Formal Charge and the Octet Rule


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josephyim1L
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Joined: Fri Sep 28, 2018 12:15 am

Formal Charge and the Octet Rule

Postby josephyim1L » Wed Oct 31, 2018 5:10 pm

In determining the preferred Lewis Structure diagram for a given molecule, what is more important to consider: achieving and maintaining an octet or having a formal charge of 0?

Will there ever be a case when a formal charge of no 0 (1,2,-1,-2) will be preferred to having an octet?

Clarissa Cabil 1I
Posts: 66
Joined: Fri Sep 28, 2018 12:19 am

Re: Formal Charge and the Octet Rule

Postby Clarissa Cabil 1I » Wed Oct 31, 2018 5:18 pm

When determining Lewis structures, there are exceptions to the octet rule. So, not all atoms will follow the octet rule due to expanded valence shells. In lecture, however, Dr. Lavelle mentioned how atoms are the most stable when they have a formal charge of 0.

Theodore_Herring_1A
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Joined: Fri Sep 28, 2018 12:29 am

Re: Formal Charge and the Octet Rule

Postby Theodore_Herring_1A » Thu Nov 01, 2018 2:31 pm

When determining Lewis structures, start off by following the octet rule, and then determine any alternate depictions. Keep in mind that not all atoms require 8 valence electrons. Then compare between the different Lewis structures for the lowest FC of each atom/overall FC of the molecule or compound.

sophiebillings1E
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Joined: Fri Sep 28, 2018 12:27 am

Re: Formal Charge and the Octet Rule

Postby sophiebillings1E » Thu Nov 01, 2018 2:49 pm

Remember the exceptions to expanding the octet rule begin in period three because that period has the d block only then can the octet rule be altered. However, elements like B and Al can be a part of Lewis acid-base reactions and may only have 6 valence electrons.

Max Kwon 1J
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Re: Formal Charge and the Octet Rule

Postby Max Kwon 1J » Fri Nov 02, 2018 10:09 am

The octet rule can be broken for the 3 sub shells as they have s,p, and d. That means their lewis structures can have more than 4 bonds or more than 8 electrons, and Lavelle showed some examples during lecture.

Jaedyn_Birchmier3F
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Joined: Fri Sep 28, 2018 12:26 am

Re: Formal Charge and the Octet Rule

Postby Jaedyn_Birchmier3F » Sat Nov 03, 2018 12:22 pm

Not all Lewis structures need to have a formal charge of 0, it depends on the molecule. For example ammonium has a formal charge of +1 because the molecule itself is NH4+. Therefore, don't always a assume a formal charge of 0 is necessary.

ThomascnguyenDis1J
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Joined: Fri Sep 28, 2018 12:16 am

Re: Formal Charge and the Octet Rule

Postby ThomascnguyenDis1J » Sun Nov 11, 2018 3:09 pm

The formal charge must always equal to the charge of the entire molecule.


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