## Why does PCl5 break the Octet Rule?

$FC=V-(L+\frac{S}{2})$

AJ Manzano 3K
Posts: 16
Joined: Fri Sep 28, 2018 12:25 am

### Why does PCl5 break the Octet Rule?

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_4L
Posts: 57
Joined: Fri Sep 28, 2018 12:28 am

### Re: Why does PCl5 break the Octet Rule?

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
Posts: 60
Joined: Fri Sep 28, 2018 12:19 am

### Re: Why does PCl5 break the Octet Rule?

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
Posts: 89
Joined: Thu Jun 07, 2018 3:00 am

### Re: Why does PCl5 break the Octet Rule?

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
Posts: 66
Joined: Fri Sep 28, 2018 12:15 am

### Re: Why does PCl5 break the Octet Rule?

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

Anand Narayan 1G
Posts: 61
Joined: Fri Sep 28, 2018 12:15 am

### Re: Why does PCl5 break the Octet Rule?

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
Posts: 60
Joined: Fri Sep 28, 2018 12:24 am

### Re: Why does PCl5 break the Octet Rule?

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: Fri Sep 28, 2018 12:19 am

### Re: Why does PCl5 break the Octet Rule?

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: Fri Sep 28, 2018 12:28 am

### Re: Why does PCl5 break the Octet Rule?

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.