Most Stable Structure
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Most Stable Structure
When drawing Lewis structures, what is the best way to know what structure is the most stable, besides using trial and error?
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Re: Most Stable Structure
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.
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Re: Most Stable Structure
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.
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Re: Most Stable Structure
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.
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Re: Most Stable Structure
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!
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Re: Most Stable Structure
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.
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Re: Most Stable Structure
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 .
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Re: Most Stable Structure
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.
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Re: Most Stable Structure
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!
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Re: Most Stable Structure
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.
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Re: Most Stable Structure
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
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Re: Most Stable Structure
The Lewis structure with no charge or Lewis structure with the least amount of atoms with a charge is the most stable.
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Re: Most Stable Structure
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.
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Re: Most Stable Structure
The most stable/favorable structures are those with the lowest formal charge and can be found out by drawing the lewis structure:)
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Re: Most Stable Structure
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.
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Re: Most Stable Structure
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 !
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Re: Most Stable Structure
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!
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Re: Most Stable Structure
You need to calculate the formal charge of each structure and evaluate based off of that
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Re: Most Stable Structure
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.
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Re: Most Stable Structure
It is by the formal charge which is found with:
F = VE - Nonbonoding e - (total # e shared in bonds)/2
F = VE - Nonbonoding e - (total # e shared in bonds)/2
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Re: Most Stable Structure
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.
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Re: Most Stable Structure
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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