Bond Angles

[Nickolas Manipud 1C]

Do we have to know any other specific bond angles beside 90, 120, 180, and 109.5? For example, should we know that a trigonal pyramidal molecule has bond angles of 107 degrees or just that it is less than 109.5?

[An Dang 3F]

I believe you do not have to memorize all the bond angles except for the ones you have listed. Instead, you should just know if the bonds are less than a certain angle due to lone pairs.

[Emma Miltenberger 2I]

I don't think you need to know any other specific angles as long as you know the general trend. For example, I think it would be acceptable to know that a trigonal pyramidal molecule has a bond angle slightly less than 109.5 degrees if you are able to explain why.

[Miguel Velasco 2J]

Know its less than (>109.5) and why (possible lone pairs)

[McKenna disc 1C]

Agreed, I think it's important to note that bond angles will be smaller than expected in species with lone pairs because the lone pair-lone pair repulsion as well as the lone pair-bond repulsion will be stronger than any bond-bond repulsion, and therefore the bonds are forced closer to one another to minimize repulsion.