Why does PCl5 break the Octet Rule?


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AJ Manzano 3K
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Joined: Thu Sep 27, 2018 11:25 pm

Why does PCl5 break the Octet Rule?

Postby AJ Manzano 3K » Sun Nov 04, 2018 2:49 pm

When could the octet rule be broken? In Wednesday's lecture, Dr. Lavelle drew the Lewis structure for phosphorus pentachloride (PCl5), and 5 chlorine atoms were attached to one phosphorus. Why can Phosphorus have 5 bonds instead of 4?

Timothy_Yueh_4D
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Joined: Thu Sep 27, 2018 11:28 pm

Re: Why does PCl5 break the Octet Rule?

Postby Timothy_Yueh_4D » Sun Nov 04, 2018 2:55 pm

Phosphorus can form an expanded octet with 5 bonds due to the fact that it exists in the 3rd period, giving it access to the d-orbitals associated in the 3rd shell (3d).

Milena Aragon 2B
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Joined: Thu Sep 27, 2018 11:19 pm

Re: Why does PCl5 break the Octet Rule?

Postby Milena Aragon 2B » Sun Nov 04, 2018 3:03 pm

Molecules in the 3rd period and above can access the d-orbitals (which can accommodate 10 more electrons since there are 5 d-orbitals) since their angular momentums are l=2 or more.

Rami_Z_AbuQubo_2K
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Joined: Thu Jun 07, 2018 2:00 am

Re: Why does PCl5 break the Octet Rule?

Postby Rami_Z_AbuQubo_2K » Sun Nov 04, 2018 7:03 pm

Since P is the least electro-negative, it will be the central element. Considering that anything from group 3 to 7 in the p block has an expanded octet, which includes P, that means that it will break the octet rule.

ran2000
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Joined: Thu Sep 27, 2018 11:15 pm

Re: Why does PCl5 break the Octet Rule?

Postby ran2000 » Sun Nov 04, 2018 7:28 pm

This is because phosphorous can utilize the d orbitals and, thus, has an expanded octet.

Anand Narayan 1G
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Joined: Thu Sep 27, 2018 11:15 pm

Re: Why does PCl5 break the Octet Rule?

Postby Anand Narayan 1G » Mon Nov 05, 2018 3:37 pm

This is because Phosphorous is in the 3rd energy level, which means it can access the d-orbitals in order to have an expanded octet and form more than 4 bonds.

Aleeque Marselian 1A
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Joined: Thu Sep 27, 2018 11:24 pm

Re: Why does PCl5 break the Octet Rule?

Postby Aleeque Marselian 1A » Mon Nov 05, 2018 8:42 pm

Phosphorous, Chlorine, and Sulfur can accommodate more than eight electrons and therefore break the octet rule because they contain a 3d orbital.

Yixiao Hu 3C
Posts: 45
Joined: Thu Sep 27, 2018 11:19 pm

Re: Why does PCl5 break the Octet Rule?

Postby Yixiao Hu 3C » Mon Nov 05, 2018 9:51 pm

because it is on the period 3, so it order to have the lowest energy structure, the pcl5 can break the octet rule.

Jayde Felix 4H
Posts: 59
Joined: Thu Sep 27, 2018 11:28 pm

Re: Why does PCl5 break the Octet Rule?

Postby Jayde Felix 4H » Mon Nov 05, 2018 10:21 pm

P is in the third row and can have an expanded octet. Any element in the third row or below can have an expanded octet.


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