Bond Angles

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

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JaylinWangDis1L
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Joined: Wed Sep 30, 2020 10:09 pm

Bond Angles

Postby JaylinWangDis1L » Sun Nov 22, 2020 5:34 pm

How do you calculate/approximate bond angles in a given molecule? Thanks!
Last edited by JaylinWangDis1L on Sun Nov 22, 2020 5:40 pm, edited 1 time in total.

Mina Tadros 3L
Posts: 93
Joined: Wed Sep 30, 2020 9:38 pm

Re: Bond Angles

Postby Mina Tadros 3L » Sun Nov 22, 2020 5:36 pm

Bond angles are not calculated. They are experimentally determined.

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

Re: Bond Angles

Postby Kyle Dizon 3A » Sun Nov 22, 2020 5:40 pm

From the knowledge I have gained so far, I believe bond angles are determined experimentally. Bond angles change based on the electron repulsion on the different bonds that are given to us.

Ashley Ko 3I
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Joined: Wed Sep 30, 2020 9:54 pm

Re: Bond Angles

Postby Ashley Ko 3I » Sun Nov 22, 2020 5:46 pm

Hi! I believe you don't need to know how to calculate bond angles. You just need to memorize the general bond angles and be able to determine based on the molecular shape how the bond angle changes. For example, lone pairs decrease the bond angle so for a molecule like H2O, which has 2 lone pairs, the bonding angle would just be less than 109.5 degrees. Hope this helps!

JoshMoore2B
Posts: 90
Joined: Wed Sep 30, 2020 9:51 pm

Re: Bond Angles

Postby JoshMoore2B » Sun Nov 22, 2020 6:25 pm

JaylinWangDis3D wrote:How do you calculate/approximate bond angles in a given molecule? Thanks!


I believe what you are asking here is for your own individual problem solving, so the best advice I can give is to memorize the bond angles between "parent" shapes as well as memorize that adding lone pairs decreases angle size. So, for example, for a tetrahedral shape, the bond angles are 109.5 degrees. Then, if you add lone pairs, you decrease the angle size, so for this tetrahedral the bond angles would be less than 109.5 degrees (<109.5).

In other words, memorize the angles without lone pairs, and then understand that it decreases as you add lone pairs. Hope this helps!

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

Re: Bond Angles

Postby Ansh Patel 2I » Sun Nov 22, 2020 6:32 pm

Hi! As far as I know, bond angles are experimentally determined so we don't have to calculate them. You would just have to remember the angles that go with each different shape.

Sedge Greenlee
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Joined: Wed Sep 30, 2020 9:35 pm

Re: Bond Angles

Postby Sedge Greenlee » Sun Nov 22, 2020 6:35 pm

As Josh said, the best thing you can do is memorize the parent shapes where all bond angles are equal. After this just problem-solve to see if any bond angles would be larger or smaller do due to more/larger areas of electron density.

Astha Patel 2J
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Re: Bond Angles

Postby Astha Patel 2J » Sun Nov 22, 2020 6:50 pm

To reiterate what others have said since bond angles are experimentally determined, I would remember the angles for the parent shapes where all bond angles are equal and then when larger areas of electron density are present then the bond angles would decrease.

sabrina ghalambor 2J
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Re: Bond Angles

Postby sabrina ghalambor 2J » Sun Nov 22, 2020 6:53 pm

as others have said, bond angles are experimentally determined so we don't need to calculate them. however, as long as you can remember the shape of a molecule and how the atoms are arranged, you can probably determine an angle by dividing the number of atoms around the central atom by 360

Keshav Patel 14B 2B
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Re: Bond Angles

Postby Keshav Patel 14B 2B » Sun Nov 22, 2020 6:56 pm

You cannot determine bond angles from any molecular structure. You have to search it up because they are experimentally determined, but you can memorize them.

Becca Nelson 3F
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Joined: Wed Sep 30, 2020 9:52 pm

Re: Bond Angles

Postby Becca Nelson 3F » Sun Nov 22, 2020 8:09 pm

Bond angles in specific molecules are calculated experimentally. We can tell by the structure what the approximate bond angles may be. We also know that lone pairs cause more repulsion, so bond angles away from the lone pair may be smaller. We can not determine to what extent they will be smaller, however, that value is derived experimentally.

Hannah Lechtzin 1K
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Re: Bond Angles

Postby Hannah Lechtzin 1K » Sun Nov 22, 2020 8:10 pm

Bond angles are experimentally determined, so you just have to learn what they are for each different shape. I hope this helps!

Arnav Saud 2C
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Joined: Wed Sep 30, 2020 9:51 pm

Re: Bond Angles

Postby Arnav Saud 2C » Sun Nov 22, 2020 8:20 pm

They're experimentally determined, and generally for usage in class, I think we just need to know the bond angles for the generalized shapes, and then make a prediction on what it'll be based on the general shapes.

Justin Zhang_1A
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Re: Bond Angles

Postby Justin Zhang_1A » Sun Nov 22, 2020 8:33 pm

Bond angles can't be calculated but you can approximate how they'll change based on electron repulsion.

Nicole Bruno Dis 1B
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Re: Bond Angles

Postby Nicole Bruno Dis 1B » Sun Nov 22, 2020 8:43 pm

There's no specific calculation method, but drawing the Lewis structure and determining the number of bonding/nonbonding groups can help determine the geometrical shape and thus the bond angles.

Chudi Onyedika 3A
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Joined: Wed Sep 30, 2020 9:37 pm

Re: Bond Angles

Postby Chudi Onyedika 3A » Sun Nov 22, 2020 9:28 pm

It must be experimentally determined. However, Lewis structures and models can help approximate.

Nathaly Cruz 2D
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Joined: Wed Sep 30, 2020 10:06 pm

Re: Bond Angles

Postby Nathaly Cruz 2D » Sun Nov 22, 2020 9:32 pm

JoshMoore3D wrote:
JaylinWangDis3D wrote:How do you calculate/approximate bond angles in a given molecule? Thanks!


I believe what you are asking here is for your own individual problem solving, so the best advice I can give is to memorize the bond angles between "parent" shapes as well as memorize that adding lone pairs decreases angle size. So, for example, for a tetrahedral shape, the bond angles are 109.5 degrees. Then, if you add lone pairs, you decrease the angle size, so for this tetrahedral the bond angles would be less than 109.5 degrees (<109.5).

In other words, memorize the angles without lone pairs, and then understand that it decreases as you add lone pairs. Hope this helps!


Thank you so much. This really helped me understand how to go about calculating the bond angles in the molecule.

Brandon McClelland3L
Posts: 89
Joined: Wed Sep 30, 2020 9:31 pm

Re: Bond Angles

Postby Brandon McClelland3L » Sun Nov 22, 2020 9:32 pm

You can estimate the bond angle just by measuring. For example, linear is 180, trigonal planar is 120, tetrahedral is 109.5. As everyone else said,the actual bond angle has to be determined experimentally.

Colin Squire 3B
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Joined: Wed Sep 30, 2020 9:35 pm

Re: Bond Angles

Postby Colin Squire 3B » Sun Nov 22, 2020 9:34 pm

They are experimentally determined and based off of relative bond angles. That being said, there is no way to calculate out what the bond angle will be. The best way to determine it is to account for the shape and the lone pairs, then make an assumption from there.

joshtully
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Re: Bond Angles

Postby joshtully » Sun Nov 22, 2020 10:31 pm

Bond angles are experimentally determined rather than calculated.

Nick Saeedi 1I
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Joined: Wed Sep 30, 2020 9:39 pm

Re: Bond Angles

Postby Nick Saeedi 1I » Sun Nov 22, 2020 10:37 pm

I dont think you can calculate them. We just know the relative bond angles based on the structure of the molecule.

Logan Wiedemann 3J
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Joined: Wed Sep 30, 2020 9:59 pm

Re: Bond Angles

Postby Logan Wiedemann 3J » Sun Nov 22, 2020 10:55 pm

They're experimentally calculated, so I don't think we'll have to know them!! Just the basic ones I believe (e.g. angles of a tetrahedral shape)!


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