## Formal charge purpose

$FC=V-(L+\frac{S}{2})$

Moris 1H
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### Formal charge purpose

Why us calculating formal charge important for every Lewis Structure?

Jonghwee Park 1K
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### Re: Formal charge purpose

I think it’s because of the formal charge adds up to 0, the Lewis structure is the most stable.

Heung Ching Chia 1E
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### Re: Formal charge purpose

Yes, it is desirable for molecules to have the lowest energy lewis structure possible so that it can have the most stable structure. The lower the formal charge for the molecule overall and also for the individual atoms themselves, the more stable the structure.

Moris 1H
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### Re: Formal charge purpose

So once you make a basic lewis structure you would have to calculate the formal charges of each atoms in the structure and rearrange electrons to get to 0?

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### Re: Formal charge purpose

If having a formal charge of 0 means that an atom is most stable, then why do atoms like chlorine tend to have a negative charge when isolated (ie Cl-)?

Amanda 1A
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### Re: Formal charge purpose

yes, you would need to find the most stable bonding of that molecule by making the formal charges of the atoms zero or as close to zero as possible

Molly Oakes 1A
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### Re: Formal charge purpose

Making the formal charge as close to zero as possible determines the best Lewis structure.

Caitlyn Ponce 1L
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### Re: Formal charge purpose

Formal charge can also be used to check if your Lewis Structure is correct for charged molecules.

CarinaVargas1J
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### Re: Formal charge purpose

Calculating the formal charge is important because if it adds up to 0, then the Lewis structure is the most stable.

victoria1l
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### Re: Formal charge purpose

Instead of calculating the formal charge, could one simply make sure that all the atoms have the correct number of valence electrons ? or would this not work all the time?

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### Re: Formal charge purpose

victoria1l wrote:Instead of calculating the formal charge, could one simply make sure that all the atoms have the correct number of valence electrons ? or would this not work all the time?

I believe that method would not work all of the time because some elements violate the octet rule. For instance, phosphorous holds up to 10 electrons and sulfur holds up to 12 electrons. (There are more exceptions than those I just mentioned.)

victoria1l
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### Re: Formal charge purpose

Oh okay thank you !

victoria1l
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### Re: Formal charge purpose

Is calculating the formal charge on a test necessary? will it be worth points?

Surya Palavali 1D
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### Re: Formal charge purpose

Because you always want the lowest formal charge possible in order to have the most stable Lewis Structure. I heard from my TA that it is possible you will have to calculate formal charges for points on either Test 3 or the final.

FizaBaloch1J
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### Re: Formal charge purpose

This is because you are trying to find the most stable lewis structure for a molecular formula, and to do this you need to determine the formal charges of each resonance.

Amir Akhavan 1E
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### Re: Formal charge purpose

The formal charge allows you to find the most stable form of the structure possible.

Garrett Dahn 1I
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### Re: Formal charge purpose

If having a formal charge of 0 means that an atom is most stable, then why do atoms like chlorine tend to have a negative charge when isolated (ie Cl-)?

I'm not entirely sure I'm correct here, but I think the reason we usually write Cl as Cl- doesn't have to do with formal charge so much as the fact that Chlorine has seven valence electrons and therefore needs an additional electron to achieve a stable octet. Pure Chlorine with seven valence electrons (simply Cl) doesn't exist in nature because it is unstable. Instead, Chlorine is either bonded with another element (NaCl), itself (Cl2) or it exists as an anion (Cl-). It's the same reason Na is often denoted instead as Na+, since sodium exists in the world not as the unstable Na, but the cation Na+ or in a bonded molecule. It all has to do with ensuring that the version of Chlorine or Sodium we are dealing with is stable.

AlyssaRivera
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### Re: Formal charge purpose

As Professor Lavelle has explained, you want to have the lewis structure in the most stable form. It's important to know what each individual elements charge is because it determines where the element should be placed in the structure.

victoria1l
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### Re: Formal charge purpose

okay thanks!

Enzo_1I
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### Re: Formal charge purpose

For a molecules lewis structure, it is best to find the most stable version. This is determined by finding the lowest energy of the molecule, which is just making the Formal charge equal to zero.

Miya Lopez 1I
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### Re: Formal charge purpose

If you had a molecule with three different lewis structures (resonance) and they had formal charges each with multiple zeros, would you pick the lewis structure with the most zeros/lowest formal charge to be the most stable lewis structure of that molecule?

Emilee Hosking 1D
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### Re: Formal charge purpose

I believe that if there are multiple lewis structures that have an overall charge of 0, then it would just be a resonance right?

Elena Maneffa 1E
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### Re: Formal charge purpose

Because of resonance, you can create various different structures of the same compound. But the version with the lowest formal charge is the most suitable. For this reason, we calculate formal charge.

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### Re: Formal charge purpose

I agree with the responses, the goal is to get the formal charge to a minimum amount or 0. This is when the structure is most stable.

Kelly Zhang 1L
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### Re: Formal charge purpose

why is the element most stable when its formal charge is 0?

Yukta Italia 3I
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### Re: Formal charge purpose

kellyzhang1210 wrote:why is the element most stable when its formal charge is 0?

When the formal charge of an element is 0, it's in the neutral state, which means that the amount of electrons is kind of "balanced" so that's why there is less instability.

Selina Bellin 2B
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### Re: Formal charge purpose

to determine the most stable formation

George Ghaly 2L
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### Re: Formal charge purpose

Formal charge has to be considered when drawing lewis structures as it will help you figure out if there is a double bond or not while trying to figure out the most stable form of the compound.

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### Re: Formal charge purpose

Calculating formal charges allows us to draw the most stable structure. For example, it will tell us if we should consider double bonds within the molecules to create more stability.

abbydouglas1K
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### Re: Formal charge purpose

How do we know when it is necessary to calculate the formal charge?

g orloff 1J
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### Re: Formal charge purpose

formal charge allows us to determine which structure is the most stable when we draw it based on the available resonance structures.

Aidan Ryan 1B
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### Re: Formal charge purpose

abbydouglas3J
The formal charge is to determine which lewis structure is the most accurate. Whichever has the closest value to 0 is what you use.

Sophia Fox 4B
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### Re: Formal charge purpose

What does a non-zero formal charge mean, besides that the molecule isn't in its most stable state? Do the numbers actually mean anything?

Lopez_Melissa-Dis4E
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### Re: Formal charge purpose

Moris 1H wrote:Why us calculating formal charge important for every Lewis Structure?

Calculating the formal charge is important because when FC=0 that is when your structure is the most stable. That way you can verify that your structure is correct in terms of your placement of electrons.

John Liang 2I
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### Re: Formal charge purpose

The formal charge is important to calculate in order to find out which lewis dot structure is most prevalent in nature, and therefore the most accurate.

abby hyman
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### Re: Formal charge purpose

Formal charge indicates the gain or loss of electrons while forming covalent bonds. Used to find which is the most stable

Shail Avasthi 2C
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### Re: Formal charge purpose

Formal charges also allow you to compare different possible lewis structures for the same molecule. For example, if the oxygen atoms in one lewis structure have positive formal charges and negative formal charges in another, the second lewis structure is probably preferable (assuming that other factors are taken into account) since oxygen is more electronegative than, say, carbon or nitrogen, and would rather have a negative formal charge than the aforementioned elements.

chrischyu4a
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### Re: Formal charge purpose

A formal charge of 0 indicates that the molecule is at its most stable structure.

ashwathinair
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### Re: Formal charge purpose

Compounds naturally want to be at their most stable form. By using formal charges and equalling them to 0, we are better able to find what is ACTUALLY the most stable structure of the compound so that we know what the structure of the compound actually is in nature.

alex_4l
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### Re: Formal charge purpose

On a test, will it specify that we need to calculate the formal charge or should we do it either way just to be sure?

Tahlia Mullins
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### Re: Formal charge purpose

Especially when dealing with resonance, finding the formal charge of each lewis structure is essential to determining the most stable structure, with a formal charge of 0 or as close to 0 as possible.