Plutonium is the most economically important of the transuranic elements. Plutonium-239 readily undergoes fission, and it is used for nuclear weapons and for energy. The atomic number of plutonium is 94. Isotopes of plutonium were first prepared and studied by the American chemist Glenn T. Seaborg and his associates at the University of California at Berkeley in 1941. Plutonium has 15 isotopes with mass numbers ranging from 232 to 246.
All isotopes of plutonium are radioactive, but they have widely varying half-lives.
The half-life is the time it takes for half the atoms of an element to decay. The various isotopes also have different principal decay modes. The most important isotope of plutonium is Pu-239. It's virtually nonexistent in nature. It is produced by bombarding uranium-238 with slow neutrons.