When to use Expanded Octet?

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RRahimtoola1I
Posts: 102
Joined: Fri Aug 09, 2019 12:15 am

When to use Expanded Octet?

Postby RRahimtoola1I » Tue Nov 05, 2019 11:28 pm

Are you supposed to use an expanded octet if you can make a Lewis Structure without it? For example, in ClO would I give Cl 9 electrons by making a double bond or leave it with 7 with a single bond even though the single bond gives Cl a -1 formal charge?

Justin Sarquiz 2F
Posts: 106
Joined: Fri Aug 30, 2019 12:15 am

Re: When to use Expanded Octet?

Postby Justin Sarquiz 2F » Wed Nov 06, 2019 9:10 am

We should use the expanded octet in order to find the lowest energy Lewis structure. This means that we want the Lewis structure with the lowest formal charges. Therefore, it is crucial to solve for the formal charges whenever drawing Lewis structures because it shows whether the Lewis structure drawn is the most likely.

Rory Simpson 2F
Posts: 106
Joined: Fri Aug 09, 2019 12:17 am

Re: When to use Expanded Octet?

Postby Rory Simpson 2F » Wed Nov 06, 2019 11:09 am

If you want to find the most stable Lewis structure, you would want to minimize formal charge and then use expanded octets if possible. Remember that expanded octets only apply for atoms in the 3rd period and after because they have d-orbitals available in their valence shell.


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