Bond Angles

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

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Jenna Ortiguerra 4G
Posts: 50
Joined: Sat Aug 17, 2019 12:18 am

Bond Angles

Postby Jenna Ortiguerra 4G » Fri Nov 15, 2019 12:05 am

What is an easy way to memorize/calculate bond angles of a molecule using the shape of their lewis structure?

Justin Sarquiz 2F
Posts: 106
Joined: Fri Aug 30, 2019 12:15 am

Re: Bond Angles

Postby Justin Sarquiz 2F » Fri Nov 15, 2019 11:04 am

If you do a lot of practice, you should have the angles memorized without really focusing solely on the angles. Practicing naming molecular shapes and angles will help you memorize angles without even realizing it.

Sartaj Bal 1J
Posts: 101
Joined: Thu Jul 25, 2019 12:17 am

Re: Bond Angles

Postby Sartaj Bal 1J » Fri Nov 15, 2019 11:07 am

Gaining familiarity with all the aspects of the VSEPR theory chart (electron and molecular geometry, hybridization, and bond angles etc.) would be extremely useful for problem solving in this unit.

Ashley Kim 3F
Posts: 50
Joined: Thu Jul 25, 2019 12:17 am

Re: Bond Angles

Postby Ashley Kim 3F » Fri Nov 15, 2019 11:13 am

I agree with the above posts - as you practice VSEPR related problems and get more exposure to relationships between the shapes and angles, I am sure that you will find yourself having memorized the corresponding angles!

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Joined: Fri Aug 30, 2019 12:15 am
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Re: Bond Angles

Postby KDang_1D » Fri Nov 15, 2019 3:51 pm

109.5 you'll just to memorize, but the others you can tell from their shape.

Trigonal planar has three atoms spread out evenly on a single plane. 360/3 = 120 degrees

Trigonal bipyramidal has 2 axial elements coming out from both sides of the trigonal planar shape, so you should be able to visualize the 90 degrees. Same with octahedral

And then linear is 180 of course!

IScarvie 1E
Posts: 66
Joined: Sat Aug 17, 2019 12:16 am

Re: Bond Angles

Postby IScarvie 1E » Fri Nov 15, 2019 3:56 pm

If you can remember what the shape looks like three-dimensionally, most of the angles (except 109.5) are pretty intuitive. For example, for the trigonal bipyramidal shape in a 3d space, you can see visually where the 90 and 180-degree angles are.

Junwei Sun 4I
Posts: 125
Joined: Wed Oct 02, 2019 12:16 am

Re: Bond Angles

Postby Junwei Sun 4I » Fri Nov 15, 2019 4:09 pm

I agree with the above posts of doing more practice problems.Also if you remember the repulsion strength order in which lone pair - lone pair repulsion is bigger than lone pair - bonding pair repulsion is bigger than bonding pair - bonding pair repulsion it also helps. Since when you draw out the lewis structure you can see lone pairs pushing the bonding pairs closer together such as in water and NH3. O has two lone pairs and therefore the H-O-H bond will be smaller than H-N-H bond in NH3 (N only has one lone pair).

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