Nuclear Physics and Radioactivity Vocabulary

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proton
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the nucleus of the simplest atom- hydrogen. It has a positive charge of +q and a mass of m=1.67×10^-27 kg
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neutron
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a particle found in the nucleus that is electrically neutral and that has a mass almost identical to the proton. It was discovered in 1932 by James Chadwick, Its charge is q=0, its mass is m=1.6749×10^-27 kg, (Chadwick’s discovery established that the nucleus contained two types of particles)
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nucleons
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term that refers to the two constituent particles of a nucleus
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atomic number
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the number of protons in a nucleus (designated by the letter Z)
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atomic binding energy
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the total number of protons and neutrons (designated by the letter A)
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nucleon
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the mass of a nucleus is very close to Z times the mass of one ___
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isotope
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nuclei that contain the same number of protons but different numbers of neutrons; are generally described as “element-#”
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mass defect
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th difference in the mass of a nucleus and the sum of the masses of its constituent particles
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nuclear binding energy
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the amount of energy that must be put into a nucleus to break it into its constituent particles; it is the energy equivalent of the mass defect found by using E=mc^2.
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strong nuclear force
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an attractive force that acts between all nucleons; protons attract each other via this force while they repel each other via the electric force.
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radioactive
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nuclei that decay, emitting radiation, are considered to be this. in other words a nucleus that is coming apart is doing this. a new element is produced
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transmutation
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the changing of one element into another element via radioactive decay.
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~conservation of energy ~conservation of electric charge ~conservation of mass
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when unstable nuclei disintegrate, they must obey what three laws of physics?
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alpha particle
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has a charge of q=+2 and a mass of A=4, when this is emitted the number of protons is reduced by two and its mass is reduced by four. these are emitted by very large nuclei where the strong nuclear force is insufficient to hold the nuclei together
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helium
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an alpha particle is essentially a ___ nucleus
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beta particle
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a negative electron emitted from he nucleus that came from a broken down neuron. are emitted by nuclei that have too many neutrons relative to the number of protons
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weak nuclear force
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involved in the production of a beta particle in the nucleus
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gamma radiation
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is composed of high energy photons, has no charge and no mass
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positron
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a positive electron produced in the nucleus by the decay of a proton into a positron and a neuron. it has a charge of q=+1 and essentially no mass. there are emitted by nuclei that have too few neutrons relative to their number of protons
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protron
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the nucleus of a hydrogen atom. they symbol is p
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proportionality
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the decay constant is a constant of ____
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half life
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the time it takes for half he original amount of a substance to decay
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mass-energy equivalence
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one of the most profound results of Einstein’s theory of relativity was the fact that mass could be converted into energy and vice versa. (E=mc^2)
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fission
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a division of a nucleus into two or more smaller daughter nuclei.
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chain reaction
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neutrons produced by the fission of one nucleus induce the fission of there nuclei
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critical mass
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he minimum mass of uranium needed to produce a self-susaining chain reaction
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fusion
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two or more nuclei combine to form a larger nucleus. (sun)
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artificial transmutation
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process of using nuclear reactions to change the atomic number of the nucleus by changing one element into another
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moderator
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slows down neutrons produced in chain reactions so the can be more easily absorbed by other nuclei so fission continues
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control rods
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absorb neutrons, controlling the rate of reaction
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breeder reactors
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ones in which some of the neutrons produced in the fission of uranium produce plutonium. this plutonium can be used in an atomic bomb.

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