Plutonium.

The study of man-made elements was critical in World War II. There was a need for a radioactive material to use in an atomic weapon, but not for material so radioactive it would disintegrate before the bomb could be made and dropped. The Radiation Laboratory (later the Lawrence Berkeley Lab) at the University of California, Berkeley, succeeded by producing plutonium. With a half-life (the time it takes for half of it to undergo radioactive decay) of twenty-four thousand yearsit allowed plenty of time to make a bomb. Plutonium, element 94 on the periodic table of the elements, was one of ten man-made elements produced by the Radiation Laboratory. The Berkeley based scientists produced all but one of the man-made elements (from 93 to 103). Swedish scientists made element 102, nobelium.

A New Element.

Element 103, lawrencium, was formed in 1961. The Berkeley group took some nickel foil, coated it...