Clarification on Expanded Octets

[TiffanyBrownfield 2I]

Can someone expand on what having an expanded octet means? I know it has to do with utilizing the d-subshell, and therefore the bonding atom can have more than 8 valence electrons. However I'm still slightly confused about how many valence electrons each atom (with an expanded octet) can have?

[Anh Trinh 1J]

An expanded octet is when the central atom in a molecule has empty d-orbitals close in energy to the valence orbitals, and so it may be able to accommodate 10, 12, or even more electrons. Only p-block atoms in Period 3 or later periods can expand their valence shells. Atoms of these elements have empty d-orbitals in the valence shell.

[George Hernandez 3I]

Instead of creating concentrated pairs of electrons, the atom instead spreads out its electrons over multiple orbitals in the d-subshell, creating multiple extra bonds to be used. More atoms are capable of expanded octets than those that aren't. It's the norm, not the exception. :)

[Mackenzie Stockton 2H]

Expanded octet just means that an atom utilizes its d block to hold more than 8 electrons in the valence, which is not possible with only s and p orbitals.

The common expanded octets are P, S, Cl.

Any atom in row 3 of the periodic table (in the p block) and below, can have an expanded octet because of the utilization of the d block.