Bond Angles

[Hanniel U 2B]

I know Professor Lavelle mentioned this but do we have to know the bond angles or we just have to guess what it is less than? Also, I'm guessing we have to memorize all the names of shapes right?

[gillianozawa4I]

I think we do have to memorize the bond angles, but they can also be calculated once you have the Lewis structure of the molecule.

[Rachel Dang 1H]

We will most likely have to memorize the names of the shapes. As for bond angles if the central atom has no lone pairs I believe that we can calculate bond angle by dividing 360 the number of central atoms if it's in one plane but other wise we'll have to at the very least know them roughly. And if the central atom has a lone pair the distortion won't be accounted for in VSEPR, and I believe that we don't have anyway of knowing them since they have to be found experimentally.

[Matthew Choi 2H]

The names that you need to know will most likely include: linear, bent, trigonal planar, tetrahedral, trigonal pyramidal, trigonal bipyramidal, seesaw-shaped, T-shaped, octahedral, square pyramidal, and square planar.

The bond angles that you need to know will most likely include: 90, 109.5, 120, 180.

In terms of figuring out if the bond angles are "slightly less" than one of the given bond angles, you need to first figure out if there are lone pairs in the molecule. Keep in mind that lone pairs take up more space than bonds and will push bonds closer together. Imagining models in your head will definitely help you determine the bond angles and shapes.