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Easy way to remember octet exceptions

Posted: Tue Nov 05, 2019 10:23 pm
by Katherine Brenner 3H
Hello

Is there any easy way to remember the octet exceptions?

Re: Easy way to remember octet exceptions

Posted: Tue Nov 05, 2019 10:25 pm
by Sebastian Lee 1L
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).

Re: Easy way to remember octet exceptions

Posted: Thu Nov 07, 2019 1:33 pm
by chrischyu4a
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.

Re: Easy way to remember octet exceptions

Posted: Thu Nov 07, 2019 2:26 pm
by Jorge Ramirez_4H
There are only 3 exceptions right?

Re: Easy way to remember octet exceptions

Posted: Thu Nov 07, 2019 3:43 pm
by Kayla Maldonado 1C
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.