Octet Rule Exceptions

[Ashley Tran 2I]

Why are H, He, Li, and Be exceptions for the octet rule?

[Reina Robles 2B]

They don’t need eight electrons to fill their shell. H and He only have the 1s shell, which only needs 2 electrons to fill it. Li and Be only have the 1s and 2s shell, and the 2s shell only needs two electrons to fill it.

Hope this helps!

[Justin Quan 4I]

To add on, Li and Be are metals, and so they are like to lose electrons and become cations. After they lose their electrons they revert to a noble gas configuration. Also hydrogen doesn't need to fill its valance shell when forming bonds. Hydrogen just likes to give away its lone electron.

[Sukanya Mohapatra 2G]

H and He are exceptions to the octet rule since their full shell is two electrons. Li and Be are metals, making them more likely to lose electrons and turn into cations.