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### Bond Angles

Posted: Wed Nov 14, 2018 8:59 am
do we just have to memorize the bond angles for different molecular shapes?

### Re: Bond Angles

Posted: Wed Nov 14, 2018 9:06 am
Yeah, I think we need to memorize bond angles for the major molecular geometry shapes (180, 120, 109.5, 90/120, 90) as you move from linear, trigonal planar, tetrahedral, trigonal bipyramidal, octahedral, and then just put ranges for anything with lone pairs.

Eg. Trigonal planar: 120, but Bent could be between 109.5 and 120 depending on what two atoms you look at.

### Re: Bond Angles

Posted: Wed Nov 14, 2018 10:38 am
some of them are kinda obvious like the 180 and the 120 but the odd ones like the 109.5 for the tetrahedral would be helpful to memorize. my TA was talking about how in past tests all they've asked before was to determine the shape and bond angle so it's probably best to memorize to get easy points if we were asked that too

### Re: Bond Angles

Posted: Wed Nov 14, 2018 11:16 am
We should be able to identify bond angles whether it be for example 180,120, 90 or <120,<90
However we do not need to know the specific bond angle for a specific molecule if it is less than like <120 because the bond angle would vary slightly for each molecule.

### Re: Bond Angles

Posted: Wed Nov 14, 2018 11:28 am
We can calculate them using VSEPR if the central atom has no lone pairs by dividing 360 degrees by how many atoms are bonded to the central atom. However we cannot use this method when they are are lone pairs since VSEPR doesn't account for the distortion that happens when the lone pair and bonded electron pairs interact.