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Formal charge purpose

Posted: Sun May 13, 2018 5:05 pm
by Moris 1H
Why us calculating formal charge important for every Lewis Structure?

Re: Formal charge purpose

Posted: Sun May 13, 2018 5:22 pm
by Jonghwee Park 1K
I think it’s because of the formal charge adds up to 0, the Lewis structure is the most stable.

Re: Formal charge purpose

Posted: Sun May 13, 2018 5:57 pm
by Heung Ching Chia 1E
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.

Re: Formal charge purpose

Posted: Sun May 13, 2018 6:31 pm
by Moris 1H
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?

Re: Formal charge purpose

Posted: Sun May 13, 2018 6:47 pm
by salvadoralvizo1J
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-)?

Re: Formal charge purpose

Posted: Sun May 13, 2018 7:49 pm
by Amanda 1A
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

Re: Formal charge purpose

Posted: Sun May 13, 2018 8:18 pm
by Molly Oakes 1A
Making the formal charge as close to zero as possible determines the best Lewis structure.

Re: Formal charge purpose

Posted: Sun May 13, 2018 8:47 pm
by Caitlyn Ponce 1L
Formal charge can also be used to check if your Lewis Structure is correct for charged molecules.

Re: Formal charge purpose

Posted: Sun May 13, 2018 8:59 pm
by CarinaVargas1J
Calculating the formal charge is important because if it adds up to 0, then the Lewis structure is the most stable.

Re: Formal charge purpose

Posted: Sun May 13, 2018 9:13 pm
by victoria1l
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?

Re: Formal charge purpose

Posted: Sun May 13, 2018 9:34 pm
by Jada Larson 1F
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.)

Re: Formal charge purpose

Posted: Sun May 20, 2018 7:51 pm
by victoria1l
Oh okay thank you !

Re: Formal charge purpose

Posted: Sun May 20, 2018 7:53 pm
by victoria1l
Is calculating the formal charge on a test necessary? will it be worth points?

Re: Formal charge purpose

Posted: Sun May 20, 2018 8:35 pm
by Surya Palavali 1D
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.

Re: Formal charge purpose

Posted: Sun May 20, 2018 9:03 pm
by FizaBaloch1J
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.

Re: Formal charge purpose

Posted: Sun May 20, 2018 10:24 pm
by Amir Akhavan 1E
The formal charge allows you to find the most stable form of the structure possible.

Re: Formal charge purpose

Posted: Sun May 20, 2018 10:48 pm
by Garrett Dahn 1I
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.

Hope this can be helpful!

Re: Formal charge purpose

Posted: Sat May 26, 2018 9:52 pm
by AlyssaRivera
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.

Re: Formal charge purpose

Posted: Sun Jun 03, 2018 10:39 pm
by victoria1l
okay thanks!

Re: Formal charge purpose

Posted: Sun Jun 03, 2018 10:52 pm
by Enzo_1I
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.

Re: Formal charge purpose

Posted: Sun Jun 03, 2018 10:58 pm
by Miya Lopez 1I
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?

Re: Formal charge purpose

Posted: Tue Oct 30, 2018 7:52 pm
by Emilee Hosking 1D
I believe that if there are multiple lewis structures that have an overall charge of 0, then it would just be a resonance right?

Re: Formal charge purpose

Posted: Tue Oct 30, 2018 9:11 pm
by Elena Maneffa 1E
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.

Re: Formal charge purpose

Posted: Wed Oct 31, 2018 6:37 pm
by Madeera_Mian_3B
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.

Re: Formal charge purpose

Posted: Wed Oct 31, 2018 9:01 pm
by Kelly Zhang 1L
why is the element most stable when its formal charge is 0?

Re: Formal charge purpose

Posted: Thu Nov 01, 2018 1:03 pm
by Yukta Italia 3I
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.

Re: Formal charge purpose

Posted: Thu Nov 01, 2018 3:02 pm
by Selina Bellin 2B
to determine the most stable formation

Re: Formal charge purpose

Posted: Thu Nov 01, 2018 5:14 pm
by George Ghaly 2L
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.

Re: Formal charge purpose

Posted: Thu Nov 01, 2018 9:58 pm
by Madelyn Romberg 3L
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.

Re: Formal charge purpose

Posted: Thu Nov 01, 2018 10:17 pm
by abbydouglas1K
How do we know when it is necessary to calculate the formal charge?

Re: Formal charge purpose

Posted: Thu Nov 01, 2018 10:58 pm
by g orloff 1J
formal charge allows us to determine which structure is the most stable when we draw it based on the available resonance structures.

Re: Formal charge purpose

Posted: Thu Nov 01, 2018 11:08 pm
by Aidan Ryan 1B
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.

Re: Formal charge purpose

Posted: Fri Nov 02, 2018 10:37 am
by Sophia Fox 4B
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?

Re: Formal charge purpose

Posted: Fri Nov 02, 2018 11:06 am
by Lopez_Melissa-Dis4E
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.