Artificial radioactive element 1934 France scientist F. Jorio Curie and 1. Jorio Curie Found manual radioactivity It opens the way for the artificial acquisition of radioactive elements. 1937 Italy Mineralogist C. Pellier and U.S.A physical scientist E. G. Segre in University Of California Lawrence Berkeley Laboratory use cyclotron The accelerated deuteron bombarded the molybdenum target and synthesized technetium through the following nuclear reaction 98Mo (d, n) 99Tc, which is the first element manufactured artificially by human beings. 1940 American scientist D R. Kosen et al. used accelerated alpha particles to bombard bismuth targets and synthesized element 85 Astatine 。 In the same year, American chemist E. M. Macmillan Neptunium G. T. Sieberg When plutonium is found, it starts Transuranic element Synthesis of. Over the past 40 years, more than a dozen transuranic elements have been successively synthesized and further developed Periodic system of elements 。 The discovery and important properties of artificial radioactive elements are shown in the table. [2] Artificial radioactive elements are synthesized by artificial nuclear reaction. The methods of synthesis are:
① reactor Neutron irradiation synthesis nuclide Yes, 257 is the only one that can be weighed Transuranic element Method. 
Artificial radioactive element ③ Accelerating particle bombardment synthesis with accelerator, particles bombard targets made of various heavy elements, and most transuranium elements can be synthesized through nuclear reaction.
④ Thermonuclear explosion synthesis: the uranium core in the thermonuclear explosive device captures neutrons for many times in about 10-7~10-8 seconds, forming extremely neutron rich uranium isotopes, and then through a series of beta decay, heavy transuranium elements can be obtained.
Technetium
Technetium (d é) is the first artificial method element The main source is uranium fission products in the reactor. Until the early 1980s, technetium was not found naturally on the earth. use hydrogen Technetium metal can be obtained by reducing technetium sulfide (Tc2S7) or ammonium pertechnetate at 500~600 ℃. Technetium metal can also be separated by electrolysis of ammonium pertechnetate in sulfuric acid solution. Properties of technetium and its homologous elements rhenium be similar. Technetium and oxygen form volatile oxide Tc2O7 at high temperature. Tc-97 half life 2.6 million years, which can be used as a standard source for preparing beta rays. A small amount of (about 5 × 10 ^ (- 5) mol) ammonium pertechnetate can greatly slow down the corrosion of steel. Technetium and Technetium Molybdenum alloy With good superconductivity nature. Before 1960, technetium could only be produced in small quantities, and the price was as high as 2800 dollars/gram; At the end of 1970s, it was able to produce in kilogram scale, and the price has dropped to below 60 dollars/gram. At the beginning of the 21st century, technetium has reached the output of tons, which is extracted from the fission products of nuclear fuel. Technetium metal is antioxidant and has little solubility in acid, so it can be used as atomic energy Industrial equipment Anticorrosive materials 。 The metal is silvery white, but usually gray powder is obtained. Slow tarnish in humid air oxygen Medium combustion, soluble in nitric acid And sulfuric acid. Technetium is the lightest known unstable on earth isotope Chemical elements of. [3] Curium
By bombarding plutonium with helium nuclei atom Made. Curium radioactivity So strong that it sparkles in the dark. Curium, Atomic number 96, in memory of famous scientists Curie couple It gets its name. 1944 American scientists Sieberg 32M for James, etc Electron volt Of Alpha particle bombardment Plutonium 239 Found at Curium 242 , now found Mass number 238-251. The discovery of curium preceded that of americium, the element 95. plutonium
Plutonium (Pu) is a radioactive element , Yes atomic energy An important raw material for industry, which can be used as nuclear fuel and nuclear weapon Fission agent. Invest in Nagasaki The plutonium is used to make the core of the atomic bomb. It is also radio isotope The heat source of the thermal motor. Plutonium was first found in the United States in December 1940 University of California, Berkeley and Lawrence Berkeley National Laboratory Is synthesized [1-4]. Participants in the synthesis include Nobel Prize winners Sieberg (President Berkeley) [1-2] and Nobel Prize winner Edwin McMillan Et al. [1-2]. Americium
Americium has atomic number 95, which is the third element Transuranic element By the United States at the end of 1944 University of California, Berkeley Nuclear physics [1-2], chemist Sieberg And his colleagues [3] -- James, Morgan and Giosso [2] [5] first completed by et al. They named this new element America americium , element symbol is Am. [1] application
Artificial radioactive element
