Plutonium

Plutonium is a radioactive element that is represented on the periodic table by a Pu and has an atomic number of 94. It has a silver appearance that tarnishes when exposed to air, it oxidizes it forms oxides and hydrides that expand up to 70% in volume, the oxidized Plutonium can flake off into powder that can spontaneously ignite.
 * Over 1/3 of the energy produced in most nuclear power plants comes from plutonium, and the reactor creates it as a by-product.
 * Plutonium has occurred naturally, but except for trace quantities, it is not found in the Earth's crust.
 * There are several tonnes of plutonium in our biosphere, a legacy of atmospheric weapons testing in the 1950s and 1960s.

There are two types of plutonium: reactor-grade and weapons-grade. The first is recovered as a by-product of a nuclear reactor, and the second is made specially for the military purpose and is recovered from uranium fuel that has been irradiated for 2-3 months in a plutonium production reactor. These two types each differ in their isotopic composition, but both are recognized as being dangerous.

Plutonium, like most metals, has a bright silvery appearance at first, much like nickel, but it oxidizes very quickly to a dull gray, although yellow and olive green are also reported. At room temperature plutonium is in its α form (//alpha//). This, the most common structural form of the element ( allotrope ), is about as hard and brittle as grey cast iron unless it is alloyed with other metals to make it soft and ductile. Unlike most metals, it is not a good conductor of heat or electricity. It has a low melting point (640 °C) and an unusually high boiling point (3,228 °C). Alpha decay, the release of a high-energy helium nucleus, is the most common form of radioactive decay for plutonium. A 5 kg mass of 239Pu contains about 12.5 × 1024 atoms. With a half-life of 24,100 years, about 11.5 × 1012 of its atoms decay each second by emitting a 5.157 MeV alpha particle. This amounts to 9.68 watts of power. Heat produced by the deceleration of these alpha particles makes it warm to the touch. Resistivity is a measure of how strongly a material opposes the flow of electric current. The resistivity of plutonium at room temperature is very high for a metal, and it gets even higher with lower temperatures, which is unusual for metals. This trend continues down to 100 K, below which resistivity rapidly decreases for fresh samples. Resistivity then begins to increase with time at around 20 K due to radiation damage, with the rate dictated by the isotopic composition of the sample. Because of self-irradiation, a sample of plutonium fatigues throughout its crystal structure, meaning the ordered arrangement of its atoms becomes disrupted by radiation with time. Self-irradiation can also lead to annealing which counteracts some of the fatigue effects as temperature increases above 100 K. Unlike most materials, plutonium //increases// in density when it melts, by 2.5%, but the liquid metal exhibits a linear decrease in density with temperature. Near the melting point, the liquid plutonium has also very high viscosity and surface tension as compared to other metals.
 * Properties Of Plutonium**

Plutonium is used as an explosive in nuclear weapons. The complete detonation of a kilogram of plutonium produces an explosion equal to that produced by approximately 20,000 tons of chemical explosive. One kilogram of plutonium is equivalent to 22 million kilowatt hours of heat energy, so plutonium is important for nuclear power. Source:[]
 * __Various Uses for Plutonium__**

Radioactive and Artificially Produced Plutonium was first produced by Glenn T. Seaborg, Joseph W. Kennedy, Edward M. McMillan and Arthur C. Wohl by bombarding an isotope of uranium, uranium-238, with deuterons that had been accelerated in a device called a cyclotron. This created neptunium-238 and two free neutrons. Neptunium-238 has a half-life of 2.1 days and decays into plutonium-238 through beta decay. Although they conducted their work at the __University of__ California in 1941, their discovery was not revealed to the rest of the scientific community until 1946 because of wartime security concerns. Plutonium's most stable isotope, plutonium-244, has a half-life of about 82,000,000 years. It decays into uranium-240 through alpha decay. Plutonium-244 will also decay through spontaneous fission. Only two of plutonium's isotopes, plutonium-238 and plutonium-239, have found uses outside of basic research. Plutonium-238 is used in radioisotope thermoelectric generators to provide electricity for space probes that venture too far from the sun to use __solar__ power, such as the Cassini and Galileo probes. Plutonium-239 will undergo a fission chain reaction if enough of it is concentrated in one place, so it is used at the heart of modern day nuclear weapons and in some nuclear reactors.
 * Atomic Number:** 94
 * Atomic __Weight__:** 244
 * Melting Point:** 913 K (640°C or 1184°F)
 * Boiling Point:** 3501 K (3228°C or 5842°F)
 * Density:** 19.84 grams per cubic centimeter
 * Phase at Room Temperature:** Solid
 * Element Classification:** Metal
 * Period Number:** 7 **Group Number:** none **Group Name:** Actinide
 * What's in a name?** Named for the dwarf planet **Pluto**.
 * Say what?** Plutonium is pronounced as **ploo-TOE-nee-em**.
 * History and Uses:**
 * Estimated Crustal Abundance:** Not Applicable
 * Estimated Oceanic Abundance:** Not Applicable
 * Number of Stable Isotopes:** 0
 * Ionization Energy:** 6.06 eV
 * Oxidation States:** +6, +5, +4, +3

Isotopes and compounds of plutonium are radioactive and accumulate in bone marrow. Contamination by plutonium oxide has resulted from a number of nuclear disasters and radioactive incidents including military nuclear accidents where nuclear weapons have burned. Studies of the effects of these smaller releases, as well as of the widespread radiation poisoning sickness and death following the atomic bombings of Hiroshima and Nagasaki, have provided considerable information regarding the dangers, symptoms and prognosis of radiation poisoning. During the decay of plutonium, three types of radiation are released—alpha, beta, and gamma. Alpha radiation can travel only a short distance and cannot travel through the outer, dead layer of human skin. Beta radiation can penetrate human skin, but cannot go all the way through the body. Gamma radiation can go all the way through the body. Alpha, beta, and gamma radiation are all forms of ionizing radiation. Either acute or longer-term exposure carries a danger of serious health outcomes including radiation sickness, genetic damage , cancer, and death. The danger increases with the amount of exposure. Even though alpha radiation cannot penetrate the skin, ingested or inhaled plutonium does irradiate internal organs. The skeleton, where plutonium is absorbed, and the liver, where it collects and becomes concentrated, are at risk. Plutonium is not absorbed into the body efficiently when ingested; only 0.04% of plutonium oxide is absorbed after ingestion. Plutonium absorbed by the body is excreted very slowly, with a biological half-life of 200 years. Plutonium passes only slowly through cell membranes and intestinal boundaries, so absorption by ingestion and incorporation into bone structure proceeds very slowly. Plutonium is more dangerous when inhaled than when ingested. The risk of lung cancer increases once the total radiation dose equivalent of inhaled plutonium exceeds 400 mSv. The U.S. Department of Energy estimates that the lifetime cancer risk from inhaling 5,000 plutonium particles, each about 3 microns wide, to be 1% over the background U.S. average. Ingestion or inhalation of large amounts may cause acute radiation poisoning and death; no human is known to have died because of inhaling or ingesting plutonium, and many people have measurable amounts of plutonium in their bodies. The inhalation hazard is about 23,000 times greater than that of weapons-grade uranium, the ingestion hazard about 130,000 times greater. For each milligram in oxide form inhaled by an exposed population, an excess 3 to 12 cancer deaths is expected. The "hot particle" theory in which a particle of plutonium dust radiates a localized spot of lung tissue has been tested and found false—such particles are more mobile than originally thought and toxicity is not measurably increased due to particulate form. When inhaled plutonium can pass into the bloodstream. Once in the bloodstream, plutonium moves throughout the body and into the bones, liver, or other body organs. Plutonium that reaches body organs generally stays in the body for decades and continues to expose the surrounding tissue to radiation and thus may cause cancer.
 * Danger - Toxicity**

History
Enrico Fermi and a team of scientists at the University of Rome reported that they had discovered element 94 in 1934 The sample was actually a mixture of barium, krypton, and other elements, but this was not known at the time because nuclear fission had not been discovered yet. Plutonium (specifically, plutonium-238) was first produced and isolated on December 14, 1940, and chemically identified on February 23, 1941, by Dr. Glenn T. Seaborg, Edwin M. McMillan, J. W. Kennedy, and A. C. Wahl by deuteron bombardment of uranium in the 60-inch (150 cm) cyclotron at the University of California, Berkeley A paper documenting the discovery was prepared by the team and sent to the journal //Physical Review// in March 1941. Edwin McMillan had recently named the first transuranium element after the planet Neptune and suggested that element 94, being the next element in the series, be named for what was then considered the next planet, Pluto Seaborg originally considered the name "plutium", but later thought that it did not sound as good as "plutonium." He chose the letters "Pu" as a joke, which passed without notice into the periodic table. Alternative names considered by Seaborg and others were "ultimium" or "extremium" because of the erroneous belief that they had found the last possible element on the periodic table.