Reasoning for Octet Exception

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Ashley Kao 1H
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Joined: Thu Jul 25, 2019 12:16 am

Reasoning for Octet Exception

Postby Ashley Kao 1H » Sat Nov 09, 2019 11:45 pm

I understand that Si, P, S, and Cl can all have expanded octets, but what properties allows these specific elements to do so?

Cassidy Kohlenberger 3D
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Joined: Wed Sep 18, 2019 12:19 am

Re: Reasoning for Octet Exception

Postby Cassidy Kohlenberger 3D » Sun Nov 10, 2019 12:01 am

As all these elements are located in period 3, they can have expanded octets through using their energetically accessible, low-lying d sub-shell for bonding. This is why period 2 elements cannot have an expanded octet, as they don't have access to the d sub-shell.

Aliya Jain 2B
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Joined: Wed Sep 11, 2019 12:16 am

Re: Reasoning for Octet Exception

Postby Aliya Jain 2B » Sun Nov 10, 2019 5:29 pm

Also, expanded octets can occur in all elements starting period 3 and below!

sbeall_1C
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Re: Reasoning for Octet Exception

Postby sbeall_1C » Sun Nov 10, 2019 5:46 pm

Yes, it is because of the presence of the d-orbital in the elements staring in period 3! This d-orbital can accommodate the extra electrons! If you look at the formal charge for the elements you mentioned (Si, P, S, and Cl) you can see that having more than the octet minimizes the formal charge and brings it closer to the stable 0, which helps you recognize when an expanded octet would be beneficial.

Ashley Kumar 3F
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Joined: Sat Sep 07, 2019 12:18 am

Re: Reasoning for Octet Exception

Postby Ashley Kumar 3F » Sun Nov 10, 2019 5:48 pm

The d orbital can account for the extra electrons which is why elements from period 3 and beyond can have an expanded octet

Tyler Angtuaco 1G
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Re: Reasoning for Octet Exception

Postby Tyler Angtuaco 1G » Sun Nov 10, 2019 5:50 pm

Any element in the third period or below can have an expanded octet because the d-shell exists, and is filled after the ns subshell.

Kaylee Clarke 1G
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Joined: Fri Aug 30, 2019 12:15 am

Re: Reasoning for Octet Exception

Postby Kaylee Clarke 1G » Sun Nov 10, 2019 6:18 pm

expanded octets occur in period 3 and below but they are most common in phosphorus, sulfur, and chlorine.

Liliana Aguas 3G
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Joined: Wed Sep 18, 2019 12:20 am

Re: Reasoning for Octet Exception

Postby Liliana Aguas 3G » Sun Nov 10, 2019 11:34 pm

Only elements from period 3 and beyond can have expanded octets as they can fill up the empty d orbitals that follow higher in energy.

Caitlin Ciardelli 3E
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Joined: Wed Sep 18, 2019 12:19 am

Re: Reasoning for Octet Exception

Postby Caitlin Ciardelli 3E » Fri Nov 15, 2019 12:51 am

Rows three and beyond can have an expanded octet (hold more than 8 electrons) because they have access to the s, p AND d orbitals. Having access the the d orbital allows ten electrons to be used in addition to the octet. Rows 2 and above cannot have an expanded octet because they only utilize s and p. Hope this helps!

Megan_1F
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Joined: Thu Jul 25, 2019 12:16 am

Re: Reasoning for Octet Exception

Postby Megan_1F » Fri Nov 15, 2019 9:43 pm

Row 3 and beyond can have an expanded octet because it's in the 3rd energy level - S, P, and D blocks.

Mai V 4L
Posts: 55
Joined: Fri Sep 28, 2018 12:23 am

Re: Reasoning for Octet Exception

Postby Mai V 4L » Sun Dec 08, 2019 9:14 am

Does anyone have a video they think is a good referencce for this topic?

MKearney_4G
Posts: 50
Joined: Fri Aug 30, 2019 12:18 am

Re: Reasoning for Octet Exception

Postby MKearney_4G » Sun Dec 08, 2019 4:35 pm

I know it's probably late but this video does a good job explaining it : https://youtu.be/96L6_IwyHRM


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