Fission The process of using a neutron to split

First law of thermodynamics the energy of the universe is constant same as the law of conservation of energy. (9.1) Fission the process of using a neutron to split a heavy nucleus into two nuclei with smaller mass numbers. (21.6) Formal charge the charge assigned to an atom in a molecule or polyatomic ion derived from a specific set of rules. (13.12) Formation constant (stability constant) the equilibrium constant for each step of the formation of a complex ion by the addition of an individual ligand to a metal ion or complex ion in aqueous solution. (8.9)... 

First law of thermodynamics the energy of the universe is constant same as the law of conservation of energy. (9.1) Fission the process of using a neutron to split a heavy nucleus into two nuclei with smaller mass numbers. (20.6)... 

Fission the process of using a neutron to split a heavy nucleus into two nuclei with smaller mass numbers. (19.6)... 

When neutrons strike the nucleus of a large atom, they cause that nucleus to split apart into two roughly equal pieces known as fission products. In that process, additional neutrons and very large amounts of energy are also released. Only three isotopes are known to be fissionable, uranium-235, uranium-233, and plutonium-239. Of these, only the first, uranium-235, occurs naturally. Pluto-nium-239 is produced synthetically when nuclei of uranium-238 are struck by neutrons and transformed into plutonium. Since uranium-238 always occurs along with uranium-235 in a nuclear reactor, plutonium-239 is produced as a byproduct in all commercial reactors now in operation. As a result, it has become as important in the production of nuclear power as uranium-235. Uranium-233 can also be produced synthetically by the bombardment of thorium with neutrons. Thus far, however, this isotope has not been put to practical use in nuclear reactors. 

In Germany in 1938, Otto Hahn and Fritz Strassmann, skeptical of claims by Enrico Fermi and Irene Johot-Curie that bombardment of uranium by neutrons produced new so-called transuranic elements (elements beyond uranium), repeated these experiments and chemically isolated a radioactive isotope of barium. Unable to interpret these findings, Hahn asked Lise Meitner, a physicist and former colleague, to propose an explanation for his observations. Meitner and her nephew, Otto Frisch, showed that it was possible for the uranium nucleus to be split into two smaller nuclei by the neutrons, a process that they termed fission. The discovery of nuclear fission eventually led to the development of nuclear weapons and, after World War II, the advent of nuclear power to generate electricity. Nuclear chemists were involved in the chemical purification of plutonium obtained from uranium targets that had been irradiated in reactors. They also developed chemical separation techniques to isolate radioactive isotopes for industrial and medical uses from the fission products wastes associated with plutonium production for weapons. Today, many of these same chemical separation techniques are being used by nuclear chemists to clean up radioactive wastes resulting from the fifty-year production of nuclear weapons and to treat wastes derived from the production of nuclear power. 

Fast Reactor An advanced technology nuclear reactor that uses a fast fission process utilizing fast neutrons that would split some of the U-258 atoms as well as transuranic isotopes. The goal is to use nuclear material more efficiently and safely in the production of nuclear energy. 

Nuclear fission is a process in which the nucleus of an atom splits, usually into two pieces. This reaction was discovered when a target of uranium was bombarded by neutrons. Eission fragments were shown to fly apart with a large release of energy. The fission reaction was the basis of the atomic bomb, which was developed by the United States during World War II. After the war, controlled energy release from fission was applied to the development of nuclear reactors. Reactors are utilized for production of electricity at nuclear power plants, for propulsion of ships and submarines, and for the creation of radioactive isotopes used in medicine and industry. 

Uranium fission caused by neutrons was forced or artificial. Not each uranium nucleus could be split and not each neutron could produce fission. When scientists had studied the fission mechanism in more detail they understood that the intensity of fission was higher under the effect of slow neutrons and if the uranium isotope with a mass number of 235 was used. The other uranium isotope, uranium-238, experienced fission only when bombarded by fast neutrons. Can there be a natural process similar to artificial uranium fission N. Bohr thought about that and put forward a hypothesis about possible spontaneous uranium fission (without external energy being transferred to the nuclei). 

During spontaneous nuclear fission reactions, heavy nuclei split when bombarded by neutrons, and release large amounts of energy. This process was used to produce two atomic bombs whose use ended World War II. A second energy-releasing nuclear process, fusion, is the basis for today s hydrogen bombs. Nuclear fission is in limited use as a source of electrical power however, this use is controversial. Nuclear fusion has not yet proved feasible as a controlled source of power, but research toward this end continues. 

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