Most Stable Structure

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KMcFarland_2L
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Most Stable Structure

Postby KMcFarland_2L » Wed Nov 25, 2020 2:40 pm

When drawing Lewis structures, what is the best way to know what structure is the most stable, besides using trial and error?

Crystal Pan 2G
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Re: Most Stable Structure

Postby Crystal Pan 2G » Wed Nov 25, 2020 2:47 pm

The most stable lewis structure is the structure with the lowest formal charge. The more electronegative atoms would be more likely to hold the negative formal charge in the molecule.

Marisa Gaitan 2D
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Re: Most Stable Structure

Postby Marisa Gaitan 2D » Wed Nov 25, 2020 2:49 pm

The best way to know when the Lewis structure is most stable is by calculating formal charge for each atom using FC= V-(S/2) where V are the valence electrons on that atom, and S is the number of shared electrons. The most stable lewis structure will have formal charges closest to 0. And it is also important to remember that the sum of the formal charges of the atoms must equal the net formal charge of the molecule. I find myself still having to do some trial and error when playing around with formal charges, so I don't think there is any way to ensure you'll get the right structure on the first go every time.

Kathy_Li_1H
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Re: Most Stable Structure

Postby Kathy_Li_1H » Thu Nov 26, 2020 9:53 am

Hi! The most stable structures often have the lowest formal charge. AKA: it is better for one atom to have a formal charge of -1 and another to have +1 instead of one atom having a formal charge of -2 and the other to have +2. Although the compound ultimately has a charge of zero, the first structure would be considered more stable. Additionally, often times the more electronegative atom will want the negative formal charge more.

ellenulitsky Dis 1I
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Re: Most Stable Structure

Postby ellenulitsky Dis 1I » Thu Nov 26, 2020 10:32 am

To add to the posts above, a triple bond is more stable than a double, and then a double bond is more stable than a single bond. Hope this helps!

MichaelMendozaD1F
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Re: Most Stable Structure

Postby MichaelMendozaD1F » Fri Dec 04, 2020 3:59 pm

is most "stable" the same as most likely or favorable? I believe they are synonymous in these types of problems but I just want to make sure.

Moura Girgis 1F
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Re: Most Stable Structure

Postby Moura Girgis 1F » Fri Dec 04, 2020 10:14 pm

MichaelMendozaD1F wrote:is most "stable" the same as most likely or favorable? I believe they are synonymous in these types of problems but I just want to make sure.


yes, more stable lewis structures also tend to be those with the lower formal charge, so they are more favorable .

Lauren Sarigumba 1K
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Re: Most Stable Structure

Postby Lauren Sarigumba 1K » Sat Dec 05, 2020 12:19 am

The most stable structure is one that has the fewest number of, and smallest magnitude of, formal charges and with the negative formal charges on the more electronegative atoms.

Mikayla James 2A
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Re: Most Stable Structure

Postby Mikayla James 2A » Sat Dec 05, 2020 10:02 am

Hi! Adding onto the comments above, if you end up with two structures that have the same amount of charges on the atoms, then the structure with the negative charge on the most electronegative atom is the more stable one. For example, if you have the structures HCNO, the structures with the lowest charges have either (a) +1 on N and -1 on O or (b) -1 on C and +1 on N. They have the same amount of charges, but the favored structure is (a) because O is more electronegative than C. Hope this helps!

Sophia Spungin 2E
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Re: Most Stable Structure

Postby Sophia Spungin 2E » Sat Dec 05, 2020 3:07 pm

I believe you would attempt to minimize the formal charge, and this often does take trial and error of drawing lewis structures. You can also consider how many bonds and lone pairs an atom would need to have a formal charge of zero and then try to form the lewis structure this way.

Lung Sheng Liang 3J
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Re: Most Stable Structure

Postby Lung Sheng Liang 3J » Sat Dec 05, 2020 5:52 pm

The best way to find the most stable structure is to draw all possible structures and determine the formal charges on each. The structure with the lowest formal charge would be the most stable

Vanessa Perez
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Re: Most Stable Structure

Postby Vanessa Perez » Sat Dec 05, 2020 6:50 pm

The Lewis structure with no charge or Lewis structure with the least amount of atoms with a charge is the most stable.

Shruti Kulkarni 2I
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Re: Most Stable Structure

Postby Shruti Kulkarni 2I » Sat Dec 05, 2020 7:04 pm

The most stable structure will have the lowest formal charge. If there must be a charge, it is most stable if the most electronegative atom holds the negative charge.

Gigi Elizarraras 2C
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Re: Most Stable Structure

Postby Gigi Elizarraras 2C » Sat Dec 05, 2020 7:10 pm

The most stable/favorable structures are those with the lowest formal charge and can be found out by drawing the lewis structure:)

Ralph Zhang 2L
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Re: Most Stable Structure

Postby Ralph Zhang 2L » Sat Dec 05, 2020 7:19 pm

You need to find the formal charge for each atom in the structure, then choose the structure where all of the formal charges are closest to 0.

MichaelMendozaD1F
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Re: Most Stable Structure

Postby MichaelMendozaD1F » Sun Dec 06, 2020 4:28 pm

Moura Girgis 1D wrote:
MichaelMendozaD1F wrote:is most "stable" the same as most likely or favorable? I believe they are synonymous in these types of problems but I just want to make sure.


yes, more stable lewis structures also tend to be those with the lower formal charge, so they are more favorable .


thank you for the response !

Chance Herbert 3A
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Re: Most Stable Structure

Postby Chance Herbert 3A » Sun Dec 06, 2020 4:36 pm

When drawing your Lewis structure, to get the most stable structure, you should choose the structure that minimizes formal charge for each atom in the structure. Formal charge can be calculated by subtracting the sum of the number of nonbonding valence electrons and half the number of bonding electron from the number of valence electrons for the atom of focus. You should optimally have the lowest number and smallest magnitude of formal charges in your most stable structure. Hope this helps!

Madisen Brown -1C
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Re: Most Stable Structure

Postby Madisen Brown -1C » Sun Dec 06, 2020 4:52 pm

The structures with the lowest formal charge are the most stable

Ava Nickman
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Re: Most Stable Structure

Postby Ava Nickman » Sun Dec 06, 2020 4:57 pm

You need to calculate the formal charge of each structure and evaluate based off of that

Aria Movassaghi 1A
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Re: Most Stable Structure

Postby Aria Movassaghi 1A » Sun Dec 06, 2020 10:38 pm

Structures that have the least amount of formal charge are most stable.

Brandon Carris
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Re: Most Stable Structure

Postby Brandon Carris » Tue Dec 15, 2020 6:33 pm

All you have to do is determine the formal charges among the different structures. The one with the lowest value will be the most stable structure.

Ruth Rosales 3D
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Re: Most Stable Structure

Postby Ruth Rosales 3D » Tue Dec 15, 2020 8:36 pm

It is by the formal charge which is found with:

F = VE - Nonbonoding e - (total # e shared in bonds)/2

IshanModiDis2L
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Re: Most Stable Structure

Postby IshanModiDis2L » Tue Dec 15, 2020 9:26 pm

I believe that the most stable structure will have the lowest formal charge, as it tends to be most stable. If it does have a charge, it tends to be that the most electronegative atom holds the most negative charge.

Leo Naylor 2F
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Re: Most Stable Structure

Postby Leo Naylor 2F » Tue Dec 15, 2020 9:29 pm

The original poster mentioned not using trial and error, so in order to save time, while drawing the structure try to make sure that the formal charges are as close to zero as possible. In order to achieve this, you can follow trends like nitrogen forming three bonds, oxygen forming two bonds, and fluorine forming one bond (and so on for other elements in those groups). Hope this helps!


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