Octet Exceptions

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mbaker4E
Posts: 69
Joined: Fri Sep 28, 2018 12:26 am

Octet Exceptions

Postby mbaker4E » Tue Nov 06, 2018 12:19 am

How do you know if an element is an exception to the octet rule?

Fanny Lee 2K
Posts: 73
Joined: Fri Sep 28, 2018 12:29 am

Re: Octet Exceptions

Postby Fanny Lee 2K » Tue Nov 06, 2018 12:26 am

Elements in period 3 or lower on the periodic table can have an expanded octet. Elements H, He, Li, Be, and group 13 can have incomplete octets. Elements in the 2p orbital can only have an octet.

AlyssaBei_1F
Posts: 99
Joined: Fri Sep 28, 2018 12:17 am

Re: Octet Exceptions

Postby AlyssaBei_1F » Tue Nov 06, 2018 12:43 am

H, He, Li, and Be do not obtain a full octet. Elements in period 3 or below can have an expanded octet, including S, P, and Cl.

RachaelKoh3A
Posts: 33
Joined: Fri Sep 28, 2018 12:25 am

Re: Octet Exceptions

Postby RachaelKoh3A » Tue Nov 06, 2018 11:38 am

To add on, the elements in period 3 and below can exceed an octet because it has d orbitals. These d orbitals are energetically accessible and can hence have an expanded octet.
Elements that are in the second period cannot exceed 8 electrons because there are only 2s and 2p sub-shells that can hold a maximum of 8 valence electrons at the second principal quantum level.

Ava Kjos 1D
Posts: 65
Joined: Fri Sep 28, 2018 12:19 am

Re: Octet Exceptions

Postby Ava Kjos 1D » Tue Nov 06, 2018 11:54 am

The only elements that the octet always applies to is B, C, N, O, F. The max number of electrons they can have is 8 because there is no 2d orbital, meaning once they fill up the 2s and 2p orbitals there's no room left for any additional bonds. Once you reach period 3, the 3d orbital can be utilized to create additional bonds and exceed 8 electrons.


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