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Nuclear chemistry
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Subatomic Particles Protons- plus charge In the nucleus
Neutrons- neutral Electrons - negative charge Outside the nucleus
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http://www. teachersdomain
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Stability of Nuclei Ratio of neutrons to protons determines stability = “belt of stability” Ratio of nuclei with atomic numbers greater than 83 makes those nuclei unstable (radioactive, radioisotope) Unstable nucleus decays forming products that are more stable; emits radiation
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Radiation Radiation comes from the nucleus of an atom.
Unstable nucleus emits a particle or energy alpha gamma beta
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Types of Radiation 2+ 1- 1+ Alpha particle () Beta particle (-)
helium nucleus paper 2+ Beta particle (-) electron 1- lead Positron (+) positron 1+ concrete Gamma () high-energy photon
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Alpha Emission Numbers must balance!! daughter nuclide parent nuclide
particle Numbers must balance!!
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Beta Emission Numbers must balance!! parent daughter electron nuclide
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Positron Emission Numbers must balance!! parent daughter positron
nuclide daughter nuclide positron Numbers must balance!!
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Balancing Nuclear Equations
1) Use Table N to determine decay mode 2) In the reactants and products… Atomic and mass numbers must balance 3) A new element will be formed… according to the new atomic number
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DECAY MODE
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Learning Check 1 What forms when carbon -14 decays?
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Solution 1 What forms when carbon -14 decays? 14C 0 + 14 N 6 -1 7
Worksheet: Balancing nuclear equations
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Half-Life of a Radioisotope
The time for the radiation level to fall (decay) to one-half its initial value decay curve 8 mg 4 mg 2 mg mg initial 1 half-life 2 3
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Examples of Half-Life Isotope Half life C-15 2.4 sec Ra-224 3.6 days
I days C years U years
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HALF- LIFE
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Learning Check 2 ½ life amount time
How many half lives will it take for 50 grams of 99 Tc to decay to 6.25 g? ½ life amount time
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Solution 2 How many half lives will it take for 50 grams of 99 Tc to decay to 6.25 g? 3 half lives ½ life amount time x 105 (2.13 x 105) (2.13 x 105)
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½ life amount time
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Transmutation Natural Artificial One element becomes another. Alpha
Beta Gamma Positron Artificial Fission Fusion
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Nuclear Fission Fission
larger unstable nuclei break up into smaller more stable nuclei; release of neutrons causes a chain reaction and energy release 235U n Ba Kr + 3 1n + Energy
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Fission
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Nuclear Power Fission Reactors Cooling Tower
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Nuclear Power Fission Reactors
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Nuclear Fusion Fusion small nuclei combine 2H + 3H 4He + 1n + 1 1 2 0
Occurs in the sun and other stars, hydrogen bomb Energy
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Nuclear Power Fusion Reactors (not yet sustainable)
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Nuclear Power Fusion Reactors (not yet sustainable)
National Spherical Torus Experiment Tokamak Fusion Test Reactor Princeton University
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Fission vs. Fusion 235U is limited fuel is abundant danger of meltdown
toxic waste thermal pollution fuel is abundant no danger of meltdown no toxic waste not yet sustainable
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Nuclear Weapons Atomic Bomb
chemical explosion is used to form a critical mass of 235U or 239Pu fission develops into an uncontrolled chain reaction Hydrogen Bomb chemical explosion fission fusion fusion increases the fission rate more powerful than the atomic bomb
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Learning Check 3 Indicate if each of the following are
Fission (2) fusion Nucleus splits Large amounts of energy released Small nuclei form larger nuclei Hydrogen nuclei react Energy
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Solution 3 Indicate if each of the following are Fission (2) fusion
Nucleus splits Large amounts of energy released Small nuclei form larger nuclei Hydrogen nuclei react
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Nuclear Chemistry Uses
Dating dating previously living materials (Carbon-14) dating rocks and other geological formations (Uranium-238)
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Nuclear Chemistry Uses
Radiation treatment using -rays from cobalt-60. Medical Application Radiation Treatment larger doses are used to kill cancerous cells in targeted organs (Cobalt-60) Radioisotope Tracers (absorbed by specific organs and used to diagnose diseases) Iodine-131 detection and treatment of thyroid conditions Technetium-99 detects presence of tumors
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Nuclear Chemistry Uses
Food Irradiation radiation is used to kill bacteria (Co-60 and Cs-137) Consumer Products ionizing smoke detectors - 241Am
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Nuclear Chemistry Uses
Radioactive Tracers (tracers follow the path of a material in a system) Map the path of carbon in metabolic processes (Carbon-14) study plant growth, photosynthesis (Phosphorus-31)
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Nuclear power plant.
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Diagram for the tentative plan for deep underground isolation of nuclear waste.
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