Octet Exception

[Maverick Tan 1F]

Can someone please explain how the elements Li, and Be, are an exception to the octet rule?

[Jennifer_Wong_1G]

For period 2 elements to obey the octet rule, they need to complete their valence shell with eight electrons. Li and Be follow the octet rule when they ionize, but they are exceptions to the octet rule when they form covalent compounds. This is because they don't have enough valence electrons to form four electron-pair bonds. Lithium has one valence electron and so is most stable when it gives up an electron. Beryllium has two valence electrons but can only form electron pair bonds in two locations.

Hope this helps!