Tetrahedral Bond Angle

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Mrudula Akkinepally
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Joined: Wed Sep 30, 2020 9:31 pm

Tetrahedral Bond Angle

Postby Mrudula Akkinepally » Fri Nov 20, 2020 6:27 pm

Do we need to memorize that a tetrahedral bond angle is 109.5 degrees if all the atoms bonded to the central atom are the same. Dr. Lavelle approximated the bond angle for trigonal pyramidal from the bond angle of tetrahedral.

Malakai Espinosa 3E
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Re: Tetrahedral Bond Angle

Postby Malakai Espinosa 3E » Fri Nov 20, 2020 6:32 pm

I'm not sure how essential it would be to memorize the angles, but I feel like there could be questions dealing with the bond angles on the final? I think it's still helpful to know the bond angles, maybe not exactly the number but their length relative to the other shapes.

Dylan_Nguyen_2C
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Joined: Wed Sep 30, 2020 9:41 pm

Re: Tetrahedral Bond Angle

Postby Dylan_Nguyen_2C » Sat Nov 21, 2020 10:05 pm

I believe Dr. Lavelle said that we don't need to memorize exact bond angles, but we need to know when bond angles differ and the causes for those differences. An example is like how a molecule with a trigonal pyramidal shape(such as SO32-) has smaller angles than a tetrahedral one(like SO42-) because lone pairs exert more repulsion than bonded pairs. Feel free to correct me if I'm wrong though

Neel Bonthala 2G
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Joined: Wed Sep 30, 2020 9:40 pm

Re: Tetrahedral Bond Angle

Postby Neel Bonthala 2G » Sat Nov 21, 2020 10:07 pm

Yes, I think Dylan is correct! It's important to know the order of increasing distortion between regions of electron density. Lone pair-lone pair > lone-pair-bonded pair > bonded pair-bonded pair. So at least know that trigonal pyramidal has a slightly smaller bond angle than tetrahedral due to the repulsion exerted by the lone pair.

805593945
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Joined: Wed Sep 30, 2020 9:36 pm

Re: Tetrahedral Bond Angle

Postby 805593945 » Sat Nov 21, 2020 11:10 pm

I don't think remembering the bonding angle (109.5) is important but knowing how the bonding angle changes depending on the number of lone pairs presence is more important. Lone pair(s) strongly repulse, causing a shift in bonding angle.

Juwan_Madaki_3K
Posts: 87
Joined: Wed Sep 30, 2020 9:33 pm

Re: Tetrahedral Bond Angle

Postby Juwan_Madaki_3K » Wed Nov 25, 2020 1:25 pm

When dealing with shapes like tetrahedral(109.5 degrees) and trigonal planar(120 degrees), those shapes have consistent bond angles, so I feel that it's best to memorize those. However, for shapes like trigonal pyramidal, seesaw, bent, etc., knowing if they're above/below 109.5 or above/below 120 is usually what you need to know.

Crystal Pan 2G
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Re: Tetrahedral Bond Angle

Postby Crystal Pan 2G » Wed Nov 25, 2020 2:58 pm

We should know the approximate angle, ie. greater than, less than 109.5, etc.


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