Molecular Shape Patterns

(Polar molecules, Non-polar molecules, etc.)

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Sara Sadrolsadat 1G
Posts: 39
Joined: Fri Sep 28, 2018 12:16 am

Molecular Shape Patterns

Postby Sara Sadrolsadat 1G » Sun Nov 18, 2018 8:45 pm

When it comes to determining molecular shapes of formulas, must we memorize the conditions of each shape, or are there any patterns or trends in molecular shapes that we can look to to help us determine them, without necessarily having to memorize each shape independently?

Isabelle Fontanilla 1I
Posts: 60
Joined: Fri Sep 28, 2018 12:19 am

Re: Molecular Shape Patterns

Postby Isabelle Fontanilla 1I » Sun Nov 18, 2018 9:02 pm

I think we pretty much have to memorize the conditions for each shape. Making use of the VSEPR notation helps a lot, but it still requires that you know the conditions of each shape. As for trends, I am not aware of any existing.

Bruce Chen 2H
Posts: 60
Joined: Fri Sep 28, 2018 12:26 am

Re: Molecular Shape Patterns

Postby Bruce Chen 2H » Sun Nov 18, 2018 9:58 pm

Unfortunately, there doesn't seem to be a pattern. I think we just have to memorize it at this point.

Yvonne Du
Posts: 64
Joined: Fri Sep 28, 2018 12:23 am

Re: Molecular Shape Patterns

Postby Yvonne Du » Sun Nov 18, 2018 10:00 pm

I think in the lecture we went over some notations about the VSEPR model:
A=central atom
X=bonded atom
E=lone pair

For example, AX3 is trigonal planar, AX2E2 is bend, AX4 is tetrahedral, AX4E is trigonal bipyramidal, and AX4E2 is Square planer.

I think remembering these can save you some time.

Hope this helps.

Sapna Ramappa 1J
Posts: 63
Joined: Fri Sep 28, 2018 12:24 am

Re: Molecular Shape Patterns

Postby Sapna Ramappa 1J » Mon Nov 19, 2018 8:17 am

Unfortunately, I think we just have to purely memorize the different shapes and the names of them. However, if you're a visual learner, there are a bunch of helpful charts online that helped me! Here's one: https://chemstuff.co.uk/academic-work/a ... molecules/

JiangJC Dis2K
Posts: 72
Joined: Fri Oct 12, 2018 12:16 am

Re: Molecular Shape Patterns

Postby JiangJC Dis2K » Mon Nov 19, 2018 8:34 am

I think we basically just need to memorize all of them, though some of the angles could probably be determined by visualizing. There are a lot of shapes, but what helped me was to make an organized table of the formulas using the VSEPR notation of A, X, and E and then the shape, bond angle(s), and hybridization (once we go over that). If you study the table and formulas, it does kind of become a patter because, say, if the test gave you CH5, you would be able to see that as AB5 and label it as trigonal bipyramidal.


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