Bond Angles (<109 or 104.5, etc)

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

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Samantha Lee 1A
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Bond Angles (<109 or 104.5, etc)

Postby Samantha Lee 1A » Thu Nov 19, 2020 8:52 am

When we are listing the bond angles on an exam, it is okay to just say it is less than a certain angle or do we have to know the specific bond angle? For example, less than 109 degrees or 104.5 degrees.

Benjamin_Hugh_3F
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Re: Bond Angles (<109 or 104.5, etc)

Postby Benjamin_Hugh_3F » Thu Nov 19, 2020 9:07 am

I think it depends on what the questions ask for, but at least in high school, as long as our answers were in a certain range, it was fine. However, I still think It's always better to just memorize the exact/approx values just in case.

Megan Hulsy 1A
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Re: Bond Angles (<109 or 104.5, etc)

Postby Megan Hulsy 1A » Thu Nov 19, 2020 9:12 am

I think Lavelle wants us to understand that we don't need to memorize the exact value of the bond angle, but rather that it's less than 109.5. In high school, we were required to memorize the exact bond angles, but I believe for now we're supposed to apply our knowledge to understanding the different angles based on if its in a certain range, or in this case, less than 109.5.

Ryan_Page_1J
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Re: Bond Angles (<109 or 104.5, etc)

Postby Ryan_Page_1J » Thu Nov 19, 2020 9:27 am

He mentioned in lectures that it is not necessarily important to memorize/calculate these bond angles, but rather be able to predict how they change depending on structure.

Brandon Le 3C
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Re: Bond Angles (<109 or 104.5, etc)

Postby Brandon Le 3C » Thu Nov 19, 2020 1:07 pm

I feel like knowing the exact angles won't be necessary. I think what's more important is understanding the concepts behind the difference in angles and how certain structures affect them and their complications on the molecule.

Mary Shih 3J
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Re: Bond Angles (<109 or 104.5, etc)

Postby Mary Shih 3J » Thu Nov 19, 2020 6:21 pm

if there is an e- repulsion that causes an angle to be less than 109, you can just write your answer as <109 because Lavelle said we don't need to know the exact angle (104.5) and because we don't know how to calculate it in this class.

Shrinidhy Srinivas 3L
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Re: Bond Angles (<109 or 104.5, etc)

Postby Shrinidhy Srinivas 3L » Fri Nov 20, 2020 9:44 am

I think that for trigonal pyramidal, you just need to remember that the bond angle will be slightly less than 109.5 degrees but the exact measurement varies depending on the molecule. I don't think Lavelle expects us to know the exact bond angles. Hope this helps!

Maya Johnson 2a
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Re: Bond Angles (<109 or 104.5, etc)

Postby Maya Johnson 2a » Fri Nov 20, 2020 2:48 pm

I believe we just have to know that it would be less than a certain value, and not a specific value.

Madison Muggeo 3H
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Re: Bond Angles (<109 or 104.5, etc)

Postby Madison Muggeo 3H » Fri Nov 20, 2020 7:29 pm

I believe we should know the relationship between bond angles and lone pair electrons on the central atom. We were never taught how to calculate them, so we will not need to know the exact number, just an approximation based on the structure.


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