Bond Angles

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

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Samantha Chung 4I
Posts: 77
Joined: Wed Oct 03, 2018 12:16 am

Bond Angles

Postby Samantha Chung 4I » Fri Nov 16, 2018 1:06 pm

When we say that for example, the bond angle for a bent shaped molecule is less than 120 degrees, how much smaller is it exactly? Is there a way to determine? Or is it influenced by other factors as well?

Esha Harwalkar 3F
Posts: 30
Joined: Fri Sep 28, 2018 12:26 am

Re: Bond Angles

Postby Esha Harwalkar 3F » Fri Nov 16, 2018 1:12 pm

We don't have to know the exact bond angles, just that when a lone pair is added, the other atoms will repel from the lone pair a little more, causing distortions in the bond angles. For example, if we atoms in the plane and then add a lone pair of electrons ABOVE the plane, the atoms will tilt more downwards (away from the lone pair). In the bent shape, the VSEPR fomula is AX2E2, meaning there are 4 total regions of electron density, like in tetrahedral. In tetrahedral, the bond angles are 109.5 degrees, so when 2 of those regions are lone pairs, then the angles actually become a little less than 109.5 degrees, not 120.

Gillian Ward 1F
Posts: 61
Joined: Fri Sep 28, 2018 12:27 am

Re: Bond Angles

Postby Gillian Ward 1F » Fri Nov 16, 2018 1:14 pm

I don't think it is possible to find an exact figure for the bond angles that are, for instance, less than 120 or 109.5. There are only estimates or a range that it could be in.

Nikki Bych 1I
Posts: 60
Joined: Fri Sep 28, 2018 12:16 am

Re: Bond Angles

Postby Nikki Bych 1I » Fri Nov 16, 2018 1:38 pm

I believe that we just have to recognize that when there are lone pairs, the bond angles are depressed. i.e. 3 bonding pairs 1 lone pair, as long as you say bond angles are less than 109.5 degrees because of the lone pier you should be fine.

Janelle Magaling 3L
Posts: 11
Joined: Thu Oct 04, 2018 12:16 am

Re: Bond Angles

Postby Janelle Magaling 3L » Fri Nov 16, 2018 2:36 pm

You would have to search up the exact degree of the angle since it is very particular. I believe for the test you would not need to know the exact angle, just that it is less than the typical given angle degree in an all atom structure.

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