Page 1 of 1

Why does PCl5 break the Octet Rule?

Posted: Sun Nov 04, 2018 2:49 pm
by AJ Manzano 3K
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?

Re: Why does PCl5 break the Octet Rule?

Posted: Sun Nov 04, 2018 2:55 pm
by Timothy_Yueh_4L
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).

Re: Why does PCl5 break the Octet Rule?

Posted: Sun Nov 04, 2018 3:03 pm
by Milena Aragon 2B
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.

Re: Why does PCl5 break the Octet Rule?

Posted: Sun Nov 04, 2018 7:03 pm
by Rami_Z_AbuQubo_2K
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.

Re: Why does PCl5 break the Octet Rule?

Posted: Sun Nov 04, 2018 7:28 pm
by ran2000
This is because phosphorous can utilize the d orbitals and, thus, has an expanded octet.

Re: Why does PCl5 break the Octet Rule?

Posted: Mon Nov 05, 2018 3:37 pm
by Anand Narayan 1G
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.

Re: Why does PCl5 break the Octet Rule?

Posted: Mon Nov 05, 2018 8:42 pm
by Aleeque Marselian 1A
Phosphorous, Chlorine, and Sulfur can accommodate more than eight electrons and therefore break the octet rule because they contain a 3d orbital.

Re: Why does PCl5 break the Octet Rule?

Posted: Mon Nov 05, 2018 9:51 pm
by Yixiao Hu 3C
because it is on the period 3, so it order to have the lowest energy structure, the pcl5 can break the octet rule.

Re: Why does PCl5 break the Octet Rule?

Posted: Mon Nov 05, 2018 10:21 pm
by Jayde Felix 4H
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.