A century ago, the periodic table looked much different than it does today! It had blank spots throughout, and the entire bottom row – the actinides – were not even part of the table as they had not been discovered yet.

But researchers theorized their existence. And starting in the 1930s scientists at Lawrence Berkeley National Laboratory – or, the Rad Lab, as it was called then – began building the big machines and assembling the teams of scientists and engineers to chase those elements down. Over the next several decades Berkeley Lab researchers were credited in the discovery of 16 elements. Read more here.