Easy way to remember octet exceptions

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Katherine Brenner 3H
Posts: 73
Joined: Wed Sep 18, 2019 12:18 am

Easy way to remember octet exceptions

Postby Katherine Brenner 3H » Tue Nov 05, 2019 10:23 pm

Hello

Is there any easy way to remember the octet exceptions?

Sebastian Lee 1L
Posts: 157
Joined: Fri Aug 09, 2019 12:15 am
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Re: Easy way to remember octet exceptions

Postby Sebastian Lee 1L » Tue Nov 05, 2019 10:25 pm

Basically, if the element is in the 3rd row of the periodic table or beyond, it can have an expanded octet. For incomplete octets, it's H, He, Li, Be, B and the rest of the group 13 elements (like Al).

chrischyu4a
Posts: 52
Joined: Thu Jul 25, 2019 12:16 am

Re: Easy way to remember octet exceptions

Postby chrischyu4a » Thu Nov 07, 2019 1:33 pm

Also it is helpful to check the formal charge on the central ion as expanded octets usually contribute to decreasing the formal charge to 0.

Jorge Ramirez_4H
Posts: 54
Joined: Wed Nov 21, 2018 12:19 am

Re: Easy way to remember octet exceptions

Postby Jorge Ramirez_4H » Thu Nov 07, 2019 2:26 pm

There are only 3 exceptions right?

Kayla Maldonado 1C
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Re: Easy way to remember octet exceptions

Postby Kayla Maldonado 1C » Thu Nov 07, 2019 3:43 pm

Any atom with a d orbital has the octet exception. Atoms in row one and two only have the p and s orbitals and thus eight valence electrons, the p orbital has six and the s orbital two. With the addition of a d orbital, atoms are able to accommodate more than eight valence electrons by putting some in the d orbital which can accept ten electrons. Since the d orbital start in the n=3 row then any atom from n=3 and below can have an expanded octet.


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