Expanded Valence Shells

[Katherine Grillo 1B]

Which atoms accommodate more than 8 valence electrons? And why? I know that P, S, and Cl have expanded valence shells but why? And what are the others that have expanded valence shells?

[Rian Montagh 2K]

Elements in period three and above have expanded octets because they have access to the d orbitals for extra e- to go into.

[Faith Fredlund 1H]

You can tell that period 3 allows for an expanded octet when forming bond because of its angular momentum quantum number (l). Because it has a principle quantum number of n=3, this means that possible values for l include l= 0, 1, 2 which correspond to s=0, p=1, and d=2 orbitals. d-orbitals allow for an expanded octet because they can accommodate 10 electrons.

[Karan Thaker 2L]

That's the same methodology I use when I get confused ^ ... I often forget which atoms are capable of forming more than an octet and can have expanded shells and simply think of the possible values based on quantum number. It always ends up making sense and working out.