Section 6
Exceptions to the Octet Rule
Book
Version 33
By Boundless
By Boundless
Boundless Chemistry
Chemistry
by Boundless
3 concepts
![Thumbnail](../../../../../../figures.boundless-cdn.com/9728/square/bf3-20and-20bf3nh3.jpg)
The Incomplete Octet
While most elements below atomic number 20 follow the octet rule, several exceptions exist, including compounds of boron and aluminum.
![Thumbnail](../../../../../../figures.boundless-cdn.com/9777/raw/nitric-oxide.jpg)
Odd-Electron Molecules
Molecules with an odd number of electrons disobey the octet rule.
![Thumbnail](../../../../../../figures.boundless-cdn.com/9793/square/entachloride-2d-dimensions.jpg)
The Expanded Octet
Main group elements in the third period and below form compounds that deviate from the octet rule by having more than 8 valence electrons.