Chapter 13 Nuclear Reactions: Notes

Chapter 13 Nuclear Reactions: Notes - Chapter 13 Nuclear...

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Chapter 13 Nuclear Reactions: Notes 1. alpha particle – Ernest rutherford studied the nature of radioactivity and found there are thee kinds, alpha, beta, and gamma radiation. known to be the nucleus of a helium atom. Two protons and two neutrons. 2. background radiation – Radiation from natural sources. Comes from outer space in the form of cosmic rays and from unstable isotopes in the ground, building materials, and foods. Consequences of radiation exposure can (1) Disrupt chemical bonds in essential macromolecules such as DNA and (2) produce molecular fragments, which are free polyatomic ions that can interfere with enzyme action and other essential cell functions. 3. band of stability – The number of protons increase the neutron-to-proton ratio of the stable nuclei also increases in a band of stability. Within the band the neutron-to-proton ratio increases from 1:1 at the bottom left to 1 ½ at the top right. Increased ratio of neutrons is needed to produce a stable nucleus as the number of protons increases. Neutrons provide additional attractive nuclear forces which counter the increased electrical repulsion from a larger number of positively charged protons. 4. beta particle – high-energy electron. (beta-ray) 5. binding energy – energy required to break the nucleus into individual protons and neutrons. Energy equivalent released when a nucleus is formed is the same as the binding energy. 6. chain reaction – A reaction where the products are able to produce more reactions in a self sustaining series. This is self sustaining until all the uranium-235 nuclei have fissioned or until the neutrons fail to strike a uranium-235 nucleus. 7. control rods – Constructed of materials such as cadmium that absorb neutrons. Lowering or raising of control rods within the fuel rod assemblies slows or increases the chain reaction by varying the amount of neutrons absorbed. When lowered completely into the assembly enough neutrons are absorbed to stop the chain reactions. 8. critical mass – To achieve a chain reaction there bust be 91) sufficient mass with (2) a sufficient concentration of fissionable nuclei. When the mass and concentration are sufficient to sustain a chain reaction the amount is called a critical mass. A device such as an atomic bomb uses a small. Conventional explosive to push subcritical masses of fissionable material into a supercritical mass. Fission occurs most instantaneously in the supercritical mass, and tremendous energy is released in a violent explosion 9. curie – Activity of a radioactive source is a measure of the number of nuclear disintegrations per unit of time. The unit of activity at the source is called a curie (Ci) which is defined 3.70*10^10 nuclear disintegrations per second. Activities are expressed in terms of fractions of curies.
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This note was uploaded on 02/09/2011 for the course PSC 1121 taught by Professor Tulsian during the Spring '11 term at Daytona State College.

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Chapter 13 Nuclear Reactions: Notes - Chapter 13 Nuclear...

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