Expanded Octets

[Sean Phen]

How do you know which elements are able to have expanded octets?

[Jessica Katz]

They are the elements that occupy enough orbitals to accommodate a larger amount of electrons around the central atom like Xe or P.

[Selena Quispe 2I]

Expanded octets can happen for atoms in period 3 and below. This happens when you have a full octet on the atoms in the lewis dot structure but still have left over electrons. For example, BrF3 has an expanded octet. The fluorines have a complete octet and so does bromine but there are still left over electrons so the Bromine will have the four remaining electrons bonded to it giving it a total of 10 electrons (which is allowed as it is below the third period). I hope this helps!

[Vanshika Bhushan 1A]

An element from Period 3 and below is able to expand octet by making use of its low lying d-subshell for bonding.

This means only Period 2 elements such as C, N, O and F cannot expand octet and have to obey octet rule.

[Nan_Guan_1L]

Just to add on to the discussion above, I think it's atoms in period 3 or higher have d-orbitals in their valence shells, so they can accommodate additional electrons.

[AndrewNguyen_2H]

Elements beyond the n=2 principal number have expanded because their electrons can move to the d orbitals.