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Nuclear Chemistry
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Natural Radioactivity The spontaneous breakdown of atomic nuclei, accompanied by the release of some form of radiation
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Transmutation: the conversion of one element to another by means of a nuclear change To detect Radioactivity one could use Geiger Counter
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Types of Radioactive Emissions All differ in mass, size and charge Reference Table O
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Alpha Particle: 4 2 positive 2 charge helium nucleus mass of 4amu Ex: 226 88 Ra 222 86 Rn + 4 2 He
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Beta Particle: 0 -1 negative charge acts like a high speed electron no mass Example: 235 92 U 235 93 Np + 0 -1
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Gamma Radiation (NOT a Particle) no charge acts like a high speed x-ray but with a lot more energy no mass
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Positron Particle: 0 +1 positive 1 charge acts like positive electrons no mass
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ParticleSymbolMassCharge Relative Penetrating Power Alpha 4242 4amu+2Low Beta 0 -1 0Moderate Gamma 0000 00High Positron 0 +1 0+1Moderate
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Separation of Radioactive emissions by charge: Positively Charged Plate Negatively Charged Plate + -
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Half-Life The time it takes for half of the atoms in a given sample of an element to decay. Some selected half-lives are found on Table N All reactions on Table N are Natural Transmutation Formulas for half-life reactions are found on Table T
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Artificial Radioactivity Artificial Transmutation: artificial radioactivity produced by bombarding the nuclei of stable atoms with high energy particles, thereby producing radioactive atoms
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Fission Reactions The splitting of an atomic nucleus into two smaller nuclei by bombardment of a neutron (Nuclear Bomb). *Nuclear Reactors are fission reactors. Example: 235 92 U + 1 0 n 142 56 Ba + 191 36 Kr + 3( 1 0 n) + Energy
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Fusion Reactions A nuclear reaction in which two or more light nuclei combine to form a single nucleus. Requires huge amounts of pressure and extremely high temperatures. Produces much more energy than fission. Occurs naturally on the sun. (H- bomb) Example: 2 1 H + 2 1 H 4 2 He + Energy
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Uses of Radioactive Isotopes Lab: To trace chemical reactions. Industry: Radiating food to preserve by killing bacteria, mold, insect eggs.
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Medicine Must have relatively short half- lives and be quickly eliminated from the body. I-131 diagnosing and treating Thyroid conditions (half-life 8.07 days)
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Co-60 emits large amounts of gamma radiation as it decays, these rays can be aimed at cancerous tumors (half-life 5.26 years)
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Ra-226 used in treatment of certain cancers (half-life 1600 years) Tc-99 used in diagnosis of brain tumors (half-life 2.13x105 years
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Geology Fossils C-14 to C-12 ratio (while alive they are in equal amounts, once an organism dies C-14 is no longer taken in).
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Rocks U-238 to Pb-206 ratio (U-238 decays through a series of steps until it forms stable Pb-206. As time passes, the amount of U-238 decreases while the amount of Pb-206 increases).
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Balancing Nuclear Equations Steps for Balancing: Due to the Law of the Conservation of Matter, whatever is on the left side of the equation must also be on the right side of the equation.
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Add the mass numbers on the left side of the equation, this MUST equal the total mass numbers of the right side of the equation.
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Add the atomic numbers on the left side of the equation, this MUST equal the total atomic numbers on the right side of the equation. Example: 32 16 S + 1 0 n 1 1 H + 32 15 P
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