Expanded Octet Rules

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Justin Bui 2L
Posts: 51
Joined: Fri Sep 29, 2017 7:06 am

Expanded Octet Rules

Postby Justin Bui 2L » Sun Dec 03, 2017 11:35 pm

At what point in the periodic table do expanded octets become a possibility and why?

Gurshaan Nagra 2F
Posts: 49
Joined: Thu Jul 27, 2017 3:01 am

Re: Expanded Octet Rules

Postby Gurshaan Nagra 2F » Sun Dec 03, 2017 11:40 pm

It begins with the non-metals in the third period or below, they are able to do this because they have empty d subshells that can house the extra electrons.

AtreyiMitra2L
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Re: Expanded Octet Rules

Postby AtreyiMitra2L » Sun Dec 03, 2017 11:41 pm

Expanded octets become a possibility at 3p. It becomes a possibility bc 3d is right above it. This sub shell can hold more electrons which is why atoms like P, S, and Cl can hold an expanded octet.

Harmonie Ahuna-1C
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Joined: Fri Apr 06, 2018 11:01 am

Re: Expanded Octet Rules

Postby Harmonie Ahuna-1C » Sat May 19, 2018 3:00 pm

Gurshaan Nagra 2F wrote:It begins with the non-metals in the third period or below, they are able to do this because they have empty d subshells that can house the extra electrons.

Based off of what we learned with quantum numbers and electron shells & subshells, I always thought 3p came before 3d so how is this possible?

Cindy Nguyen 1L
Posts: 48
Joined: Fri Apr 06, 2018 11:04 am

Re: Expanded Octet Rules

Postby Cindy Nguyen 1L » Sun May 20, 2018 12:43 am

For the third row of the periodic table, we don't put any d-orbital electrons in their ground state configurations as they don't have any in the d orbital. However, since their energy level is 3 (n=3), they are able to have more electrons. They have a whole new shell rather than be just n=2, so there's space to house more electrons. As mentioned above, the quantum numbers show how this is possible.

Madeleine Farrington 1B
Posts: 32
Joined: Fri Apr 06, 2018 11:02 am

Re: Expanded Octet Rules

Postby Madeleine Farrington 1B » Sun May 20, 2018 3:06 pm

When given a molecule with an atom in it with the possibility for an expanded octet and asked to draw the Lewis structure, is there any intuitive trick to determine if an expanded octet is actually needed other than guess and check? For example, question 3.63 part a asks you to draw the Lewis Structure of the molecule SF6, and the only way that I figured out that I would need to draw it with more than 8 electrons around S was through attempting to draw it with a regular octet around each atom only to find that the valence electrons did not add up to 48 as they should for this molecule.

Chiara Berruto 1K
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Joined: Fri Apr 06, 2018 11:01 am

Re: Expanded Octet Rules

Postby Chiara Berruto 1K » Sun May 20, 2018 9:17 pm

Cindy Nguyen 1L wrote:For the third row of the periodic table, we don't put any d-orbital electrons in their ground state configurations as they don't have any in the d orbital. However, since their energy level is 3 (n=3), they are able to have more electrons. They have a whole new shell rather than be just n=2, so there's space to house more electrons. As mentioned above, the quantum numbers show how this is possible.


Since these atoms are able to house more electrons due to the availability of the 3d shell is it safe to assume that they can only hold extra electrons up to the point where the 3d orbital becomes full?

Cindy Nguyen 1L
Posts: 48
Joined: Fri Apr 06, 2018 11:04 am

Re: Expanded Octet Rules

Postby Cindy Nguyen 1L » Mon May 21, 2018 12:32 am

Chiara Berruto 1K wrote:
Cindy Nguyen 1L wrote:For the third row of the periodic table, we don't put any d-orbital electrons in their ground state configurations as they don't have any in the d orbital. However, since their energy level is 3 (n=3), they are able to have more electrons. They have a whole new shell rather than be just n=2, so there's space to house more electrons. As mentioned above, the quantum numbers show how this is possible.


Since these atoms are able to house more electrons due to the availability of the 3d shell is it safe to assume that they can only hold extra electrons up to the point where the 3d orbital becomes full?

Technically yes. Although when we draw Lewis structures for them, it's not like they need the whole d-orbital to be filled. We've seen examples of compounds that use their expanded octets but there are only a few extra electrons (not 10).


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