VSEPR repulsion model

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Lauren Bui 1E
Posts: 54
Joined: Sat Jul 20, 2019 12:15 am

VSEPR repulsion model

Postby Lauren Bui 1E » Sun Nov 17, 2019 3:29 pm

How does repulsion play a role in the VSEPR model and how is it calculated?

AryaG_4C
Posts: 50
Joined: Mon Sep 30, 2019 12:16 am

Re: VSEPR repulsion model

Postby AryaG_4C » Sun Nov 17, 2019 4:15 pm

VSEPR models takes in repulsion while determining the shape of the molecules and the subsequent angles that the bonds have. In general, repulsion strength follows the rule of:
lone-lone pair>lone-bonding pair>Bonding-Bonding pair

SarahCoufal_1k
Posts: 60
Joined: Thu Jul 25, 2019 12:17 am

Re: VSEPR repulsion model

Postby SarahCoufal_1k » Sun Nov 17, 2019 4:18 pm

As said above, the strength of repulsion would affect the angles, which will also affect the shape. a lone pair lone pair would have greater repulsion and so the bond angle would be larger because they can't get as close to each other

Ayushi2011
Posts: 54
Joined: Wed Feb 27, 2019 12:17 am

Re: VSEPR repulsion model

Postby Ayushi2011 » Sun Nov 17, 2019 4:19 pm

If there is repulsion between lone pairs, it would change the structure of the atom. We need to figure out how the lone pairs need to be arranged in each structure to minimise repulsion and find most stability.

Maika Ngoie 1B
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Joined: Fri Aug 02, 2019 12:16 am

Re: VSEPR repulsion model

Postby Maika Ngoie 1B » Sun Nov 17, 2019 4:39 pm

In a VESPR model, there is repulsion between lone pairs and bonding pairs. In terms of strength, LP--LP Bonds > LP--Bonding > Bonding--Bonding. Because atoms want to be spread out in VESPR models, the lone pairs cause an increased amount of repulsion.

Maika Ngoie 1B
Posts: 58
Joined: Fri Aug 02, 2019 12:16 am

Re: VSEPR repulsion model

Postby Maika Ngoie 1B » Sun Nov 17, 2019 5:15 pm

Bond angles also cannot be calculated, per say, using VESPR, but it can help you determine in in terms of steric numbers. For example, we know that methane (CH4) is a tetrahedral, and all bond angles are 109.5, but ammonia (NH3) which has the same principle shape as methane, except now has a lone pair instead of a 4th bonded atom created the shape trigonal pyramidal. The repulsion of the lone pair causes the angles to become smaller, so the angles for a trigonal pyramidal are about 107, but more importantly it is <109.5.

Kennedi2J
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Joined: Wed Sep 18, 2019 12:20 am

Re: VSEPR repulsion model

Postby Kennedi2J » Sun Nov 17, 2019 5:45 pm

How do you make sure your'e using the correct Lewis structure when estimating the bond angle?

AveryAgosto
Posts: 62
Joined: Wed Sep 18, 2019 12:16 am

Re: VSEPR repulsion model

Postby AveryAgosto » Sun Nov 17, 2019 5:47 pm

Repulsion helps to determine shape and bond angle. The stronger bonds must be further apart.

EvaLi_3J
Posts: 53
Joined: Wed Oct 02, 2019 12:16 am

Re: VSEPR repulsion model

Postby EvaLi_3J » Sun Nov 17, 2019 6:02 pm

Repulsion plays a large role. It determine both the general arrangement of the atoms in molecules and the specific angles between bonds. Repulsion makes it important that electron clouds are located as far from each other as possible.


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