Formal Charge


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405289292
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Joined: Thu Oct 03, 2019 12:16 am

Formal Charge

Postby 405289292 » Mon Nov 04, 2019 3:56 pm

Does formal charge have to be zero, or are we trying to get as many elements to a formal charge of zero as possible?

Brian Tangsombatvisit 1C
Posts: 78
Joined: Sat Aug 17, 2019 12:15 am

Re: Formal Charge

Postby Brian Tangsombatvisit 1C » Mon Nov 04, 2019 4:37 pm

To determine the most stable Lewis structure, you would see which one has the most formal charges that are closest to 0. Molecules that have a net positive or net negative charge will inevitably have one or two elements that do not have a formal charge of 0, since a molecule's formal charges are supposed to add up to the overall molecule's charge. Make sure that the more electronegative atom has the negative formal charge, if there are any.

For neutral molecules, however, you should expect that all of its elements have a formal charge of 0.

Alexis Webb 2B
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Joined: Thu Jul 11, 2019 12:15 am

Re: Formal Charge

Postby Alexis Webb 2B » Mon Nov 04, 2019 4:37 pm

The lowest energy lewis structure would typically be the one where most of the elements have a formal charge of zero. If the molecule as a whole has a charge though, the formal charges of the elements should add up to that charge.

Abby Soriano 1J
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Joined: Sat Aug 24, 2019 12:16 am

Re: Formal Charge

Postby Abby Soriano 1J » Mon Nov 04, 2019 4:54 pm

Sometimes formal charges are impossible to get to 0 (for instance in compounds that have a charge on them, such as BrO3-) during which you need to draw a Lewis structure that has the lowest amount of charges and the lowest overall charges on each atom.

Aprice_1J
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Joined: Wed Sep 18, 2019 12:16 am

Re: Formal Charge

Postby Aprice_1J » Sat Nov 09, 2019 11:30 am

The goal is to have the lowest formal charge for all of the atoms in the structure. Some rules to follow are that the charges of the atoms (if they have one) have to add up to the charge of the overall compound and if you have a negative charge it is better to put that on the more electronegative atom and if it is a positive charge you will put it on the least electronegative.

Nare Nazaryan 1F
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Joined: Fri Aug 09, 2019 12:17 am

Re: Formal Charge

Postby Nare Nazaryan 1F » Sat Nov 09, 2019 9:13 pm

If the compound is neutral, you would need all the formal charges to be zero. However, if it has a net charge then one or more atoms might have a negative or positive charge. You want the most electronegative atoms to have a negative charge (oxygen for example), and typically the central atom needs to have a charge of zero to be stable. Usually we want to get as many atoms to zero as possible.

Pablo 1K
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Joined: Sat Feb 02, 2019 12:15 am

Re: Formal Charge

Postby Pablo 1K » Sat Nov 09, 2019 9:49 pm

You always want to meet the net charge if an ion has a 2+ then you want to make sure some atom(s) are charged to meet that 2+. If there is no net charge then yes it will always have to be 0.

Emil Velasco 1H
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Joined: Wed Nov 21, 2018 12:19 am

Re: Formal Charge

Postby Emil Velasco 1H » Sat Nov 09, 2019 10:17 pm

You try to make the formal charge 0 where possible as long as the octet rule is satisfied. If not, you aim for the lowest energy structure possible that satisfies the octet rule, which involves having the lowest number of formal charges, especially with the central atom.

TimVintsDis4L
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Joined: Sat Aug 17, 2019 12:17 am

Re: Formal Charge

Postby TimVintsDis4L » Sat Nov 09, 2019 10:45 pm

A formal charge of 0 simply states that a Lewis Structure is at its lowest energy level. Some structures may not have a formal charge of 0, but the goal is to draw a structure so that it is at its lowest formal charge/ more stable.

Abigail_Hagen2G
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Joined: Fri Aug 09, 2019 12:17 am

Re: Formal Charge

Postby Abigail_Hagen2G » Sun Nov 10, 2019 8:14 pm

If the compound has no charge, then the formal charge should be zero.


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