Formal charges

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505166714
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Joined: Fri Sep 28, 2018 12:17 am

Formal charges

Postby 505166714 » Thu Nov 08, 2018 10:42 am

I was informed that formal charges are a component of the Lewis structure, do I have to write the formal charges for each of the atoms in the molecule when writing a Lewis structure.

Raymond Ko 1H
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Joined: Fri Sep 28, 2018 12:19 am

Re: Formal charges

Postby Raymond Ko 1H » Thu Nov 08, 2018 10:55 am

Unless specifically instructed to do so, I don't think you need to write the formal charge for each Lewis structure you write. When you are trying to determine which Lewis structure for the particular molecule is most stable and ideal, it may be useful to write the formal charges in order to compare different structures to determine the right one.

Kobe_Wright
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Joined: Fri Sep 28, 2018 12:16 am

Re: Formal charges

Postby Kobe_Wright » Thu Nov 08, 2018 11:20 am

I asked about this in class, you do not need to write the formal charge of each atom in its lewis structure, but if you're checking for resonance you'll need to calculate it and see if there are any alternate structures.

shaunajava2e
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Joined: Fri Sep 28, 2018 12:26 am

Re: Formal charges

Postby shaunajava2e » Thu Nov 08, 2018 11:22 am

formal charges can be used to help determine the most stable lewis structure, however you dont need to explicitly state them unless the questions says so

Stevin1H
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Re: Formal charges

Postby Stevin1H » Thu Nov 08, 2018 12:25 pm

I don't think you would have to write the formal charges for each atom, but it is certainly helpful to do so when determining which lewis structure is the most stable. A formal charge of 0 is the most stable.

Charles Gu 1D
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Joined: Fri Sep 28, 2018 12:16 am

Re: Formal charges

Postby Charles Gu 1D » Thu Nov 08, 2018 9:42 pm

No you don't need to write formal charges, but it'll help you determine whether or not there is a resonance of a more stable structure.

Katie Sy 1L
Posts: 57
Joined: Fri Sep 28, 2018 12:18 am

Re: Formal charges

Postby Katie Sy 1L » Thu Nov 08, 2018 10:52 pm

i don't think it's required unless specified. but i always do because i find it to be super helpful to figure out the most stable form of a molecule

SummerLee1F
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Joined: Fri Sep 28, 2018 12:16 am

Re: Formal charges

Postby SummerLee1F » Sat Nov 10, 2018 10:21 pm

I wouldn’t necessarily write them out unless he asks for it on an exam. If you are doing it to check though, you can always do a short cut way, the equation would be number of valence electrons - sticks & dots. So the number of electrons of one element, minus the sticks and dots drawn around it. Works every time.

Connie Chen 3D
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Joined: Mon Jan 08, 2018 8:12 am

Re: Formal charges

Postby Connie Chen 3D » Sun Nov 11, 2018 2:41 pm

It is not necessary but it is a good way to figure out if your lewis structure can be improved or not. I would do it just in case. If the question asks specifically for you to add the formal charges, then do so, but if not then it is your choice.

Roni Touboul
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Joined: Fri Sep 28, 2018 12:24 am

Re: Formal charges

Postby Roni Touboul » Sun Nov 11, 2018 2:53 pm

If we disregard the formal charges when drawing our lewis structure will it be wrong?

Kathryn Wilhem 1I
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Joined: Fri Sep 28, 2018 12:27 am

Re: Formal charges

Postby Kathryn Wilhem 1I » Sun Nov 11, 2018 2:56 pm

Roni Touboul wrote:If we disregard the formal charges when drawing our lewis structure will it be wrong?

It could possibly be wrong if there is a better lewis structure that will give the most atoms a formal charge of zero, or if an atom that is not as electronegative as another has a negative formal charge. It would be best to calculate the formal charges of each atom to see if you have made the best lewis structure, and if it can be improved, change the structure.

Jaqueline Monreal 2L
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Joined: Fri Sep 28, 2018 12:28 am

Re: Formal charges

Postby Jaqueline Monreal 2L » Sun Nov 11, 2018 4:22 pm

i dont think you have to write it but it should be used to create your structure and make sure you did it correctly and have no extra overall charges (whether positive or negative) in your structure

BenJohnson1H
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Joined: Fri Sep 28, 2018 12:17 am

Re: Formal charges

Postby BenJohnson1H » Sun Nov 11, 2018 4:44 pm

My TA said that points might be marked off if the lewis structure was not accompanied by formal charges on the midterm. I recommend writing them just in case.

Yiting_Gong_4L
Posts: 69
Joined: Fri Sep 28, 2018 12:25 am

Re: Formal charges

Postby Yiting_Gong_4L » Sun Nov 11, 2018 4:51 pm

It might be better to calculate the formal charge of each atom so that you can choose the most stable structure.

Rylee Nelsen 3A
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Joined: Fri Sep 28, 2018 12:22 am

Re: Formal charges

Postby Rylee Nelsen 3A » Sun Nov 11, 2018 5:01 pm

If they are asking for the most stable Lewis structure then the formal charges are necessary but just to be safe I would put them.

Lisa Werner 2F
Posts: 72
Joined: Fri Sep 28, 2018 12:17 am

Re: Formal charges

Postby Lisa Werner 2F » Sun Nov 11, 2018 7:13 pm

usually you do not have to write the formal charge of each atom for points unless instructed to do so, but it will help you find the correct lewis structure by demonstrating which structure will have the lowest energy.


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