### molecular shape and bond angles

Posted:

**Sun Nov 18, 2018 5:24 pm**What molecular shapes do we need to know the exact bond angles of and what molecular shapes do we need know that are less than 120 or 109.5 and not the exact angles?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=41&t=36806

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Posted: **Sun Nov 18, 2018 5:24 pm**

What molecular shapes do we need to know the exact bond angles of and what molecular shapes do we need know that are less than 120 or 109.5 and not the exact angles?

Posted: **Sun Nov 18, 2018 5:29 pm**

When there are lone pairs involved in the molecule, the resulting bond angles will usually be "less than" a specific number, and we don't have to memorize the actual values specifically.

Posted: **Sun Nov 18, 2018 5:34 pm**

I believe we need to know more or less the bond angles for most shapes, but not the actual values of particular molecules. Here is a image of the ideal bond angles of different shapes:

Posted: **Sun Nov 18, 2018 6:27 pm**

I think we just need to know the angles for the basic geometry (electron density geometry) because those values are known and consistent I believe (like 90, 120, 180 degrees). For the electron density geometry, I think we just need to know how the lone pairs affect the bond angles.