Hans Geiger was a German physicist. He was born in 1882 at Neustadt-an-der- Haardt and died in 1945. He studied at Erlangen and moved to Manchester where he worked under Ernest Rutherford from 1906 to 1912. He investigated beta-ray radioactivity, and helped to devise a counter to measure it (the geiger counter). He was professor at Kiel in 1925 and at Tubingen in 1929 and later worked at Berlin. Research Hans Geiger
Plutonium is a radioactive metal element with the symbolPu. It was discovered by the chemists Glenn Seaborg and Edwin McMillan in 1940. The isotopes of plutonium were first prepared and studied by Seaborg and his associates in 1941. Trace amounts of the element have since been found in uranium ores, but plutonium is prepared in relatively large quantities today in nuclear reactors. Chemically, plutonium is reactive, its properties somewhat resembling those of the rare earth elements. The silvery metal, which becomes slightly yellow through oxidation caused by exposure to air, exists in six varying crystalline forms and has four different oxidation states. The metal gives off heat because of its radioactivity ; 15 different isotopes of
plutonium, ranging in mass number from 232 to 246, are known.
Plutonium-239 has a half-life of 24,360 years, and is produced by bombarding uranium-238 with slow neutrons. This forms neptunium-239, which in turn emits a beta particle and forms plutonium-239.
Plutonium is the most economically important of the transuranium elements because plutonium-239 readily undergoes fission and can be both used and produced in quantity in nuclear reactors. It is also used in making nuclear weapons. It is an extremely hazardous poison due to its high radioactivity. Plutonium-238 has been used to power equipment on the moon by means of the heat it emits. Research Plutonium
Radioactivity is the spontaneous disintegration of an atomic nucleus to produce more stable nucleus and accompanied by the emission of charged particles and possibly also gamma rays. Research Radioactivity
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Abbreviations
Research Hans Geiger
