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Bond Angles

Posted: Sat Nov 16, 2019 6:57 pm
by salvadorramos3k
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?

Re: Bond Angles

Posted: Sat Nov 16, 2019 7:00 pm
by Anish Patel 4B
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.

Re: Bond Angles

Posted: Sat Nov 16, 2019 8:29 pm
by Wilson 2E
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.

Re: Bond Angles

Posted: Sun Nov 17, 2019 12:01 am
by Lauren Stack 1C
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).

Re: Bond Angles

Posted: Sun Nov 17, 2019 1:08 am
by Jillian C 4C
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.

Re: Bond Angles

Posted: Sun Nov 17, 2019 2:44 am
by Alexa Hernandez 3k
You need to know the tendencies of the shape the molecule has, that can and will help a lot ...