Determining Bond Angles

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

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Stella Nguyen 1J
Posts: 103
Joined: Wed Sep 30, 2020 9:41 pm

Determining Bond Angles

Postby Stella Nguyen 1J » Sun Nov 29, 2020 7:49 am

Hi everyone!

Whenever a question asks us to determine bond angles, would the bond angles always correspond to the molecular shape? For example, if the molecular shape is linear, the bond angle will always be 180°?

Thank you!

Jessica Katz
Posts: 111
Joined: Wed Sep 30, 2020 10:09 pm
Been upvoted: 2 times

Re: Determining Bond Angles

Postby Jessica Katz » Sun Nov 29, 2020 7:52 am

Yup! that's the only way we can determine the bond angle. And in some cases, we are only required to estimate by saying that the bond angle is going to be less than 109.5 degrees, when otherwise we would have to use the internet to find the exact degree.

Ximeng Guo 2K
Posts: 101
Joined: Wed Sep 30, 2020 9:54 pm

Re: Determining Bond Angles

Postby Ximeng Guo 2K » Sun Nov 29, 2020 8:00 am

Yes we use molecular shapes to determine bond angles.

Kyle Dizon 3A
Posts: 96
Joined: Mon Oct 05, 2020 12:16 am

Re: Determining Bond Angles

Postby Kyle Dizon 3A » Sun Nov 29, 2020 11:15 am

Analyzing the shape will help provide a clear understanding of what the bond angles could possibly be. Directly answering your question, yes, a linear molecular shape has a bond angle of 180 degrees.

Ansh Patel 2I
Posts: 93
Joined: Wed Sep 30, 2020 9:42 pm

Re: Determining Bond Angles

Postby Ansh Patel 2I » Sun Nov 29, 2020 11:21 am

Hi! Yes you're right, the molecular shapes are used to determine bond angles and you just have to memorize what angles correspond to the shapes.

Danielle Goldwirth 3F
Posts: 62
Joined: Wed Sep 30, 2020 10:07 pm

Re: Determining Bond Angles

Postby Danielle Goldwirth 3F » Sun Nov 29, 2020 11:23 am

Exactly!
Trigonal bipyramidal = 90
Tetrahedral = 109.5
Trigonal planar = 120
Linear = 180

Interesting to note is that in Sapling, we had to draw a cyclical 3-carbon ring, and since this forms a triangular shape, the bond angle here would be 60 degrees (the sum of the angles in an equilateral triangle is 180, so dividing that across three angles would give a 60 degree angle).

Justin Lin 1B
Posts: 95
Joined: Wed Sep 30, 2020 9:50 pm

Re: Determining Bond Angles

Postby Justin Lin 1B » Sun Nov 29, 2020 11:32 am

That's correct! The molecular shape of the molecule will give you its bond angles.

Shalyn Kelly 3H
Posts: 84
Joined: Wed Sep 30, 2020 9:55 pm

Re: Determining Bond Angles

Postby Shalyn Kelly 3H » Sun Nov 29, 2020 11:35 am

Are lone pairs what make the bond angles "less than (<) 120" and such? And if there are two lone pairs then the bond angel would be less than less than (<<)?

reyvalui_3g
Posts: 85
Joined: Wed Sep 30, 2020 9:52 pm

Re: Determining Bond Angles

Postby reyvalui_3g » Sun Nov 29, 2020 2:04 pm

Shalyn Kelly 1L wrote:Are lone pairs what make the bond angles "less than (<) 120" and such? And if there are two lone pairs then the bond angel would be less than less than (<<)?

Yes, that is correct, the lone pairs will make the bond angles smaller since they occupy a larger volume of space.

Hannah Lechtzin 1K
Posts: 94
Joined: Wed Sep 30, 2020 9:31 pm

Re: Determining Bond Angles

Postby Hannah Lechtzin 1K » Sun Nov 29, 2020 2:15 pm

Yes! The bond angles are experimentally determined based on molecular shape, so that is how you will determine the bond angle.


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