Atomic nucleus nuclear fission

The burning of fossil fuel is a chemical reaction, which, as you recall from Section 2.1, is a reaction that involves changes in the way atoms are bonded and results in the formation of new materials. For fossil fuels, these new materials are mostly carbon dioxide and water vapor. As we explore in future chapters, the only thing that determines the ability of atoms to form new materials in a chemical reaction is the atoms ability to share or exchange electrons—the atomic nuclei are not directly involved. The chemistry of an atom is therefore more a function of its electrons than of its nucleus. Nuclear fission, by contrast, involves nuclear reactions, which, as shown in the chapter-opening photograph, involve the atomic nucleus. In this sense, the study of the atomic nucleus is not a primary focus of chemistry. 

The nucleus of an atom consists of protons and neutrons that are bound together by a nuclear force. Neutrons and protons are rearranged in a nuclear reaction in a manner somewhat akin to rearrang ing atoms in a chemical reaction. The nuclear reaction liberating energy in a nuclear power plant is called nuclear fission. The word fission is derived from fissure, which means a crack or a separation. A nucleus is separated (fissioned) into two major parts by bombardment with a neutron. 

In 1938 Niels Bohr had brought the astounding news from Europe that the radiochemists Otto Hahn and Fritz Strassmann in Berlin had conclusively demonstrated that one of the products of the bom-bardmeiit of uranium by neutrons was barium, with atomic number 56, in the middle of the periodic table of elements. He also announced that in Stockholm Lise Meitner and her nephew Otto Frisch had proposed a theory to explain what they called nuclear fission, the splitting of a uranium nucleus under neutron bombardment into two pieces, each with a mass roughly equal to half the mass of the uranium nucleus. The products of Fermi s neutron bombardment of uranium back in Rome had therefore not been transuranic elements, but radioactive isotopes of known elements from the middle of the periodic table. 

The process of radioactive decay (also known as radioactivity) involves the ejection from a nucleus of one or more nuclear particles and ionizing radiation. Nuclear fission is a reaction in which the nucleus splits into smaller nuclei, with the simultaneous release of energy. Most radioisotopes undergo radioactive decay processes and are converted into different smaller atoms. 

Neutrons have no electrical charge and have nearly the same mass as a proton (a hydrogen atom nucleus). A neutron is hundreds of times larger than an electron, but one quarter the size of an alpha particle. The source of neutrons is primarily nuclear reactions, such as fission, but they are also produced from the decay of radioactive elements. Because of its size and lack of charge, the neutron is fairly difficult to stop, and has a relatively high penetrating power. 

A heavy nucleus can split into lighter nuclei by undergoing nuclear fission. Nuclear power plants use controlled nuclear fission to provide energy. Uncontrolled nuclear fission is responsible for the massive destructiveness of an atomic bomb. 

Nuclear Fission the splitting of the nucleus of an atom of a heavier element into smaller nuclei to produce energy in a nuclear reaction... 

Nuclear flssion Nuclear fission, the splitting of an atomic nucleus, doesn t occur in nature. Humans first harnessed the tremendous power of fission during the Manhattan Project, an intense, hush-hush effort by the United States that led to the development of the first atomic bomb in 1945. Fission has since been used for more-benign purposes in nuclear power plants. Nuclear power plants use a highly regulated process of fission to produce energy much more efficiently than is done in traditional, fossil fuel-burning power plants. 

Fission Reaction. In nuclear fission, the nucleus of a heavy atom is split into tv/o or more fragments. The reaction is initiated by the absorption of a neutron. A typical reaction is... 

Nuclear reactors harness the energy from the fission of uranium-235. Nuclear fission occurs when the unstable nucleus of a radioactive isotope splits up, forming smaller atoms and producing a large amount of energy as a result. Scientists believe that the energy comes from the conversion of some of the mass of the isotope. 

As opposed to nuclear fission, nuclear fusion is the reaction when two light atomic nuclei fuse together, forming a heavier nucleus. That nucleus releases energy. So far, fusion power generators bum more energy than they create. However, that may change with the construction of the International Thermonuclear Experimental Reactor (ITER) in Southern France. To be completed in 2016 at a cost of about 11.7 billion, the reactor is a pilot project to show the world the feasibility of full-scale fusion power. 

Nuclear Explosions Although conventional explosives have become the weapons of choice of terrorist groups, a joint report issued in 2008 by Harvard s Kennedy School of Government and the Nuclear Threat Initiative reminds us that there is a real danger that terrorists could get and use a nuclear weapon.16 In order to understand what this would mean, we return to the atomic nucleus. A nuclear fission reaction releases far more energy than any ordinary chemical process. The Oklahoma City bomb was equivalent to the explosion of approximately 40001b of TNT.17 In contrast, the atomic bomb dropped on... 

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