Pentbiunium (Pbu)

Pentbiunium is the systematic name of the theoretical 521e element in the periodic table with a symbol of Pbu and atomic number of 521. Pentbiunium, also known as element 521, has vijf­honderd­een­en­twintig protons in its nucleus, and vijf­honderd­een­en­twintig electrons in its shells.