Octet Exeptions

[Sahra Sutaria]

Hi!
As I was going through the textbook and the included problems I realized I did not understand the reasoning behind why sulfur can have an expanded octet when it is the central atom but Nitrogen or Carbon as central atoms cannot. Could someone please explain.

Here is the problem that prompted this question:
Draw the lewis structure for BrF3 and ONF.

Thanks Sahra.

[Habin Yoo_2D]

Nitrogen and Carbon are the atoms that are in 2nd period. However, Sulfur is in the third period. Atoms in the 2nd period are too small to have electrons more than 8 electrons.

[Nathan Huon 2C]

Sulfur has an available 3d orbital that can have extra electrons, allowing it to have an expanded octet.