Octet Exceptions

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Octet Exceptions

Postby aaronharouni » Wed Nov 07, 2018 1:22 am

What is an easy way to remember all of the exceptions of octet?

Diego Gonzalez 3F
Posts: 32
Joined: Fri Sep 28, 2018 12:26 am

Re: Octet Exceptions

Postby Diego Gonzalez 3F » Wed Nov 07, 2018 6:04 am

everything in period 3 and below may have an expanded octet (bc their energy level allows D subshell to be filled)
Everything in group 13 is satisfied WITHOUT a full octet.

So I just remember period 3 and below expand
Group 13- satisfied with less

Max Hayama 4K
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Re: Octet Exceptions

Postby Max Hayama 4K » Wed Nov 07, 2018 11:16 am

When drawing your Lewis structures, make sure to accommodate an octet for any element in period 2, while any element in period 3 and above can have an expanded octet. This depends on the formal charge of the central atom and the surrounding atoms to ensure that the lowest energy state is achieved.

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Re: Octet Exceptions

Postby Danielle_Gallandt3I » Wed Nov 07, 2018 11:20 am

The elements you would typically see with an expanded octet are going to be in Period 3 or below and most likely in the p-block (right side of periodic table and mostly nonmetals) because they have an empty d-orbital.

Leslie Cheng 4B
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Joined: Fri Sep 28, 2018 12:29 am

Re: Octet Exceptions

Postby Leslie Cheng 4B » Wed Nov 07, 2018 12:35 pm

I just remember three octet exceptions:
1) expanded valence shells-any element in period 3 or above can accommodate more than an octet because its electrons can go into its d-orbitals
2) incomplete octets-elements in group 13 like Boron will have an odd number of electrons so they won't get an octet through covalent bonding
3) radicals-compounds with unpaired electrons, highly reactive and only exist for a short period of time

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