Which elements are capable of octet exceptions?

[Ryan M]

Is it really anything in row 3 and beyond? If so, is there an easier way to tell which elements are most likely to take on 5+ bonds? The only ones I know off the top of my head are sulfur and xenon.

[KatieFrancisco1F]

Yes it is anything row 3 and below. The octets will be expanded when it is most convenient for the molecule to have a formal charge of 0 (or lowest possible). So if all the other atoms have full octets with a neutral net charge but you have leftover electrons, these can be added to your atom with the expanded octet.

[Rachel Bartley 2B]

Elements in Period 3 and below are capable of having expanded octets because they all have d-orbitals. You'll likely know when the exceptions take place as an expanded octet helps stabilize the compound by decreasing the formal charge of the central atom.

[Violet Mbela 2B]

You have to make sure that you pay attention to what orbital the element is in, because that determines how many e- it can hold.

[Sally_Luo_3F]

it has to be the p-block atoms in Period 3 or later period that can expand their shell.

[Terrence Chi]

Hi, third period and beyond exceed the octet rule because the elements can use their empty d orbitals to accommodate additional electrons (expand their shell). Hope this helps!

[Joseph Ettipio]

Adding on to the above, the most common expanded octets that you will see are phosphorus, sulfur, chlorine, and xenon. If they are forming an expanded octet, phosphorus typically forms five bonds, sulfur forms six bonds, chlorine forms seven bonds, and xenon forms eight bonds. This is because if you take formal charge calculations (valence - (dots + bonds)) into account, these elements have a 0 charge at those number of bonds.

[Luke Schwuchow 14A]

To expand on the previous responses, the p-block elements in periods 3-6 can have expanded octets, with the exception of argon and radon.

[Leah Wildmann 1F]

Any atom in 3p and on

[Andrew_Ramirez]

The elements capable of an expanded octet are anything in the 3rd period and on as well as P, S, and Cl.

[JafarriNocentelli 1G]

Any atom you see that is 3P and forwards can expand its octet

[005502505]

From my notes, there are several common exceptions to the octet rule:
Ru (has ground state configuration of [Kr] 4d^75s^1; for example, Ru3+ = [Kr]4d^5
Chromium (Cr), doesn’t have s^2; has s1
Copper (Cu) [Ar] 3d^104s^1, loses electrons from s orbital first, doesn’t have s^2; has s^1