Easy way to remember octet exceptions

[Katherine Brenner 3H]

Hello

Is there any easy way to remember the octet exceptions?

[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).

[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.

[Jorge Ramirez_4H]

There are only 3 exceptions right?

[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.