plutónium

Plutonium (symbol Pu, atomic number 94) is a radioactive actinide metal. In its pure form it is a silvery metal that slowly tarnishes in air, forming a thin oxide layer. It exhibits several oxidation states, commonly from +3 to +7, with PuO2 being the most stable oxide. The most technologically important isotopes are Pu-238, Pu-239, Pu-240, and Pu-241. Pu-239 is fissile and has been used for nuclear weapons and as a reactor fuel; Pu-238 is a strong alpha emitter with a half-life of 87.7 years and powers space missions via radioisotope thermoelectric generators; Pu-241 decays to Am-241 and contributes to heat and radiation.

Discovery and naming: plutonium was first synthesized in 1940 at the University of California, Berkeley, by Glenn T. Seaborg, Edwin M. McMillan, Joseph W. Kennedy, and Arthur Wahl. It was named after the planet Pluto, in line with the practice of naming nearby actinides after celestial bodies.

Production: plutonium is produced commercially mainly by irradiating uranium-238 in nuclear reactors and subsequently separating plutonium chemically from irradiated fuel.

Applications and safety: Pu-239-based materials have been used in nuclear weapons and in mixed-oxide fuels (MOX) for reactors. Pu-238 is used in space probes and rovers for power. Handling plutonium requires stringent safeguards due to its radiological and chemical toxicity; it is an alpha emitter with long half-lives, posing long-term environmental concerns if released.