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Octet exceptions and Formal charges.

Posted: Thu May 10, 2018 11:26 am
by Kaleb Tesfaye 1I
Since elements in the third row or below can have octet exceptions, is it mandatory to use the formal charge to determine what kind of lewis structure they have and whether or not they have resonances?

Re: Octet exceptions and Formal charges.

Posted: Thu May 10, 2018 12:32 pm
by kendallbottrell
A lot of time you can use the idea of symmetry when doing bonding questions, but just to make sure you're actually correct, it is important to do the formal charge calculations. From there you would be able to tell if the structures have resonances easier too.

Re: Octet exceptions and Formal charges.

Posted: Fri May 11, 2018 1:19 am
by Endri Dis 1J
When looking at octet exceptions there are two cases where the octet can be incomplete or expanded but I don't understand the characteristics of each one?

Re: Octet exceptions and Formal charges.

Posted: Fri May 11, 2018 1:23 am
by Endri Dis 1J
Oh and also for the formal charge calculation is there an easier way to calculate the charge?

Re: Octet exceptions and Formal charges.

Posted: Sun May 13, 2018 4:29 pm
by Vienna Cimetta 1L
Yeah you should check to make sure you find the structure with a formal change closest to zero, because they said last class that will be the only correct answer. When they ask for a lewis diagram, they want the most stable one.

Re: Octet exceptions and Formal charges.

Posted: Tue May 22, 2018 1:42 pm
by Daniel Cho Section 1H
When it comes to Lewis Structures, it becomes very paramount to calculating the formal charges because the main requirements to get a finalized lewis structure is that the elements are fully satisfied with their octet rules excluding the central atom that is period 3 and below as well as the other exceptions, and to make the formal charge as low as possible.

Formal charges are there to make sure the structure you draw is as stable as possible.

I hope this helps. Please correct me if I am wrong in certain places.

Re: Octet exceptions and Formal charges.

Posted: Sat May 26, 2018 9:57 pm
by AlyssaRivera
Elements that do not follow the octet rule is one of the biggest reason why we use the formal charge equations. Because these elements do not follow the typical trends that others do, this formula provides an accurate charge to use when trying to make a stable, or the most stable form of a lewis structure possible. For these exceptions, we cannot simply look at the periodic table like others.