Exceptions to Octet

[Rachel-Weisz3C]

Can someone explain the reason to why H, He, Li, and Be are the exceptions to the octet rule?

[804994652]

H and He are in the 1s shell which only need 2 e- to be a full shell. Li and Be are metals who tend to lose electrons and become the "noble gas" configuration of He (1s shell).

[Ethan Yi 1K]

It's easier for Li and Be to become stable by losing 1 or 2 electrons respectively and becoming like the noble gas He, rather than gaining 6 or 7 electrons to become like Neon.