Bond Angles

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

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Bond Angles

Postby salvadorramos3k » Sat Nov 16, 2019 6:57 pm

How can you tell when a bond angle is going to get smaller or larger? Also, for example, if the angle gets smaller, how do you know it went from 120 degrees to 109.5? Is this just something I would have to memorize?

Anish Patel 4B
Posts: 59
Joined: Thu Jul 11, 2019 12:17 am

Re: Bond Angles

Postby Anish Patel 4B » Sat Nov 16, 2019 7:00 pm

If there are more lone pairs present, the repulsion that they cause forces the bonding atoms away causing there to be a decrease in bond angle size. Lavelle said you do not need to know the exact numbers but the idea that more lone pair electrons force bonding electrons closer together, decreasing angle size.

Wilson 2E
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Joined: Sat Aug 17, 2019 12:18 am

Re: Bond Angles

Postby Wilson 2E » Sat Nov 16, 2019 8:29 pm

Similarly, molecules that have more atoms will have decreased bond angles as there are more regions of electron density surrounding the central atom making it more cramped.

Lauren Stack 1C
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Joined: Sat Aug 17, 2019 12:18 am

Re: Bond Angles

Postby Lauren Stack 1C » Sun Nov 17, 2019 12:01 am

For each of the different molecular geometry shapes (VSEPR), I am memorizing the possible angles. Otherwise, I believe that is important to understand why an angle might be slightly less than expected (such as 107deg instead of expected 109.5deg) by understanding the role that lone pairs play in repulsion. Further, it is important to compare the different numbers of lone pairs present on the central atom and see the different bond lengths (1 having larger bond angles than 2, etc).

Jillian C 4C
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Joined: Sat Jul 20, 2019 12:16 am

Re: Bond Angles

Postby Jillian C 4C » Sun Nov 17, 2019 1:08 am

A bond angle gets smaller due to lone pairs being stronger in repulsions than bonded atoms. Because the lone electron pairs repel more, there is less space between atoms, causing smaller bond angles.

Alexa Hernandez 3k
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Re: Bond Angles

Postby Alexa Hernandez 3k » Sun Nov 17, 2019 2:44 am

You need to know the tendencies of the shape the molecule has, that can and will help a lot ...

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