It is chemically reactive. A relatively large piece of plutonium is warm to the touch because of the energy given off in alpha decay. Larger pieces will produce enough heat to boil water. The metal exhibits six allotropic modifications having various crystalline structures. Because of the high rate of emission of alpha particles and the element being specifically absorbed by bone marrow, plutonium, as well as all of the other transuranium elements except neptunium, are radiological poisons and must be handled with very special equipment and precautions.
Plutonium is a very dangerous radiological hazard.
Precautions must also be taken to prevent the unintentional formation of a critical mass. Plutonium in liquid solution is more likely to become critical than solid plutonium. The shape of the mass must also be considered where criticality is concerned. C Chemical and Physical Properties Plutonium exists as a number of isotopes. 242,244 Plutonium exhibits six allotropic forms and four valence states.