angle size

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Tiffanny_Carranza_2D
Posts: 64
Joined: Fri Oct 02, 2020 12:15 am

angle size

Postby Tiffanny_Carranza_2D » Sat Nov 28, 2020 6:23 pm

hello, I wanted to know how did you do sapling hw question 17

I am not sure how to recognize angle size yet, how did you guys figure it out or how did you get yourself to remember?

thank you

shevanti_kumar_1E
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Joined: Wed Sep 30, 2020 9:40 pm
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Re: angle size

Postby shevanti_kumar_1E » Sat Nov 28, 2020 6:30 pm

To figure out the angle size you first have to recognize the shape of the molecule by counting how many regions of electron density.Once you determine the shape you can figure out the angle (linear: 180, trigonal planar: 120, tetrahedral:109.5,trigonal bipyramid: 90 and 120, and octahedral: 90) From there you have to see if there are lone pairs present for the central atom. If there are then the bond angle will be less than the angle of the basic geometry. The chart I attached below is super helpful!
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Jessie Hsu 1C
Posts: 88
Joined: Wed Sep 30, 2020 9:49 pm

Re: angle size

Postby Jessie Hsu 1C » Sat Nov 28, 2020 6:40 pm

For me, the only stuff I memorize is the names of the different shapes and how all angles in a tetrahedral shape are 109.5. For the rest of the shapes, I just go back to freshman geometry days and solve for the angles by dividing 360 by the number of bonds in each plane (x, y, z).

Leyla Anwar 3B
Posts: 89
Joined: Wed Sep 30, 2020 10:03 pm

Re: angle size

Postby Leyla Anwar 3B » Sun Nov 29, 2020 9:56 pm

Jessie Hsu 2A wrote:For me, the only stuff I memorize is the names of the different shapes and how all angles in a tetrahedral shape are 109.5. For the rest of the shapes, I just go back to freshman geometry days and solve for the angles by dividing 360 by the number of bonds in each plane (x, y, z).


How do you know how many are in each plane? By knowing the structure it is? I feel like this specific problem had very weird structures so finding the angles just seems so difficult.

Kyle_Lee_2B
Posts: 49
Joined: Wed Sep 30, 2020 9:42 pm

Re: angle size

Postby Kyle_Lee_2B » Sun Nov 29, 2020 10:01 pm

The way the molecule is drawn in the question will tell you how many are in each plane I believe. For example, the dotted and filled in triangles that connect certain atoms represent away (dotted) and in front (filled in triangles). Thus that is one plane. The other plane is the regular lines in the lewis structure. just research what the lines and triangles and dashed triangles mean in a lewis structure and this will help you understand how the molecule looks like though the lewis structure.

Bai Rong Lin 2K
Posts: 86
Joined: Wed Sep 30, 2020 9:54 pm

Re: angle size

Postby Bai Rong Lin 2K » Sun Nov 29, 2020 10:46 pm

shevanti_kumar_2I wrote:To figure out the angle size you first have to recognize the shape of the molecule by counting how many regions of electron density.Once you determine the shape you can figure out the angle (linear: 180, trigonal planar: 120, tetrahedral:109.5,trigonal bipyramid: 90 and 120, and octahedral: 90) From there you have to see if there are lone pairs present for the central atom. If there are then the bond angle will be less than the angle of the basic geometry. The chart I attached below is super helpful!

I think this was very helpful. Thanks!

Diana Aguilar 3H
Posts: 85
Joined: Wed Sep 30, 2020 9:50 pm

Re: angle size

Postby Diana Aguilar 3H » Sun Nov 29, 2020 10:49 pm

I was also having some trouble with angle size, thanks to everyone for the explanations and the resources to figure this out, it was very helpful!

nayha a 1E
Posts: 95
Joined: Wed Sep 30, 2020 9:54 pm

Re: angle size

Postby nayha a 1E » Sun Nov 29, 2020 10:58 pm

I also follow the general trend shown on the chart above. I find that keeping this chart on hand is extremely helpful.

Jaclyn Schwartz 1I
Posts: 94
Joined: Wed Sep 30, 2020 9:45 pm

Re: angle size

Postby Jaclyn Schwartz 1I » Sun Nov 29, 2020 11:36 pm

To be honest, it's very difficult to memorize the whole chart with bond angles. While you can think it out, it's very difficult and conceptual. My advice would be to find a chart you like and use it.This is one of the charts I use often and it helps me.
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Screen Shot 2020-11-29 at 11.35.28 PM.png

Susan Chamling 1F
Posts: 86
Joined: Wed Sep 30, 2020 9:42 pm

Re: angle size

Postby Susan Chamling 1F » Sun Nov 29, 2020 11:51 pm

I agree with previous replies that having a chart for reference is very helpful. I've found that with time and having completed more exercises, it has become easier to recall what types of shape and angle sizes would be associated with the molecule. Drawing out the molecule can also help.

Jessie Hsu 1C
Posts: 88
Joined: Wed Sep 30, 2020 9:49 pm

Re: angle size

Postby Jessie Hsu 1C » Thu Dec 03, 2020 7:22 am

Leyla Anwar 1C wrote:How do you know how many are in each plane? By knowing the structure it is? I feel like this specific problem had very weird structures so finding the angles just seems so difficult.


In question 17, the structures are essentially the basic structures we have to memorize combined together. I look at each of the atoms individually and the number of bonds it has to determine the shape, and then zoom out to put all of the structures together. By looking at the shapes one by one, it should be easier to figure out which atoms are in what plane and what angles the have!

apurva-3E
Posts: 135
Joined: Wed Sep 30, 2020 9:59 pm

Re: angle size

Postby apurva-3E » Thu Dec 03, 2020 1:42 pm

Consult a chart for the angle size based off of shape and the presence of lone pairs.


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