A Bombs. Student Number Period

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1 Student Number Period A Bombs How many times did I say it, Harold? How many times? Make sure that bomb shelter s got a "How can opener many times ain t much did I say good it, without Harold? a can How opener, many times? I said. 'Make sure that bomb shelter's got a can opener ain't much good without a can open,' I said."

2 Unit Objectives 1. DESIGN, CONDUCT and EVALUATE an experiment on the effects of shielding on radiation. 2. DESIGN, CONDUCT and EVALUATE an experiment on the effects of distance on radiation. 3. IDENTIFY and DIFFERENTIATE between alpha, beta and gamma radiation and their effects. 4. Give EXAMPLES of background radiation and other radiation sources. 5. COMPUTE the rate of radioactive decay and half lives. 6. DESCRIBE other uses of radiation besides bombs and reactors. 7. INTER CONVERT moles, grams and Avogadro s number. A...Bombs Packet Page 2

3 What is RADIATION? Radiation is the process of atoms and molecules energy sending out waves or particle in all directions radiation is like and is generated inside matter when change position in atoms or when atoms change positions in molecules. Examples of electromagnetic radiation are radio waves, radar, microwaves, infrared waves (heat radiation), (colors), ultraviolet waves (black light), x rays. In radiation the of an atom changes. The nucleus changes because something makes it. When this happens the nucleus gets rid of particles and/or energy Some radiation has such energy that it can knock out of atoms and molecules. It is called ionizing. An ion is a charged atom or molecule. Ionizing radiation produces charged ions. There are main types of ionizing radiation. 1. Fast Moving sub atomic. a. Alpha particles are composed of two and two. They are identical to nuclei. They are charged and have an atomic mass of. The atomic number by two and the mass number by four. They are symbolized as : α or 4 He 2 Sg Rf He 2 4 A...Bombs Packet Page 3

4 b. particles are high speed electrons created in and expelled from the nucleus. These particles come from the decay of a n > p + β These particles have a charge and have a mass close to an. The atomic number by one and the mass number stays the. 14 C N 7 7 e c. particles are created in and expelled from the nucleus. These particles come from the decay of a p > n + β These particles have a charge and have a mass close to an. The atomic number by one and the mass number stays the. d. Electron An orbital electron is captured by the nucleus of its own atom. The electron combines with a proton and a is formed. The atomic number by one and the mass number stays the. 2. High energy radiation. a. X rays X rays come from an X ray gun. In the gun, high speed are targeted at some element like copper or molybdenum. The electrons abruptly when they hit the target atoms. The kinetic energy they lose in the stopping process is turned into X rays. b. Gamma rays A form of electromagnetic radiation given off by the in a decay process. A gamma ray has mass. A...Bombs Packet Page 4

5 e. Cosmic rays They are really energetic. The particles come from space, particularly the and solar flares. They are mainly. These energetic particles with other atmospheric particles causing them to ionize and/or disintegrate. A Brief Understanding of Subatomic Particles and Interactions Scientists use to track and identify each of the many particles produced in a single collision of high energy particles. A...Bombs Packet Page 5

6 Particles 1. Quarks There are types of quarks. They are never found, only inside protons and neutrons. A has two up quarks and one down quark. A has two down quarks and one up quark. 2. Leptons The is the best known lepton. Leptons may be found by themselves. are leptons that have no electric charge and very little mass. 3. Antimatter For every type there is a corresponding antiparticle type. Particle and have identical and spin but opposite. When a particle and an antiparticle meet, they may, disappearing to give some other form of energy. A...Bombs Packet Page 6

7 Forces and interactions (What holds the atom together?) 1. Gravity Acts on all matter/particles effects very when dealing with subatomic particles. 2. Electromagnetic force Responsible for electrons to the nucleus. The associated carrier particle of the electromagnetic force is the and gamma ray (a photon from a nucleus transition). 3. Strong force Holds together to form protons and neutrons. A residual strong force interaction holds the together. The carrier particle is a (glues quarks together). 4. Weak Interactions Allows quarks and leptons to to another type of quark or lepton. Responsible for the fact that all quarks and leptons decay to produce lighter versions. The associated carrier particles are W and Z bosons. A...Bombs Packet Page 7

8 The CLOUD Chamber Purpose : To observe tracks made by ionizing radiation. Procedure : 1. View the cloud chamber through the top. You should see white lines or tracks inside the jar close to the bottom. You may be able to find three kinds of track: a. Most of the tracks will be about 1 cm long and quite sharp. These are made by alpha particles. b. Sometimes you will see longer, thinner, tracks. These are made by beta particles. c. Occasionally, you may see some twisting, circling tracks that are so faint that they are difficult to see. These are caused by gamma rays. Observations: 1. Draw and label a picture of the cloud chamber device. 2. Draw and label a picture of what you observed when looking down through the top of the cloud chamber. Conclusions: 1. Were you able to observe radiation directly or indirectly in the cloud chamber? 2. Write a concluding statement explaining how we know radiation exists. A...Bombs Packet Page 8

9 Penetrating Power Note: CPM = counts/minute, 0.1 mrem = 100 counts/minute Part A: Determine background radiation Procedure: With all radioactive sources far removed from the Geiger counter, determine the number of counts once a minute for three minutes. Record and average your results. Background radiation: 1 st One Minute count counts (Counts on radiation 2 nd One Minute count counts counter dial) 3 rd One Minute count counts Average Background: counts Part B: The effects of shielding on radiation Purpose: To observe the ability of alpha, beta and gamma rays to pass through different substances. Materials: Procedure: Radiation meter (Geiger counter), Meter ruler Poster paper, cardboard, aluminum, wood, and lead shields Alpha, beta and gamma radiation sources 1. Complete the experimental design table below. 2. Hold the radiation meter 10 cm from the radiation source. 3. Hold shields directly in front of radiation detection window. 4. Test each shield separately with each radiation source. Be sure to include one trial with no shielding for each radiation source. 5. Do one trial for four types of shielding on each type of radiation source. Design table: Problem: What type of particle has greatest ability to pass through different substances? Hypothesis: IV: Units: DV : C's: Units: A...Bombs Packet Page 9

10 6. Perform the experiment, collect and record your measurements in the data table. Make sure to subtract the average background radiation reading from each trial to get a true reading. Results data table: Type of Shielding Type of Radiation Alpha Beta Gamma No Shielding Part C: Effect of distance on radiation Purpose: To observe the effect of distance from a radiation source on the strength of the radiation. Materials: Radiation meter, gamma radiation source, meter stick Procedure: 1. Construct an experimental design table to collect radiation meter readings in as you move the gamma source away from the radiation meter in 10 cm increments. Design table: Problem: Hypothesis: IV: Units: DV : C's: Units: A...Bombs Packet Page 10

11 Results table: Make sure to subtract the average background radiation reading from each trial to get a true reading. Graph: Graph the effect of distance on radiation strength with the adjusted counts/minute on one axis and the distance from the source on the other axis. Conclusion: 1. What units does the radiation meter measure in? What does each click mean? 2. Summarize the effects of shielding on the different types of radiation. Gamma radiation: Beta radiation: Alpha radiation: 3. How are distance and the strength of radiation related? A...Bombs Packet Page 11

12 HALF LIFE!!! Radioactive materials become less radioactive over time as a result of a process known as radioactive decay. The rate of decay for a radioactive element is measured in terms of a characteristic time, the half life. This is the time it takes for half of an original quantity of the element to decay. For example, radium 226 has a half life of 1620 years. This means that half of a sample of radium will decay by the end of 1620 years. In the next 1620 years, half of the remaining radium will decay, leaving one fourth of the original amount of radium. Problem: How many mg of phosphorus 32 remain after 57.2 days if you start with 4.0 mg of the isotope? Phosphorus 32 has a half life of 14.3 days. Half of a life In this activity, you will simulate radioactive decay and plot the decay of an isotope of the imaginary element pennium. In this activity, you have 50 pennies. You and your partner should arrange all the pennies so they are tails up. You are to flip each of the pennies one at a time. Each penny that turns up heads has decayed, while the pennies that are tails are still radioactive. Each time, those pennies that have decayed are taken out. Count the number out and record the results as indicated on the chart. Then flip those that are stilled radioactive again. Continue until all the pennies have decayed, or you have completed six rounds of flipping. Plot the results on the graph below. Flip Number Number Number Decayed Radioactive Number of Radioactive Pennies Number of Flips (Half Lives) 8 A...Bombs Packet Page 12

13 Radioactive DECAY Many atoms have an imbalance of protons and neutrons in their nucleus. Other atoms just have too many protons in the nucleus to be stabilized by the neutrons (especially uranium and those elements with greater atomic numbers). Because of this, the nuclei of these atoms decay and emit alpha, beta and gamma rays to achieve a stable nucleus. Procedure: In this exercise you will trace the radioactive decay of uranium 235 as it becomes as series of new elements. Start with U 235 in the upper right hand corner of the diagram below. The table on the left lists the type of decay in each step of the process. Remember with the loss of an alpha particle the atomic number decreases by two and the atomic mass decreases by four. When a beta particle is lost the atomic number increases by one and the atomic mass stays the same. Using your periodic table, identify each element in the series by its chemical symbol. The first two steps have been completed for you. Step Particle Emitted Alpha Beta Alpha Alpha Beta Alpha Alpha Alpha Beta Alpha Beta Stable 235 U Th 231 Pa Atomic Mass Atomic Number A...Bombs Packet Page 13

14 Radiation in YOUR Life Ionizing radiation sources include both and man made sources. The of the exposure to the main natural sources is called. Natural Sources of Background Radiation Cosmic Radiation Originates outside the Earth s. Terrestrial Radiation The Earth s mantle contains many sources, such as. Radon and its Decay Products is one of the products of the radioactive of uranium. Radon is a and enters the Earth s. Radon can also become trapped inside because of ventilation in today s well insulated, energy houses. Food Sources Potassium and are present in the food we eat. They are important parts in our daily. There is a radioactive isotope of potassium (potassium 40) found in the. Plant roots this nutrient, and we eat the plants. Plants also take in the radioactive isotope of carbon ( ) through photosynthesis. Carbon 14 is produced by rays. A...Bombs Packet Page 14

15 Man Made Sources of Background Radiation Medical Sources Diagnostic X rays (dental and medical) products Smoke detectors (americium 241) Luminous signs and watches (radium ) Lantern mantles (thorium) Pottery and tile paints (uranium) TV and computer monitors from past nuclear testing Nuclear power generation Fuel, production and waste Normal operations Past accidents exposure Interaction with Natural Sources of Background Radiation travel oil and gas production By products of mineral processing A...Bombs Packet Page 15

16 Personal Radiation Dose We live in a radioactive world. Radiation is all around us as part of our natural environment. It is measured in terms of millirems (mrems). The annual average dose per person from all sources is about 360 mrems, but it is not uncommon for any of us to receive far more that that in a given year (usually due to medical procedures). For those who work with nuclear materials the international standards allow up to 5,000 mrems per year exposure. Fill in the answers below based on your activities during the past year. WHERE YOU LIVE Cosmic radiation at sea level (from outer space) For your elevation (in feet) : add 3 mrems for every 1000 feet. Terrestrial (from ground) If you live in a state the borders the Gulf or Atlantic, add 23 If you live in the Colorado Plateau Area, add 90 If you live in Middle America or the Far West, add 46 House construction: If you live in a stone, brick, or concrete building, add 7.. WHAT YOU EAT AND DRINK Internal radiation (in your body) From food and water : U.S. average From air (radon) : U.S. average.. HOW YOU LIVE Transport of radioactive material Low level radioactive waste burial sites Consumer products and sources such as radon from water and radiation from tobacco smoke. Weapons test fallout (less than 1).. Jet plane travel For each 1000 miles you travel, add 1 If you have porcelain crowns or false teeth, add If you use gas lantern mantles when camping, add If you wear a luminous wristwatch (LCD), add If you luggage inspection at airports (X ray machine), add If you use a computer terminal (more than 1 hour/day), add 1... TV viewing : For each hour per day, add x 0.15 = If you have a smoke detector, add If you wear a plutonium powered cardiac pacemaker, add 100. If you have had medical exposures: Chest x rays, add 10 per visit.. Gastrointestinal tract x ray, add 200 per visit. Dental x rays, add 10 per visit.. Nuclear medical procedures (U.S. average), add 14 If you live within 50 miles of a nuclear power plant, nuclear laboratory, or a university with a nuclear power reactor, add If you live within 50 miles of a coal fired electrical utility plant, add If you smoke, add 1300 Add the score to get your total. TOTAL A...Bombs Packet Page 16

17 Radiation uses Ionizing radiation is harmful to human health in large doses. However, both ionizing and non ionizing radiation has many uses in our lives. Below are some examples. Ionizing Radiation Uses: A. X rays are used by and dentists to view underlying structures such as bones. also use X rays to prevent hijacking and terrorist attacks by scanning. B. Iodine 131 is used to treat problems, such as cancer. To treat cancers, radiation sources must be so they do not kill too many healthy cells. C. Phosphorous 32 is used to study plant and animal. The P 32 replaces phosphorous in such molecules as ATP and DNA. D. Plutonium 239 is used in the construction of pacemaker because they only have to be changed once every 10 years. E. Americium 241 is used in detectors in homes and businesses. F. Archeologists use carbon 14 decay rates to calculate the of once living tissue. When a living organism it has the same carbon 14 concentration as background levels. After the organism dies, the carbon 14 begins to decay. By calculating the number of that have occurred, scientists can calculate how long ago the organism died. G. is also being used to treat food and prevent it from. Much controversy still remains about this use. Non Ionizing Radiation Uses Microwave ovens, need we say more?! A...Bombs Packet Page 17

18 A Bomb Practice Match the statements on the left with the terms on the right. Place the letter of the term in the blank in front of the question number. A term may be used once, more than once or not at all. 1. Causes the atomic number to decrease by two 2. A negatively charged particle with a mass of an electron 3. Electro magnetic energy given off by nucleus 4. Particle comes from the changing of a proton to a neutron 5. Causes the atomic number to increase by one 6. Positively charged particle with an atomic mass of 4 7. The particle given off when 212 Tl 81 decays into 212 Pb Causes the atomic number to decrease by one 9. An energetic particle from the sun 10. High speed electrons created in / expelled from the nucleus 11. The particle given off when 218 At 85 decays into 214 Bi Composed to two protons and two neutrons 13. A positively charged particle with a mass of an electron 14. Causes the atomic mass to decrease by The particle given off when 49 Cr 24 decays into 49 V 23 a. Alpha particle b. Beta particle c. Cosmic radiation d. Gamma rays e. Positron particle Complete the following concept map about nuclear radiation by using the terms to the right. Draw lines to connect the boxes to show the relationship between terms. Alpha particles Beta particles Nuclear Radiation Cosmic radiation Fast moving particles Gamma rays High energy radiation Positron particles X rays PARTICLE DECAY PROBLEMS: Alpha radiation is emitted during the disintegration of the following isotopes. Write balanced nuclear equations for their decay processes and name the element produced in each case. 24. Uranium 238 ( 238 U 92 ) 25. Thorium 230 ( 230 Th 90 ) 26. Radon 222 ( 222 Rn 86 ) A...Bombs Packet Page 18

19 The following radioisotopes are beta emitters. Write balanced nuclear equations for their decay processes. 27. Carbon 14 ( 14 C 6 ) 28. Potassium 40 ( 40 K 19 ) 29. Strontium 90 ( 90 Sr 38 ) Complete these nuclear reactions P e Nb e Tl Au U He 2 How are the atomic number and atomic mass of a nucleus affected by loss of the following emissions. 34. Alpha Particle 35. Beta Particle 36. Gamma Ray Complete and balance the following nuclear equations. In several cases you will need to determine if an alpha or beta particle is one of the products. 37. Copper 66 decays to produce the isotope zinc Nitrogen 14 is bombarded with an alpha particle to produce an isotope of fluorine 39. Radon 217 decays into polonium An unknown isotope of thorium decays into protactinium 234 plus a beta particle HALF LIFE PROBLEMS : 41. Manganese 56 is a beta emitter with a half life of 2.6 hours. What is the mass of manganese 56 in a 23 gram sample of the isotope after 13 hours? Radon 226 emits alpha radiation and has a half life of 3.8 days. Assume a starting mass of 16 grams of Rn How long is four half lives? 43. How many grams of Rn 226 will still exist after three half lives? 44. The mass of cobalt 60 in a sample is found to have decreased from 0.8 g to 0.2 g in a period of 10.5 years. From this information, calculate the half life of cobalt 60. A...Bombs Packet Page 19

20 45. A patient is administered 20 mg of iodine 131. How much of this isotope will remain in the body after 40 days if the half life of iodine 131 is 8 days? 46. Explain the term half life. 47. Suppose an archeologist extracts 10 grams of carbon from an ancient ax handle and finds that carbon to be one quarter as radioactive as 10 grams of carbon extracted from a freshly cut tree branch. The half life of carbon 14 is 5,713 years. About how old is the ax handle? Amount of Radioactive Substance (grams) Radioactive Decay 0 days 10.5 days 21 days 31.5 days 42 days 53.5 days 48. Using the graph to the left, what is the half life of the radioactive substance? 49. How many grams are present on day 21? 50. On what day would 20 grams of radioactive substance be present? Time (days) Solve the following challenges using a PICKET FENCE. 51. What percentage of C 14 would you expect a 2 kg piece of 34,000 year old fossilized bone from a mastodon to have when compared to a similar piece of bone from a modern elephant? The half life of C 14 is 5715 years? The Environmental Protection Agency and health officials are concerned about the levels of radon gas in homes. 52. If a sample of gas taken from a basement contains 2.38 micrograms of radon 222, how many atoms were in the sample? (1 microgram = 1 x 10^6 grams) 63. Assume the half life of radon 222 is 3.8 days, how much radon will remain in the gas after 19 days? A...Bombs Packet Page 20