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### Molecular Shape Memorization

Posted: **Fri Nov 24, 2017 5:15 pm**

by **Kyra LeRoy 1E**

For the upcoming test, the shapes/angles are just something to know by memory, correct? Also, does anyone know if there are there specific ones we need to have memorized or just all of them that are mentioned in the textbook?

Thanks!

### Re: Molecular Shape Memorization

Posted: **Fri Nov 24, 2017 10:18 pm**

by **Isabella Sanzi 2E**

I believe that we have to know pretty much all the shapes discussed in class basically going from 2 areas of electron density up to 6 areas of electron density (including variations with lone pairs). And yes, pretty much you have to be able to do the bond angles and shapes from memory, however it is a lot easier and you can work through it if you know the shapes with areas of electron density that are all atoms (linear, trigonal planar, tetrahedral, trigonal bipyramidal, octaheldral) and fill in lone pairs/adjust bond angles as needed.

### Re: Molecular Shape Memorization

Posted: **Fri Nov 24, 2017 11:09 pm**

by **MadisonFuentes1G**

Study the VSEPR shapes that Dr. Lavelle taught in lecture, which can all be found in the beginning of Chapter 4.

### Re: Molecular Shape Memorization

Posted: **Sat Nov 25, 2017 10:51 pm**

by **Aliza Ajmal 1D**

Some of the bond angles are straightforward. For example, trigonal pyramidal has bond angles of 120 degrees (360 degree divided by 3) and linear has bond angles of 180 degrees (360 divided by 2). There are some bond angles that we purely need to memorize, like tetrahedral (bond angle of 109.5 degrees).

I think it's also important to note that there are 3 shapes (trigonal bipyramidal, octahedral, and pentagonal bipyramidal) has different angles along the axial and equatorial planes. A simpler way to say this is they have different horizontal and vertical angles.

### Re: Molecular Shape Memorization

Posted: **Sat Nov 25, 2017 11:18 pm**

by **Connor Kelligrew 2D**

I mean, unless you can memorize the basic shapes and then derive the rest by removing bonds and adding lone pairs of electrons and figure out the bond angle to maximize distance without memory, then yes it would have to simply be memorized.

### Re: Molecular Shape Memorization

Posted: **Sun Nov 26, 2017 12:12 am**

by **Sabrina Fardeheb 2B**

Well, you can memorize them, but I find it very helpful to look at visuals of molecules. Knowing why certain atoms are lower and closer together and understanding the effects of lone pairs on the shape can help if you look at examples. You can also make a chart of the number of regions of electron density and then having the name and bond angles following it. It's a good way to study instead of purely memorizing them.

### Re: Molecular Shape Memorization

Posted: **Sun Nov 26, 2017 12:23 am**

by **tiffanyteguh1C**

I have also found several charts on google that help with memorization like this one below!

https://i.pinimg.com/736x/f9/5d/4e/f95d ... ometry.jpg