Appearance and Characteristics
Harmful effects:
Plutonium is harmful due to its radioactivity. Plutonium and its compounds are also toxic. It collects in the bones and the liver where it can remain for a long period of time. (4)
Characteristics:
Plutonium is a silvery radioactive metal that tarnishes in air to give a yellow oxide coating. It has six allotropic forms, which vary widely in crystal structure and density. The metal is chemically reactive, forming compounds with carbon, nitrogen, and silicon and the halogens. If you were to touch a small piece of plutonium metal (please don’t!) it would feel warm because of the energy released by alpha decay. A larger piece of the metal could boil water.
Uses of Plutonium
Plutonium-239, which can undergo nuclear chain reactions, is used in nuclear bombs and nuclear reactors
Plutonium-238 is used as a long-lived heat and power source for space probes. (Its intrinsic heat output is approximately 0.5 watts per gram.) The Pioneer and Voyager space probes used plutonium-238 nuclear batteries as a power source.
Three radioisotope heater units (each containing 2.7 grams of plutonium-238 dioxide) were used as heat sources on the Pathfinder Mars robot lander. Each radioisotope heater unit produces about one watt of heat. (6), (7)
Early pacemaker batteries also used tiny amounts of plutonium-238.
The image on the left shows the decay of one atom of plutonium-238. This releases 5.6 million electron volts of energy. To get an idea of what this means, consider NASA’s Curiosity Mars rover, which will be powered by 4.8 kg of plutonium dioxide.
During its first 87.7 year half-life, the plutonium will produce about 4800 gigajoules of energy. To generate the same energy using natural gas (mainly methane) the Mars rover would need to carry about 86 metric tons of methane and 345 metric tons of oxygen.