T-shaped v. Trigonal pyramid

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Ying Yan 1F
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Joined: Fri Aug 02, 2019 12:16 am

T-shaped v. Trigonal pyramid

Postby Ying Yan 1F » Fri Nov 22, 2019 5:17 pm

Just for clarification, T-shaped is 3 atoms with 2 lone pair and trigonal pyramidal is 3 atoms with 1 lone pair, correct? Thanks!

Michelle Chan 1J
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Joined: Thu Jul 25, 2019 12:16 am

Re: T-shaped v. Trigonal pyramid

Postby Michelle Chan 1J » Fri Nov 22, 2019 5:36 pm

Yes, that is correct!

Sanjana Munagala_1j
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Re: T-shaped v. Trigonal pyramid

Postby Sanjana Munagala_1j » Fri Nov 22, 2019 5:45 pm

You can also have a t-shaped molecule when there are 6 total electron density regions. 3 of them being atoms and 3 being lone pairs.

Hope that helps!

Osvaldo SanchezF -1H
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Joined: Wed Sep 18, 2019 12:21 am

Re: T-shaped v. Trigonal pyramid

Postby Osvaldo SanchezF -1H » Fri Nov 22, 2019 9:35 pm

One way to make a distinction between the two is to know that Trigonal pyramid has 4 regions of electron density while, T-shape has 5 regions of electron density or 6 regions of density as it can be formed using 3 lone pairs and 3 atoms.

Nick Fiorentino 1E
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Re: T-shaped v. Trigonal pyramid

Postby Nick Fiorentino 1E » Sat Nov 23, 2019 10:18 pm

T- shaped has a trigonal bipyramidal arrangement, but has 2 lone pairs and 3 bonds (AX3E2). Trigonal pyramid has a tetrahedral arrangement but has one lone pair and 3 bonding pairs (AX3E)

Jessica Tran_3K
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Re: T-shaped v. Trigonal pyramid

Postby Jessica Tran_3K » Sat Nov 23, 2019 10:53 pm

Yes!

Liliana Aguas 3G
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Re: T-shaped v. Trigonal pyramid

Postby Liliana Aguas 3G » Sat Nov 23, 2019 10:56 pm

Yes, I always like to draw the shape of the electron arrangement then cross of the most reasonable atoms (based on repulsion) and then that is usually how you get T-shape or trigonal pyramidal. It's easier when you have a visual.

Brian J Cheng 1I
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Re: T-shaped v. Trigonal pyramid

Postby Brian J Cheng 1I » Sat Nov 23, 2019 11:21 pm

I second the use of a visual aid to determine molecular shape. Sometimes I find it's helpful to visualize a molecule as if each electron density corresponds to a X value in the "AXE" VSEPR notation, then removing X's based on the number of lone pairs there are until the true molecular shape is revealed.

Nicholas_Gladkov_2J
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Re: T-shaped v. Trigonal pyramid

Postby Nicholas_Gladkov_2J » Sat Nov 23, 2019 11:26 pm

Ying Yan 4H wrote:Just for clarification, T-shaped is 3 atoms with 2 lone pair and trigonal pyramidal is 3 atoms with 1 lone pair, correct? Thanks!


T-shaped electron shape is trigonal bipyramidal, so think of that shape, but then replace two atoms with electron lone pairs, to get the molecular shape, so yes, you get T-shaped.

For trigonal pyramidal, the electron shape is tetrahedral, and for the molecular shape, replace one atom with a lone pair, so yes, you get trigonal pyramidal.

You are correct for both.

Nathan Nakaguchi 1G
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Re: T-shaped v. Trigonal pyramid

Postby Nathan Nakaguchi 1G » Sat Nov 23, 2019 11:33 pm

A= central atom, X= bonded atoms, E= lone pairs.

T shape: AX3E2

trigonal pyramid: AX3E


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