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Quia – PARTS OF NUCLEAR REACTOR – Vocab from game SAT REVIEW BOOK: P. 336 Methods of Detection P. 335 Nature of Radioactive Emissions Writing Nuclear Equations Solving Half Life problems Differentiating between Decay, fission and fusion Benefits and Harm of using Radioactive Isotopes.

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  1. Quia – PARTS OF NUCLEAR REACTOR – Vocabfrom game SAT REVIEW BOOK: P. 336 Methods of Detection P. 335 Nature of Radioactive Emissions Writing Nuclear Equations Solving Half Life problems Differentiating between Decay, fission and fusion Benefits and Harm of using Radioactive Isotopes what you are responsible for

  2. Nuclear Chemistry is the study of reactions which alter the NUCLEUS of an atom. Reactions involving changes to the nucleus also involve Radioactivity: spontaneous emission of particles and/or energy from the nucleus of an atom Emissions are referred to as radiation. NuClear chemistry Overview

  3. NATURALLY and ARTIFICIALLY 1)Natural Transmutation – Alpha, Beta and Positron Decay - also FUSION Isotopes of elements that have unstable nuclei, (a ratio of neutron to protons that causes instability), will undergo decay. This causes them to be transformed into another element. The time it takes for half a sample of this isotope to decay and be transformed into another element is called half life. Nuclear reactions happen in two ways

  4. Fusion as natural transmutation: In stars, the nuclear reaction fusion results in the combination of lighter nuclei to form larger elements. In most cases fusion cannot occur on earth, the temperature and pressures required are too extreme to allow for fusion without it becoming too destructive. Nuclear reactions happen in two ways

  5. If # of neutrons is too high or too low, the nucleus becomes unstable and emits energy. Above atomic #83 there are no stable nuclides. Unstable Atoms

  6. A isotope undergoes transmutation when it decays. So the portion of the sample that has decayed, will turn into another element. If a sample of N-16 will decay to produce another gas. If the half life of N-16 is 7.13s, and there are 45 grams present, what other element will be present after decay occurs for 35.65 seconds? How much of it will be present? What happens to elements when they decay??

  7. Each particle leaves the nucleus, traveling through other materials. This is radiation. YOU MUST KNOW, the penetrating power of different particles. Some reactions generate gamma radiation- this is a very high energy emission with no mass or charge. As a result it has the greatest penetrating power. Particle emission & Energy

  8. Penetrating Power THESE ARE IN YOUR REGENTS and SAT REVIEW BOOKS

  9. 2) Artificial Transmutation- Fission and Nuclear Bombardment These are manmade reactions in which the nucleus of an atom is forced to collide with a smaller particle. Nuclear reactions happen in two ways

  10. Types of nuclear equations which include: Alpha decay, beta decay and positron decay Fission Fusion We started with

  11. Particles given off by reactions are somewhat similar to subatomic particles or elements you already know. Alpha particles = the nucleus of a helium atom. Since they have 2 protons and NO electrons, they have a net positive charge of +2 What about emissions?

  12. Beta Particles – Are high energy electrons ejected from the nucleus when a neutron decays into a proton. They have negligible mass and a charge of -1. Positrons – An anti-particle, basically the opposite of a beta particle. It also has negligible mass but the opposite +1 charge. Neutrons can be emitted by reactions, neutron notation will show it has a mass of 1, and the zero subscript, shows it is alone and has no protons. What about emissions?

  13. Gamma Radiation- when gamma radiation is emitted, it does not necessarily mean that transmutation has occurred. It does often occur after natural decay. It may also accompany fission and fusion reactions. It has no charge and no mass, so balance accordingly. What about emissions?

  14. Balancing Nuclear Reactions • In the reactants and products • Atomic numbers must balance • and • Mass numbers must balance • and • Charge Must Balance • Use a particle or isotope to fill in the missing protons and neutrons

  15. Alpha decay:mass decreases by four, atomic number decreases by two. 238U undergoes alpha decay 238U 4He + 234Th The total mass on the left must equal the total mass on the right (238 = 4 + 234) The total charge on the left must equal the total charge on the right (92 = 2 + 90) 92 2 90

  16. 240 4 Pu + He 94 2 Alpha decay 236 U 92

  17. Beta (minus) decay:mass remains the same, atomic number increases by one. 234Th undergoes beta decay 234Th 0e + 234Pa The total mass on the left must equal the total mass on the right (234 = 0 + 234) The total charge on the left must equal the total charge on the right (90 = -1 + 91) 90 -1 91

  18. 1 137 0 0 n Cs + e + e 0 55 -1 -1 Beta decay 137 Ba 56 1 p 1 (One of Cs’s neutrons converts to a proton and electron.)

  19. Positron (beta plus) decay:mass remains the same, atomic number decreases by one. 37K undergoes positron decay 37K 0e + 37Ar The total of the mass numbers on the left must equal the total on the right (37 = 0 + 37) The total charge on the left must equal the total charge on the right (19 = 1 + 18) +1 19 18

  20. 0 53 Fe + e 26 +1 Positron decay 53 Mn 25

  21. Fission converts a larger element into several atoms of elements with smaller atomic numbers. Therefore, this is a form of TRANSMUTATION, however, since it is initiated by people…IT IS ARTIFICIAL TRANSMUTATION Fission & Transmutation

  22. Fission Reactions: A Large nuclei will be shown, colliding with/absorbing a neutron or small particle. The product will be several smaller elements and emissions. Nuclear Bombardment, a smaller particle is shown colliding with an element. Fusion Reactions: Smaller elements, (such as hydrogen), will be shown combining to form larger elements. Other particles and emissions may be present. Pattern

  23. Complete the fission equation and account for the missing particle: Use table O for help with particle symbols Fission Practice 3

  24. Complete the following equation by finding the missing particle. 3H + 2 H  + 1 n Fusion Practice 4 He 1 1 2 0

  25. The half-life of a radioactive nuclide is the amount of time it takes for half of that nuclide to decay into a stable nuclide. The half-life of a radioactive nuclide cannot be changed.

  26. The principle behind half life allows radioactive isotopes to be used to: 1) Determine the age of organic and inorganic material. 2) Use selected isotopes for medical treatment and imaging Half Life

  27. If a sample of Radon – 222 is allowed to decay for 15.28 days… If the amount left is 5 grams, how much was present in the original sample? How many half lives did the sample undergo? Problem

  28. How much of a 20.g sample of 131I remains unchanged after 24 days? Problem

  29. What is the half life of an isotope that has decayed for 120 hours, if the original sample was 40 grams and the sample left weighs 1.25 grams. Problem

  30. Atomic Number & Symbol Mass Number “Heavy” atoms (greater than Bismuth, #83) naturally decay to smaller atoms along a consistent path, or series, of decays. Disintegration Series Radioactive U-238→ Th-234 + a Th-234 → Pa-234 + b Pa-234→ U-234 + b U-234→ Th-230 + a Th-230 → Ra-226 + a Ra-226 → Rn-222 + a Rn-222 → Po-218 + a Po-218 → Pb-214 + a Pb-214 → Bi-214 + b Bi-214 → Po-214 + b Po-214 → Pb-210 + a Pb-210 → Bi-210 + b Bi-210→ Po-210 + b Po-210 → Stable Pb-206 + a Source: http://www.frontiernet.net/~jlkeefer/uranium.html

  31. Energy released during nuclear reactions is much greater than the energy released during chemicalreactions. Fission – used in nuclear reactors and atomic bombs Fusion – used in hydrogen bombs and the energy that powers the sun.

  32. Energy released in a nuclear reaction (fission or fusion) comes from the fractional amount of mass converted into energy. Nuclear changes convert matter into energy. E=mc2 The energy released is equal to the mass lost (m) times the speed of light (c) squared. A small amount of mass lost converts to a very large amount of energy.

  33. Nuclear Fission Fission: process in which the nucleus of a large, radioactive atom splits into 2 or more smaller nuclei Caused by a collision with an energetic neutron. 1 1 235 139 94 n + Ba + Kr + 3 n + energy U 0 0 92 56 36 • *A neutron is absorbed by a U-235 nucleus. The nucleus is now less stable than before. It then splits into 2 parts and energy is released. Several neutrons are also produced; they may go on to strike the nuclei of other atoms causing further fissions in a process calledsupercriticality.

  34. *The process of neutron capture and nucleus splitting happens very quickly (takes about 1 x 10-12 seconds). An incredible amount of energy is released: As heat and gamma radiation Because the product atoms and neutrons weigh less than the original U-235 atom; the “missing mass“ has been converted to energy by E=mc2

  35. *A Fission Chain Reaction

  36. Why are neutrons used in this process and not protons? Question??? Since neutrons are not charged, they can approach the nucleus. Using a proton would mean having to overcome the repulsive force of the other positive protons present in the nuclei. Additionally, Particle accelerators often manipulate protons and electrons using enormous magnets. Due to a neutrons lack of charge, this is not possible.

  37. Basic Tour of a Nuclear Power Plant

  38. The reactor contains what are known as fuel rods. Fuel rods contain about 3% of the isotope U-235, (Uranium). The Fission reaction, is a chain reaction. The reactor employs what are known as Control Rods to help slow the reaction down if necessary. Control Rods are made of Boron and Cadmium, (other elements) and these absorb some of the neutrons. The Reactor

  39. The reaction produces a lot of heat, and water is circulated around it to transfer that heat to a place where it can produce steam. Water that Circulates around the reactor is heated to temperatures of 320 degrees Celsius That is a temp of 608 degrees Fahrenheit. Water Boils at 212 degrees Fahrenheit. www.howstuffworks.com

  40. This super heated water is piped through a separate tank where the heat transfers to water that is heated to produce steam. The steam produced then turns the turbine of an electrical generator. Producing Steam

  41. www.HowStuffWorks.com

  42. www.HowStuffWorks.com

  43. These structures we all associate with Nuclear Power Plants are actually the cooling towers. They help cool water down so it can either be re-circulated into the system, or moved to cooling reservoirs to be returned to a body of water.

  44. If technicians are able to drop the control rods into the reactor, they can stop the fission reaction… However a meltdown can still occur since so much heat collects in the reactor. This is also a reason why shutting a reactor down, even for temporary service, is a tricky maneuver.

  45. The United States currently imports over 58% of its oil supply. There is a need to develop alternative energy sources, such as nuclear, wind, geothermal, solar, … • By 2020 it is expected to be 67%. • At present about 20% of the electrical energy used in the U.S. is generated from power plants using uranium. In France the percentage is 75% . Nuclear Power

  46. Uses an unregulated fission reaction in a very fast chain reaction that releases a tremendous amount of energy. *Critical mass: the minimum amount of radioactive, fissionable material needed to create a sustainable fission chain reaction * Site of fission reaches temperatures believed to be about 10,000,000°C. • Produces shock waves and a, b, g, x-rays, and UV radiation. The Atomic Bomb

  47. *The classic “mushroom cloud” is a result of dust and debris lifted into the air as a result of the detonation. *US Army aerial photograph from 80 km away, taken about 1 hour after detonation over Nagasaki, Japan, August 9, 1945.

  48. 1 0 4 n + energy He + 2 3 2 H + H 1 1 Fusion: process in which 2 nuclei of small elements are united to form one heavier nucleus • * Requires temperatures on the order of tens of millions of degrees for initiation. • * The mass difference between the small atoms and the heavier product atom is liberated in the form of energy. • Responsible for the tremendous energy output of stars (like our sun) and the devastating power of the hydrogen bomb. Nuclear Fusion

  49. The first thermonuclear bomb was exploded in 1952 in the Marshall islands by the United States; the second was exploded by Russia (then the USSR) in 1953. “H bombs” utilize a fission bomb to ignite a fusion reaction. Stars & the Hydrogen Bomb

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