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### Octet rule vs. Formal charge

Posted: Tue Nov 06, 2018 12:20 am
What is more important when drawing a Lewis Diagram of the lowest energy - the octet rule or formal charge?

### Re: Octet rule vs. Formal charge

Posted: Tue Nov 06, 2018 12:44 am
All elements must have an octet, but you look at formal charge to find the most stable Lewis structure.

### Re: Octet rule vs. Formal charge

Posted: Tue Nov 06, 2018 1:58 pm
Not all elements can hold more than an octet, but when you're dealing with the ones that can like S and P, if the formal charge of the elements would be closer to 0 after breaking the octet rule, then you should break the octet.

### Re: Octet rule vs. Formal charge

Posted: Tue Nov 06, 2018 2:30 pm
From my knowledge and TA comments, I have the impression that the octet is the first thing to satisfy when drawing a lewis structure. Then once each octet is full, you can rearrange the electrons to create the closest formal charge to zero.

### Re: Octet rule vs. Formal charge

Posted: Tue Nov 06, 2018 6:58 pm
Row three elements and below can hold more than an octet is because they have a d-orbital shell to expand on.

### Re: Octet rule vs. Formal charge

Posted: Tue Nov 06, 2018 8:14 pm
For elements with expanded octets, is there no maximum number of bonds it's allowed to have? Is it just the number of bonds that will satisfy the lowest formal charge rule?

### Re: Octet rule vs. Formal charge

Posted: Tue Nov 06, 2018 9:20 pm
Kelly Zhang 1L wrote:For elements with expanded octets, is there no maximum number of bonds it's allowed to have? Is it just the number of bonds that will satisfy the lowest formal charge rule?

Yes as long as the element doesn't exceed the amount of valence electrons it has (which should not be a problem because formal charge accounts for that)

### Re: Octet rule vs. Formal charge

Posted: Tue Nov 06, 2018 10:41 pm
Octet is preferred, formal charge is used to choose between structures that already fulfill the octet.