are the shapes from the formulas that Lavelle has been talking about. Based on those formulas, there is a pretty definitive set for bond angles, which are still approximations but it's my those angular approximations can be generalized based on the formula.

[Nathan Lao 2B]

I don't think we'll have to know the specific angles. Those are usually determined experimentally.
It's more about predicting a smaller/bigger bond angle relative to its VSEPR structure. (For example, NH3 has slightly smaller bond angles than 109.5 since the lone pair exerts a higher repulsion than a bonding pair)

[Zach Richardson 2f]

I believe that the bond angles are experimentally determined, and aren't calculated from VSEPR. The only way we know of to determine them is experimentally.

[Vince Li 2A]

Dr. Lavelle made sure to mention that we don’t need to know the exact bond angles. He just said to make sure that we know if the bond angles of one molecule are greater or less than another molecule. For example, knowing that the bond angle of a tetrahedral atomic shape is 109.5, if given a molecule such as NH3, we should know that due to the lone pair on N, it will cause the molecule to have a bond angle between the hydrogen atoms to be less than 109.5. Put simply, just know the general trends.

[Alex Benson]

I believe that we would only need to know the bond angles that are typically given with the vsepr model, so it would be something memorized.

[Leyla Anwar 3B]

Given that Lavelle has said we don't need to really know but to have the general understanding, especially with basic angles that we see a lot, like 109.5, how did you all solve #17 on sapling (asking for the bond angles of the C3H4 diagrams)? I don't really understand how to do it.

[705383815]

You can determine whether or not the bond angles are larger and smaller than the ones listed with quantitative certainty by noting if the given molecule has unpaired electrons. If it does, then the bond angles are smaller and are more compressed than the fully-bonded models.

[Maryeli Garay 2H]

I don’t think we have to know exact bond angles, I think we just need to be able to decipher if a given angle is bigger or smaller than those around it or compared to another molecule.