Final answer:
The expansion of the valence shell to accommodate more than eight electrons is associated with covalent bonding in expanded octet molecules, not seen in ionic bonding.
Step-by-step explanation:
The expansion of the valence shell to accommodate more than eight electrons is specifically associated with covalent bonding and is typically seen in expanded octet molecules. Such molecules commonly have a central atom from the third period of the periodic table or beyond, for example, phosphorus in PF5, which have extra d orbitals in their valence shell allowing them to form more than the standard four covalent bonds. In ionic bonding, atoms transfer electrons to attain full valence shells, commonly achieving the octet configuration, whereas covalent bonding involves the sharing of electron pairs between atoms.