ELI5: How is Palladium able to cram all its electrons into it's first 4 valence shells, but the elements both above AND below it are forced to use their 5th shell? :
EXPLANATION OF PALLADIUM IONIZATIONS | Lefteris Kaliambos Wiki | Fandom
Atom of Palladium with Core and 46 Electrons on Black Stock Illustration - Illustration of scheme, nuclear: 251707411