Octet Exceptions

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aaronharouni
Posts: 72
Joined: Fri Sep 28, 2018 12:15 am

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
Posts: 63
Joined: Fri Sep 28, 2018 12:16 am

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.

Danielle_Gallandt3I
Posts: 70
Joined: Fri Sep 28, 2018 12:24 am

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
Posts: 35
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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