Symbol Name Atomic Number Atomic Weight Group Number
Pu Plutonium 94 244


Standard State: Solid at 298 K
Color: Silvery white

Plutonium was the second transuranium element of the actinide series to be discovered.   The isotope 238Pu was produced by Seaborg, McMillan, Kennedy, and Wahl by deuteron bombardment of uranium in the 60-inch cyclotron at Berkeley, California. Plutonium also exists is trace quantities in naturally occurring uranium ores.   Plutonium has been used in the Apollo lunar missions to power seismic and other equipment on the lunar surface.  Plutonium can be prepared by the reduction of trifluoride with the alkaline-earth metals.  Plutonium is very dangerous because it is a radiological hazard.  Precautions must be taken to prevent the unintentional formation of a critical mass.