1 jan 1944 ano - The Modern Periodic Table (1944)

Descrição:

Glenn T. Seaborg moved heavy elements to the bottom of the table. On the modern periodic table, there are two rows and fourteen columns separate from the rest of the elements. Seaborg saw that these two series, called the lanthanide series and the actinide series, belonged next to the transition metal block of the periodic table.

Adicionado na linha do tempo:

Data: