Exceptions

[Lopez_Melissa-Dis4E]

How are H, He, Li, Be exceptions to the octet rule? What does this mean? If we went over it in class, I totally missed it.

[Karishma_1G]

Yes, I have the same question! If someone could explain, that would be great!

[Beatrice Petelo 1F]

Octet rule --> atoms completing their octets (noble-gas configuration) by sharing electron pairs

H, He, Li, and Be are exceptions to the rule, meaning that they do not need the complete set of 8 electrons around them.

Be and B commonly form compounds in which the central atom has fewer than four pairs of valence e-. (ex: BH2: H-B-H)
H and He are most stable when they have two electrons

[Alexandra Ortega 4D]

H, He, Li, and Be are exceptions to the octet rule because they only have electrons in the s orbital so the maximum amount of electrons they can have in their outer shell is 2. Therefore, they will never be able to have 8 valence electrons.

[Kelly Hollman]

They don't have "space" to fill an octet. They only have room for 2 electrons in the outershell as they have S orbitals only!