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octet exceptions

Posted: Sun Nov 03, 2019 11:49 pm
by Aashka Popat 1A
What elements do the exceptions to the octet rule apply to and why is this able to happen?

Re: octet exceptions

Posted: Mon Nov 04, 2019 9:37 am
by Robin Cadd 1D
The only elements that hold stead-fast to the octet rule are C, N, O, F, and Ne. Hydrogen and helium will always have less than an octet (precisely, 2 electrons) because of the number of electrons their orbitals are able to accommodate. As a general rule, elements in the p-block with shell n=3 or greater will be able to accommodate more than 8 electrons because of their unfilled d-subshell. Hope this helps.

Re: octet exceptions

Posted: Mon Nov 04, 2019 9:47 am
by Wendy Perez 1E
Boron is also an exception to the octet rule as it can be content with 6 valence electrons, instead of an octet.

Re: octet exceptions

Posted: Mon Nov 04, 2019 11:55 am
by Sion Hwang 4D
Elements that are period 3 and beyond in the periodic table have access to the d-orbitals, which can fill up to 10 extra valence electrons. One example of this is SF6, where sulfur has 6 bonds to each fluorine atom and thus has 12 valence electrons.

Some elements, such as B and Al can have incomplete octets because they can be relatively stable with only 6 valence electrons.

Hydrogen and beryllium are also exceptions to the octet, as they have too few electrons to complete an octet.

Re: octet exceptions

Posted: Tue Nov 05, 2019 9:38 am
by Sharon Rodriguez 3H
Sion Hwang 4D wrote:Elements that are period 3 and beyond in the periodic table have access to the d-orbitals, which can fill up to 10 extra valence electrons. One example of this is SF6, where sulfur has 6 bonds to each fluorine atom and thus has 12 valence electrons.

Some elements, such as B and Al can have incomplete octets because they can be relatively stable with only 6 valence electrons.

Hydrogen and beryllium are also exceptions to the octet, as they have too few electrons to complete an octet.


Why are B and Al realtively stable with only 6 while others require an octect?

Re: octet exceptions

Posted: Tue Nov 05, 2019 10:39 am
by Maddie
I would also note to be mindful of this exception especially when writing the electron configuration for Cu and Cr

Re: octet exceptions

Posted: Fri Nov 08, 2019 10:09 pm
by MeeraBhagat
Elements in the third energy level and higher can have more than an octet. This is because they have empty d orbitals available to hold the extra electrons.

Re: octet exceptions

Posted: Sat Nov 09, 2019 10:16 pm
by Emil Velasco 1H
Usually any element under the 3rd period may have an expanded octet due to having the whole of the d-block possible in their electron configuration

Re: octet exceptions

Posted: Sun Nov 10, 2019 12:47 pm
by AniP_2D
C, N, O, F, and Ne are the main elements that must follow the octet rule. There are elements like hydrogen that only need two and those like boron that need 6. Also any element past phosphorus can hold more than 8 electrons.

Re: octet exceptions

Posted: Sun Nov 10, 2019 1:47 pm
by Rohan Kubba Dis 4B
There are many octet exceptions. First, H only needs one electron to complete its shell, and this extends to He and a couple of other elements. Next, we have expanded octets which can be any element in the third period which includes P, S, and Cl. Moreover, then we have radicals and biradicals. Although this is a very rudimentary definition of radicals, the basic ideas is that you have an odd number of electrons or you have two single electrons where a pair should be. In any case, if you have an odd number of electrons, completing the octet may not be achievable. In essence, you do the most you can and give any (leftover) electrons to the most electronegative element.

Re: octet exceptions

Posted: Sun Nov 10, 2019 2:00 pm
by SarahCoufal_1k
Basically most elements in period 3 and beyond. This is because there is now the D sub shell that can be filled. In addition Boron can be satisfied with either 8 or 6 electrons.

Re: octet exceptions

Posted: Sun Nov 10, 2019 2:08 pm
by Merin Padayatty 3G
All elements in period 3 and after can have an expanded octet.