Bond Angles

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

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Tylor McGrew 1J
Posts: 20
Joined: Fri Sep 29, 2017 7:03 am

Bond Angles

Postby Tylor McGrew 1J » Sun Nov 12, 2017 5:20 pm

Why is it that some bond angles are not an exact number, but instead are "slightly less" than a certain example. For instance, why is O3's bond angle slightly less than 120 degrees rather than just 120 degrees?

Janine Chan 2K
Posts: 71
Joined: Fri Sep 29, 2017 7:04 am

Re: Bond Angles

Postby Janine Chan 2K » Sun Nov 12, 2017 5:36 pm

When molecules have lone pairs around the central atom, other bond angles are forced closer together (we won't know the exact angle, but you can see that the bond angles would be a little less than those in a structure without lone pairs). This applies to O3, which has 1 lone pair around the central atom.

Andy Liao 1B
Posts: 52
Joined: Thu Jul 13, 2017 3:00 am

Re: Bond Angles

Postby Andy Liao 1B » Sun Nov 12, 2017 5:42 pm

Whether the bond angle is less or more depends on whether there are lone pairs or not. This is because lone pairs strongly repulse not only each other but also other atoms within the molecules. In the case of O3, the central O has a lone pair and two bonding pairs. The repulsion between the bond pairs is less that the repulsion between a bond pair and the lone pair. As a result, the other two oxygen atoms in the molecule come closer together, making the bond angle less than 120 degrees and slightly distorting the trigonal planar shape.

Ozhen Atoyan 1F
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Joined: Thu Jul 27, 2017 3:01 am
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Re: Bond Angles

Postby Ozhen Atoyan 1F » Sun Nov 12, 2017 5:42 pm

To add on to the previous posts, some bond angles are not an exact number, because they are based on experimental values. The angles form from electron repulsion (lone pairs). The electrons need to have the maximum space apart. Thus, the shapes are formed.

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