Chapter 5 Notes - Nuclear Chemistry PDF

‫)‪Chapter (5‬‬ ‫‪Nuclear Chemistry‬‬ ‫‪5.1 Natural Radioactivity‬‬ ‫َّ َّ‬ ‫َ‬ ‫البوتونات ذات الشحنات الموجبة بشدة‪ ،‬إَّل أنه‬ ‫تحتوي نواة الذرة عىل بروتونات ونيوترونات‪.‬داخل النواة تتنافر ر‬ ‫َّ‬...

‫)‪Chapter (5‬‬ ‫‪Nuclear Chemistry‬‬ ‫‪5.1 Natural Radioactivity‬‬ ‫َّ َّ‬ ‫َ‬ ‫البوتونات ذات الشحنات الموجبة بشدة‪ ،‬إَّل أنه‬ ‫تحتوي نواة الذرة عىل بروتونات ونيوترونات‪.‬داخل النواة تتنافر ر‬ ‫َّ‬ ‫َ ُ‬ ‫ً‬ ‫ُ َ‬ ‫مستقرة عندما‬ ‫الت تحدث ربي الجسيمات النووية‪.‬وتكون النواة‬‫القصبة المدى ي‬ ‫ر‬ ‫يوجد أيضا العديد من قوى التجاذب‬ ‫أكب من قوى التنافر مما يؤدي إىل ترابط مكونات النواة لهذا السبب تكون هذه النواة مستقرة (‬ ‫تكون قوى التجاذب ر‬ ‫َّ‬ ‫مستقرة ( نواة مشعة )‪.‬‬ ‫غب‬ ‫غب مشعة )‪.‬و لكن عندما تكون قوى التنافر أقوى من قوى التجاذب تصبح النواة ر‬‫ر‬ ‫َّ‬ ‫مؤينة‪ ،‬مثل َّ‬ ‫قرة ( المشعة ) أن تصبح ر‬ ‫ُ‬ ‫أشعة جاما ‪ γ‬وجسيمات‬ ‫أكب استقر ًارا بإطالق إشعاعات‬ ‫غب المست َّ‬ ‫يمكن لألنوية ر‬ ‫المستقرة ‪. radioactive decay‬‬ ‫َّ‬ ‫غب‬ ‫ألفا ‪ ، α‬وجسيمات بيتا ‪ ،β‬و ُي َّ‬ ‫التلقائ لإلشعاع من النواة ر‬ ‫ي‬ ‫سّم االنبعاث‬ ‫َّ‬ ‫ُ‬ ‫وت َع ُّد المادة الت ُيمكن أن تخضع لالضمحالل ( التحلل ) الشعاي مادة ُم َّ‬ ‫شعة‪ ،‬ومقدار الشعاع المؤين الذي تبعثه‬ ‫ي‬ ‫ي‬ ‫الشعاي‪.‬‬ ‫ي‬ ‫المادة هو نشاطها‬ ‫‪A stable nucleus remains intact indefinitely, an unstable nucleus is‬‬ ‫‪radioactive, which means that it spontaneously emits small particles‬‬ ‫‪of energy called radiation to become more stable (the spontaneous‬‬ ‫‪disintegration of a nucleus by the emission of radiation). Radiation‬‬ ‫‪may take the form of alpha (α) and beta (β-) particles, positrons (β+),‬‬ ‫‪or pure energy such as gamma (γ) rays. An isotope of an element that‬‬ ‫‪emits radiation is called a radioisotope.‬‬ ‫النشاط الشعاي هو تفتت طبيع تلقائ تتحول خالله نواة مشعة غب مستقرة إىل نواة ُأخرى ر‬ ‫أكب استقرارا‬ ‫ر‬ ‫ي‬ ‫ي‬ ‫ي‬ ‫إعداد ‪ :‬محمود الحمد ‪51055849‬‬ ‫‪Page 1‬‬  - Most naturally occurring isotopes of elements up to atomic number 19 have stable nuclei. - Elements with atomic numbers 20 and higher usually have one or more isotopes that have unstable nuclei in which the nuclear forces cannot offset the repulsions between the protons. - An unstable nucleus is radioactive, which means that it spontaneously emits small particles of energy called radiation to become more stable. Radioisotopes has an unstable nucleus and emits radiation can be one or more isotopes of an element Includes the mass number in its name Carbon-14, a radioactive isotope of carbon that is used for archeological dating, has a mass number of 14 and an atomic number of 6. Stable and Radioactive Isotopes 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 2 Types of Radiation Emitted By emitting radiation, an unstable nucleus forms a more stable, lower energy nucleus. is identical to a helium nucleus has 2 protons and 2 neutrons has a mass number of 4 has a charge of 2+ has a low energy compared to other radiation particles is a high-energy electron has a mass number of 0 and a charge of 1− forms in an unstable nucleus when a neutron changes into a proton and an electron 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 3  has a mass number of 0 and a charge of 1+ forms in an unstable nucleus when a proton changes into a neutron and a positron is high-energy radiation has a mass number of 0 and a charge of 0 is a form of energy emitted from an unstable nucleus to give a more stable, lower-energy nucleus 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 4 Radiation Protection Proper shielding is necessary to prevent exposure. Alpha particles, which have the largest mass and charge of the radiation particles, travel only a few centimeters in the air before they collide with air molecules, acquire electrons, and become helium atoms. A piece of paper, clothing, and our skin are protection against alpha particles. Beta particles have a very small mass and move much faster and farther than alpha particles, traveling as much as several meters through air. They can pass through paper and penetrate as far as 4 to 5 mm into body tissue. External exposure to beta particles can burn the surface of the skin, but they do not travel far enough to reach the internal organs. Heavy clothing such as lab coats and gloves are needed to protect the skin from beta particles. Gamma rays travel great distances through the air and pass through many materials, including body tissues. Because gamma rays penetrate so deeply, exposure to gamma rays can be extremely hazardous. Only very dense shielding, such as lead or concrete, will stop them. 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 5 ‫‪5.2 Nuclear Reactions‬‬ ‫‪Nuclear equations use atomic symbols to show the changes in nuclear‬‬ ‫‪reactions.‬‬ ‫وتعتب التفاعالت النووية مسئولة عن تكوين جميع‬ ‫َّ‬ ‫تتيب اأنوية الذرية من حالة إىل أخرى‪.‬‬ ‫يف التفاعالت النووية‪،‬‬ ‫ر‬ ‫ر‬ ‫ً‬ ‫الكببة يف الكون تقريبا‪ ،‬وتكوين الطاقة الشمسية يف باطن الشمس؛ حيث يرتفع الضيط والحرارة‪.‬يمكن‬ ‫الذرات‬ ‫ر‬ ‫استخدام التفاعالت النووية لتوليد الكهرباء يف مصانع توليد الطاقة النووية وتشخيص اأمراض يف المستشفيات‪.‬‬ ‫ُّ‬ ‫والتحول‪.‬‬ ‫هناك ثالثة أنواع مختلفة من التفاعالت النووية‪ :‬االنشطار واالندماج‬ ‫)‪(Radioactive Decay – Nuclear Fission – Nuclear Fusion‬‬ ‫إعداد ‪ :‬محمود الحمد ‪51055849‬‬ ‫‪Page 6‬‬  ‫ُّ‬ ‫التحول عن‬ ‫َّ‬ ‫تتحول ذرات عنرص ما إىل ذرات عنرص آخر ‪،‬‬ ‫ُّ‬ ‫التحول ‪ :‬هو أحد أنواع التفاعالت النووية؛ حيث‬ ‫‪-1‬‬ ‫غب المستقر أو‬ ‫النظب ر‬ ‫ر‬ ‫غب المستقرة‪.‬سيؤدي‬‫ف الطبيعة للنظائر ر‬ ‫الشعاي عملية تحدث‬ ‫طريق االضمحالل‬ ‫َّ‬ ‫ً‬ ‫َّ‬ ‫ًّ ي ُ‬ ‫ي‬ ‫نظب‬ ‫النظب إىل ر‬ ‫ر‬ ‫المشع إىل انبعاث جسيمات أو طاقة تلقائيا‪ ،‬تسّم إشعاعا؛ اأمر الذي يتسبب يف تحويل هذا‬ ‫ر‬ ‫أكب استقر ًارا‪.‬‬ ‫‪.‬‬ ‫ر َ‬ ‫الكثب من الطاقة‬ ‫ر‬ ‫أكب‪.‬ينتج عن االنشطار‬ ‫صيب رتي أو‬ ‫ر‬ ‫نواتي‬ ‫ر‬ ‫‪ -2‬يحدث االنشطار عندما تنقسم النواة الثقيلة إىل‬ ‫َ‬ ‫المستخدمة لتوليد الكهرباء داخل مصانع الطاقة النووية‪.‬‬ ‫‪ -3‬يحدث االندماج عندما تتحد نواتان خفيفتان أو ر‬ ‫أكب لتكوين نواة أثقل‪.‬التفاعل الذي يحدث يف الشمس‬ ‫الهيدروجي لتكوين الهليوم‪.‬‬ ‫ر‬ ‫والنجوم اأخرى هو تفاعل اندماج يبدأ بدمج نوى‬ ‫إعداد ‪ :‬محمود الحمد ‪51055849‬‬ ‫‪Page 7‬‬ Radioactive Decay An unstable nucleus spontaneously breaks down by emitting radiation ‫ عملية تلقائية يتحول فيها العنرص إىل عنرص اخر نتيجة فقد جسيمات‬: ‫االشعاي‬ ‫ي‬ ) ‫االنحالل ( التحلل أو الضمحالل‬ َّ.‫مستقرة‬ ‫غب‬ ‫التلقائ لإلشعاع من نواة ر‬ ‫الفا أو جسيمات بيتا وانطالق أشعة جاما وهو االنبعاث‬ ‫ي‬ The main factor that determine the nuclear Stability is the number of neutrons (N), the number of protons (Z), and their ratio (N/Z), Nuclear Equations When a nuclide decays, it forms a nuclide of lower energy, and the excess energy is carried off by the emitted radiation and the recoiling nucleus. The decaying, or reactant, nuclide is called the parent; the product nuclide is called the daughter. Radioactive nucleus → new nucleus + radiation (α, β, β+, γ) 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 8  :-‫أنواع التحلل اإلشعاعي‬ Alpha Decay - Involves the loss of an α particle from a nucleus. - For each α particle emitted by the parent, The mass number decreases by 4 and the atomic number decreases by 2 in the daughter. ‫ وهذا‬. ‫ونيوتروني وهو عبارة عن نواة ذرة الهيلوم‬ ‫ر‬ ‫بروتوني‬ ‫ر‬ ‫يف هذه العملية تفقد النواة المشعة جسيم الفا المكون من‬ ً ‫بوحدتي وبذلك تكون النواة الناتجة مختلفة تماما عن‬ ‫ر‬ ‫الكتىل بمقدار أرب ع وحدات والعدد الذري‬ ‫ي‬ ‫يعت نقصان العدد‬ ‫ي‬.‫النواة اأم‬ Writing an Equation for Alpha Decay 1- Write the balanced nuclear equation for the alpha decay of americium-241, used in smoke detectors. 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 9 ‫‪Beta Decay‬‬ ‫‪(Or negatron emission) occurs through the ejection of a β particle‬‬ ‫‪from the nucleus.‬‬ ‫‪A beta β particle is an electron emitted from the nucleus when a‬‬ ‫‪neutron in the nucleus breaks down to form a proton and a beta‬‬ ‫‪particle, increasing the atomic number by 1.‬‬ ‫وف‬ ‫الت تحقق االستقرار ‪.‬ي‬ ‫كب من النسبة ي‬ ‫المعي أ ر‬ ‫ر‬ ‫النظب‬ ‫ر‬ ‫البوتونات يف‬ ‫ﺔ تكون نسبة النيوترونات إىل ر‬ ‫يف بعض اأﻧ‬ ‫لك‬ ‫هذه الحالة يتحول أحد نيوترونات النواة إىل بروتون وينطلق نتيجة لذلك إلكبون والذي يسّم جسيم بيتا وذلك ي‬ ‫ه نسبة االستقرار‬ ‫والبوتونات ي‬ ‫تصبح النسبة ربي النيوترونات ر‬ ‫إعداد ‪ :‬محمود الحمد ‪51055849‬‬ ‫‪Page 10‬‬ Writing an Equation for Beta Decay 1- Write the balanced nuclear equation for the beta decay of yttrium-90, used in cancer treatment and as a colloidal injection into large joints to relieve the pain caused by arthritis. 2- Write the balanced nuclear equation for the beta decay of cobalt-60. Positron Emission ‫وف‬ ‫ ي‬. ‫الت تحقق االستقرار‬ ‫المعي أقل من النسبة ي‬ ‫ر‬ ‫النظب‬ ‫ر‬ ‫البوتونات يف‬ ‫يف بعض اأحيان تكون نسبة النيوترونات إىل ر‬ ‫البوتون الموجبة‬ ‫هذه الحالة يتحول أحد بروتونات النواة إىل نيوترون وينطلق نتيجة لذلك بوزيبون يحمل شحنة ر‬ ‫وئ‬ ‫ويعرف تفكك بيتا يف هذه الحالة بالتفكك البوزيب ي‬ 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 11 Gamma Emission Involves the radiation of high-energy γ photons (also called γ rays) from an excited nucleus. Just as an atom in an excited electronic state reduces its energy by emitting photons, a nucleus in an excited state lowers its energy by emitting γ photons, ‫ وتصدر إشعاعات جاما إذا تكونت النواة‬. ‫ه عبارة عن موجات كهروميناطسية ذات طاقة عالية‬ ‫إشعاعات جاما ي‬ ‫ عن تفكك الفا أو تفكك بيتا يف حالة مثارة فتفقد النواة إثارتها عن طريق التخلص من الطاقة يف‬Daughter ‫الناتجة‬ Parent ‫ه نفسها النواة اأم‬ ‫شكل إشعاعات جاما وبذلك فإنه بالنسبة الضمحالل جاما تكون النواة الناتجة ( الوليدة ) ي‬ ً ‫ولكنها ر‬.‫أكب استقرارا‬ Pure gamma emitters are rare, although gamma radiation accompanies most alpha and beta radiation. In radiology, one of the most commonly used gamma emitters is technetium (Tc). The unstable isotope of technetium is written as the metastable (symbol m) isotope technetium-99m, Tc-99m, By emitting energy in the form of gamma rays, the nucleus becomes more stable. 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 12 Summary of Radiation Types: When the nuclei of alpha, beta, positron, and gamma emitters emit radiation, new, more stable nuclei are produced. 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 13 PRACTICE PROBLEMS: 1- Balance the following nuclear equations (Find the missing Part): +× + × 2- Write the balanced nuclear equation for the alpha decay of americium-241 3- Write the balanced nuclear equation for the alpha decay of Po- 214. 4- Write the balanced nuclear equation for the beta decay of yttrium-90. 5- Write the balanced nuclear equation for the beta decay of chromium-51. 6- Write the balanced nuclear equation for manganese-49, which decays by emitting a positron. 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 14  7- Write the balanced nuclear equation for xenon-118, which undergoes positron emission. 8- Write the balanced nuclear equation for the beta decay of gold-198. 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 15 Producing Radioactive Isotopes Today, many radioisotopes are produced in small amounts by bombarding stable, nonradioactive isotopes with high-speed particles such as alpha particles, protons, neutrons, and small nuclei. When nonradioactive B-10 is bombarded by an alpha particle, the products are radioactive N-13 and a neutron. (NUCLEAR TRANSMUTATION: INDUCED CHANGES IN NUCLEI) The induced conversion of the nucleus of one element into the nucleus of another (the production of artificial radioisotopes),.‫أكب‬ َ ُ ‫غب تلقائية؛ حيث تقصف ذرة بجسيمات أصير تتحد لتكوين نواة مختلفة ر‬ ‫هو عملية ر‬ Notation for Transmutation Reactions 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 16 PRACTICE PROBLEMS: 1- Write the balanced nuclear equation for the bombardment of nickel-58 by a proton, which produces a radioactive isotope and an alpha particle. 2- The first radioactive isotope was produced in 1934 by the bombardment of aluminum-27 by an alpha particle to produce a radioactive isotope and one neutron. Write the balanced nuclear equation for this bombardment. 3- In an experimental treatment, a person is given boron-10, which is taken up by malignant tumors. When bombarded with neutrons, boron-10 decays by emitting alpha particles that destroy the surrounding tumor cells. Write the balanced nuclear equation for the reaction for this experimental procedure. 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 17 5.3 Radiation Measurement A radiation counter is used to check radiation levels Geiger counter One of the most common instruments for detecting beta and gamma radiation is the Geiger counter. It consists of a metal tube filled with a gas such as argon. When radiation enters a window on the end of the tube, it forms charged particles in the gas, which produce an electrical current. Each burst of current is amplified to give a click and a reading on a meter. 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 18  Joharah R. AlAjmi Biological Effect of Radiation Radiation source Radiation rate Absorbed dose Effective dose Radiation rate 𝑁𝑜. 𝑝𝑎𝑟𝑡𝑖𝑐𝑙𝑒𝑠 (𝑝𝑎𝑟𝑡𝑖𝑐𝑙𝑒) 𝑅𝑎𝑑𝑖𝑎𝑡𝑖𝑜𝑛 𝑟𝑎𝑡𝑒 = 𝑡𝑖𝑚𝑒 (𝑠) 1 particle/s = 1 Bq (Bequerel) 1 Ci (Curie) = 3.7 X 1010 Bq  Joharah R. AlAjmi Absorbed dose 𝐸𝑛𝑒𝑟𝑔𝑦 𝑜𝑓 𝑟𝑎𝑑𝑖𝑎𝑡𝑖𝑜𝑛 (𝐽) 𝐴𝑏𝑠𝑜𝑟𝑏𝑒𝑑 𝑑𝑜𝑠𝑒 = 𝑋 %𝐴𝑏𝑠𝑜𝑟𝑏𝑒𝑑 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑙𝑖𝑣𝑖𝑛𝑔 (𝑘𝑔) Energy of radiation = Energy/ particle x no. particles No. particles = radiation rate x time 1J/kg = 1Gy (Gray) = 100 rad Effective dose Effective dose = Absorbed dose x R. B. E. R. B. E. Relative Biological Effect (constant & unitless) Absorbed dose: Gy Effective dose: Sv (Seivert) Absorbed dose: rad Effective dose: rem Sv = 100 rem Units for Measuring Radiation - The activity (decay rate) of the sample is measured in terms of the number of nuclear disintegrations per second. - Units for measuring radiation activity include the following: curie (Ci)—the number of disintegrations that occurs in 1 s for 1 g of radium, equal to 3.7 × 1010 disintegrations/s Becquerel (Bq)—the SI unit of radiation activity, which is 1 disintegration/s ‫وحدة قياس النشاط االشعاعي هي البكريل والبكريل هو عدد اإلشعاعات التي تصدرها العينة المشعة‬ ‫في الثانية‬ rad (radiation absorbed dose)—measures the amount of radiation absorbed by a gram of material such as body tissues rem (radiation equivalent in humans)—measures biological effects of different kinds of radiation Measuring Radiation Damage The rem (radiation equivalent in humans) measures alpha particles, which do not penetrate the skin; however, if they enter the body, extensive damage may occur in tissues high-energy radiation, which causes more damage than alpha particles and includes beta particles, high-energy protons, and neutrons that travel into tissue gamma rays, which are damaging because they travel a long way through body tissue 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 19 To determine the equivalent dose or rem dose, The absorbed dose (rad) is multiplied by a factor that adjusts for biological damage caused by a particular form of radiation. Biological damage (rem) = Absorbed dose (rad) × Factor For beta and gamma radiation, the factor is 1. For high-energy protons and neutrons, the factor is about 10. For alpha particles, the factor is 20. Dosimeters Measure Radiation Exposure People who work in radiation laboratories wear dosimeters attached to their clothing. Dosimeters detect the amount of radiation exposure from the following: X-rays gamma rays beta particles Units of Radiation Measurement Often the measurement for an equivalent dose will be in millirems (mrem) Or microrems. 1 rem = 1000 mrem The SI unit is the sievert (Sv). 1 Sv = 100 rem 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 20 Lethal Doses of Radiation The larger the dose of radiation received at one time, the greater the effect on the body. Exposure to radiation of 5 Sv is expected to cause death in 50% of the people receiving the dose. This amount of radiation to the whole body is called the lethal dose for one-half the population, or LD50. 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 21 5.4 Half-Life of a Radioisotope The half-life of a radioisotope is the amount of time it takes for one- half of a sample to decay. ‫ ﺣ ﺚ ﺗﻨﺨﻔﺾ ﻓ ﻪ‬.‫ﻳﻨﺤﻞ ﻧﺼﻒ ﻋﺪد ذراﺗﻪ‬ ‫اﻟﻤﺸﻊ ﻟ‬ ‫ ﻫﻮ اﻟﺰﻣﻦ اﻟﺬي ﺤﺘﺎﺟﻪ اﻟﻌﻨ‬:( Half-Life) ‫ﻋﻤﺮ اﻟﻨﺼﻒ‬ ‫ وﻫﻮ ﻗ ﻤﺔ ﺛﺎﺑﺘﺔ و ﻣﻤ ة ﻟ ﻞ ﻋﻨ‬.‫اﻟ ﻤ ﺔ اﻟﻤﺸﻌﺔ إ اﻟﻨﺼﻒ‬ ‫أو ﻫﻮ ﻋ ﺎرة ﻋﻦ اﻟﻔ ة اﻟﺰﻣﻨ ﺔ اﻟ ﺗﻨﺨﻔﺾ ﺧﻼﻟﻬﺎ ﺷﺪﺗﻪ اﻹﺷﻌﺎﻋ ﺔ إ اﻟﻨﺼﻒ ﻤﻌ آﺧﺮ ﻓﺈن ﻋﻤﺮ اﻟﻨﺼﻒ ﻫﻮ اﻟﺰﻣﻦ‬ ‫اﻟﻼزم ﻟﺘﻔ ﻚ ﻧﺼﻒ ﻋﺪد ﻧﻮى اﻟﻌﻴﻨﺔ‬ In one half-life, the activity of an isotope decreases by half. The half-life of a radioisotope is the time for the radiation level (activity) to decrease (decay) to one-half of its original value. Example: ‫وﻫﺬا ﻌ أﻧﻪ إذا ﺎﻧﺖ ﻟﺪﻳﻨﺎ ﱢ‬ 131-‫ﻋﻴﻨﺔ ﺑﻬﺎ ﺛﻤﺎ ذرات ﻣﻦ اﻟﻴﻮد‬ 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 22  ً ‫ُ ﻤﻜﻦ ﺗﻄﺒﻴﻖ ﻫﺬە اﻟﻔﻜﺮة ﻧﻔﺴﻬﺎ إذا ﻗ ْﺴﻨﺎ ﱢ‬ ‫اﻟﻌﻴﻨﺔ ﺎﻟﺠﺮام ﺪ ﻣﻦ اﻟﺬرات‬ ِ Decay Curve A decay curve is a diagram illustrating the decay of a radioactive isotope. The decay curve for iodine-131 shows that one-half of the radioactive sample decays and one-half remains radioactive after each half-life of 8 days. 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 23 ‫‪Using Half-Lives of a Radioisotope‬‬ ‫ﻋﺪد اﻷﻧ ﺔ اﻟﻤﺘ ﻘ ﺔ )‬ ‫اﻟﻌﻼﻗﺔ ﺑ‬ ‫ﺗﻌ‬ ‫و‬ ‫ﻗﺎﻧﻮن اﻟﺘﻔ ﻚ اﻹﺷﻌﺎ ‪ :-‬ﺗﻌﺮف ﻫﺬە اﻟﻤﻌﺎدﻟﺔ ﻘﺎﻧﻮن اﻟﺘﻔ ﻚ اﻹﺷﻌﺎ‬ ‫ﻋﻤﻠ ﺔ اﻟﺘﺤﻠﻞ اﻹﺷﻌﺎ‬ ‫ﻣﻦ اﻟﻤﺎدة اﻟﻤﺸﻌﺔ و اﻟﺰﻣﻦ ‪ t‬اﻟﻤﺴﺘﻐﺮق‬ ‫‪N‬‬ ‫أو اﻟ ﻤ ﺔ اﻟﻤﺘ ﻘ ﺔ (‬ ‫إعداد ‪ :‬محمود الحمد ‪51055849‬‬ ‫‪Page 24‬‬ PRACTICE PROBLEMS: 1- The radioisotope strontium-90 has a half-life of 38.1 yr. If a sample contains 36 mg of Sr-90, how many milligrams will remain after 114.3 yr? 2- Phosphorus-32, a radioisotope used in the treatment of leukemia, has a half-life of 14.3 days. If a sample contains 8.0 mg of phosphorus-32, how many milligrams of phosphorus-32 remain after 42.9 days? 3- Iron-59 has a half-life of 44 days. If a nuclear laboratory receives a sample of 8.0 mg of iron-59, how many micrograms of iron-59 are still active after 176 days? 4- Iodine-123, used in the treatment of thyroid, brain, and prostate cancer, has a half-life of 13.2 h. How much of a 64-mg sample of I-123 is left after 26.4 hours? A. 32 mg B. 16 mg C. 8.0 mg D. 4.0 mg 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 25 ‫‪Dating Ancient Objects‬‬ ‫‪Radiological dating is a technique used by geologists, archaeologists,‬‬ ‫‪and historians to determine the age of ancient objects.‬‬ ‫‪The age of ancient objects is determined by measuring the amount of‬‬ ‫‪carbon-14 present.‬‬ ‫‪Carbon-14 is produced in the upper atmosphere by the bombardment‬‬ ‫‪of nitrogen-14 by high-energy neutrons from cosmic rays.‬‬ ‫‪Carbon-14 reacts with oxygen to form radioactive carbon dioxide‬‬ ‫‪which is absorbed by plants.‬‬ ‫ﺣﻴﻨﻤﺎ ﺗﺼﻄﺪم اﻷﺷﻌﺔ اﻟ ﻮﻧ ﺔ اﻟﺠﻮ ﺗ ﺘﺞ ﻧﻴﻮﺗﺮوﻧﺎت اﻟ ﺗﺘﻔﺎﻋﻞ ﺎﻟﺘﺎ ﻣﻊ ﻧﻴ وﺟ اﻟﺠﻮ ﻓﻴﺘﻜﻮن اﻟ ﻮن‪14 -‬‬ ‫ﺗﺘﺤﺪ ذرات اﻟ ﻮن‪ 14-‬اﻟﻨﺎﺗﺠﺔ ﻋﻦ اﻷﺷﻌﺔ اﻟ ﻮﻧ ﺔ ﻣﻊ اﻷ ﺴﺠ ﻟﺘﻜ ﻦ ﺛﺎ أ ﺴ ﺪ اﻟ ﻮن‪.‬ﺗﻤﺘﺺ اﻟﻨ ﺎﺗﺎت ﺛﺎ‬ ‫أ ﺴ ﺪ اﻟ ﻮن أﺛﻨﺎء ﻋﻤﻠ ﺔ اﻟﺘﻤﺜ ﻞ اﻟﻀﻮ ‪.‬و ﺘﻘﻞ اﻟ ﻮن‪ 14-‬ﻣﻦ اﻟﻨ ﺎﺗﺎت إ اﻹ ﺴﺎن واﻟﺤﻴﻮان ﻣﻦ ﺧﻼل اﻟﻐﺬاء‬ ‫ﺴ ﺔ اﻟ ﻮن‪ 14-‬إ اﻟ ﻮن‪ 12-‬ﺑﻮا ﺳ ﻄﺔ اﻟﻬﻮاء و ﺟﻤﻴﻊ اﻟ ﺎﺋﻨﺎت اﻟﺤ ﺔ ﻫﻮ ﻧﻔﺴﻪ‪.‬‬ ‫‪The uptake of carbon-14 in the CO2 stops when the plant dies.‬‬ ‫‪As the carbon-14 decays, the amount of radioactive carbon decreases.‬‬ ‫وﻋﻨﺪﻣﺎ ﺗﻤﻮت اﻟ ﺎﺋﻨﺎت اﻟﺤ ﺔ‪ ،‬ﻓﺈﻧﻬﺎ ﺗﺘﻮﻗﻒ ﻋﻦ اﻣﺘﺼﺎص اﻟ ﻮن‪ ، 14-‬وﺗ ﺪأ اﻟ ﻤ ﺔ اﻟﻤﺘ ﻘ ﺔ أﺟﺴﺎﻣﻬﺎ ﻋﻤﻠ ﺔ‬ ‫اﻹﺿﻤﺤﻼل ﻤﻌﺪل ﺛﺎ ﺖ ﻣﻊ اﻟﺰﻣﻦ ﻣﻦ ﺧﻼل اﻃﻼق ﺟﺴ ﻤﺎت ﺑ ﺘﺎ وﻻ ﻳﺘﻢ ﺗﻌ ﻀﻪ ﻤﺎ ﻫﻮ اﻟﺤﺎل ﻟﻠ ﺎﺋﻦ اﻟ ‪.‬ﻳﺘﻢ ﻗ ﺎس‬ ‫أﺷﻌﺔ اﻹﻟ وﻧﺎت )أﺷﻌﺔ ﺑ ﺘﺎ( ﻣﻦ ﻋﻴﻨﺔ ﻣﻌﺮوﻓﺔ اﻟﻮزن ﻓ ﻤﻜﻦ ﻣﻌﺮﻓﺔ ﻤ ﺔ اﻟ ﻮن‪ ١٤-‬اﻟ ﺎﻗ ﺔ اﻟﻌﻴﻨﺔ ‪.‬ﺑ ﻨﻤﺎ‬ ‫ﻳ اﻟ ﻮن‪ 12 -‬ﺛﺎﺑﺘﺎ ﺟﺴﻢ اﻟ ﺎﺋﻦ ﻗ ﻞ اﻟﻮﻓﺎة و ﻌﺪﻫﺎ‪.‬‬ ‫إعداد ‪ :‬محمود الحمد ‪51055849‬‬ ‫‪Page 26‬‬ In a process of carbon dating, scientists use the half-life of carbon-14 (5730 yr) to calculate the length of time since the plant died. Years elapsed = number of half-lives × 5730 Or 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 27 PRACTICE PROBLEMS: 1- A bone sample from the skeleton of a prehistoric animal has 25% of the activity of C-14 found in a living animal. How many years ago did the prehistoric animal die? 2- Suppose that a piece of wood found in a cave had one-eighth of its original carbon-14 activity. About how many years ago was the wood part of a living tree? 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 28 5.5 Medical Applications Using Radioactivity Radioisotopes with short half-lives are used in nuclear medicine because the cells in the body do not differentiate between nonradioactive atoms and radioactive atoms once incorporated into cells, the radioactive atoms are detected because they emit radiation, giving an image of an organ PRACTICE PROBLEMS: 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 29 Scans with Radioisotopes After the patient receives a radioisotope, the scanner moves slowly across the body above the region where the organ containing the radioisotope is located the radiation technologist determines the level and location of radioactivity emitted by the radioisotope the gamma rays emitted from the radioisotope can be used to expose a photographic plate, producing a scan of the organ A thyroid scan shows the accumulation of radioactive iodine-131 in the thyroid. 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 30 Positron Emission Tomography (PET) In positron emission tomography (PET), positron emitters with short half-lives are combined with body substances such as glucose Positron emitters with short half-lives such as carbon-11, oxygen-15, nitrogen-13, and fluorine-18 are used in an imaging method called positron emission tomography (PET) positrons are used to study brain function, metabolism, and blood flow These PET scans show a normal brain on the left and a brain affected by Alzheimer’s disease on the right. In positron emission tomography (PET), positrons are emitted from positron emitters such as carbon-11, oxygen-15, nitrogen-13, and fluorine-18 positrons combine with electrons to produce gamma rays are detected by computerized equipment to create a three- dimensional image of the organ 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 31 Computed Tomography (CT) a computer monitors the absorption of 30 000 X-ray beams directed at successive layers of the target organ based on the densities of the tissues and fluids in the organ, the differences in absorption of the X-rays provide a series of images of the organ A CT scan shows a tumor (yellow) in the brain. Magnetic Resonance Imaging (MRI) is an imaging technique that does not involve X-ray radiation is the least invasive imaging method available is based on the absorption of energy when protons in hydrogen atoms are excited by a strong magnetic field works because the energy absorbed is converted to color images of the body An MRI scan provides images of the heart and lungs. 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 32 5.6 Nuclear Fission and Fusion Nuclear Fission. ‫اﻟ ﺘﻠﺔ ﻧ ﺠﺔ ﺗﻔﺎﻋﻞ ﻧﻮوي ﻣﻌ‬ ‫ﻣﺘﻘﺎر ﺘ‬ ‫اﻻ ﺸﻄﺎر اﻟﻨﻮوي ﻫﻮ اﻧﻘﺴﺎم ﻧﻮاة ﺛﻘ ﻠﺔ إ ﻧﻮاﺗ‬ In nuclear fission, a large nucleus is bombarded with a small particle the nucleus splits into smaller nuclei and several neutrons, releasing large amounts of energy, called atomic energy When a neutron bombards U-235, an unstable nucleus of U-236 undergoes fission (splits) smaller nuclei are produced such as Kr-91 and Ba-142 the neutrons emitted have high energy and bombard more U- 235 nuclei A typical reaction for nuclear fission is: ‫ اﻟ ﺗﺘﺤﻮل إ‬235- ‫ ﺑ ﻴﻮﺗﺮون ﻓﺄن اﻟﻨﻴﻮﺗﺮون ﺪﺧﻞ إ ﻧﻮاة ذرة اﻟﻴﻮراﻧﻴﻮم‬235- ‫ﻋﻨﺪﻣﺎ ﺗﻘﺬف ﻧﻮاة ذرة اﻟﻴﻮراﻧﻴﻮم‬- (Y) ، (X) ‫ ﺗ ﺸﻄﺮ ﻌﺪﻫﺎ اﻟﻨﻮاة إ ﻧﻮاﺗ‬، ‫ ﺛﺎﻧ ﺔ‬10-12 ‫ وﻫﻮ ﻧﻈ ﻏ ﻣﺴﺘﻘﺮ ﻻ ﻳ ﺪ ﻣﺪة ﻘﺎؤە ﻋﻦ‬236-‫ﻧﻄ اﻟﻴﻮراﻧﻴﻮم‬.‫ﺴﻤ ﺎن ﺷﻈﺎ ﺎ اﻷ ﺸﻄﺎر اﻟﻨﻮوي‬ 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 33 Missing Mass: If we could determine the mass of the products krypton, barium, and three neutrons, we would find that their total mass is slightly less than the mass of the starting materials the missing mass has been converted into an enormous amount of energy consistent with the famous equation derived by Albert Einstein: E = mc2 Chain Reaction In a nuclear chain reaction, the fission of each uranium-235 atom produces three neutrons that cause the nuclear fission of more and more uranium-235 atoms. 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 34 ‫إعداد ‪ :‬محمود الحمد ‪51055849‬‬ ‫‪Page 35‬‬ ‫‪A chain reaction occurs when‬‬ ‫‪ a critical mass of uranium undergoes fission‬‬ ‫‪ there is a rapid increase in the number of high-energy neutrons‬‬ ‫‪available to react with more uranium‬‬ ‫‪ To sustain a nuclear chain reaction, sufficient quantities of U-235‬‬ ‫‪must provide a critical mass in which almost all the neutrons‬‬ ‫‪immediately collide with more U-235 nuclei‬‬ ‫‪Nuclear Fusion‬‬ ‫اﻷﻧﺪﻣﺎج اﻟﻨﻮوي‬ ‫ﻟﺘﻜ ﻦ ﻧﻮاة أﺛﻘﻞ ﻣﻨﻬﻤﺎ‪.‬‬ ‫ﺧﻔ ﻔﺘ‬ ‫‪ -‬ﻫﻮ ﺗﻔﺎﻋﻞ ﻧﻮوى ﻟﺪﻣﺞ ﻧﻮاﺗ‬ ‫ﻣﺘﻮﺳﻄﺘ ‪.‬‬ ‫‪ -‬وﻫﻮ ﻋﻜﺲ اﻻ ﺸﻄﺎر اﻟﻨﻮوي اﻟﺬي ﺗﻨﻘﺴﻢ ﻓ ﻪ ﻧﻮاة ﺛﻘ ﻠﺔ إ ﻧﻮاﺗ‬ ‫ﻣﺜﺎل‪:‬‬ ‫‪-‬إذا ﺗﻢ دﻣﺞ ذرة اﻟﺪﻳﻮﺗﺮوم ﻣﻊ ذرة اﻟ ﺗﻴﻮم ﻳﺘﻜﻮن ﻧﻮاة ذرة اﻟﻬ ﻠﻴﻮم واﻧﻄﻼق ﻧﻴ ون‬ ‫‪ -‬ﻫﺬا اﻹﻧﺪﻣﺎج اﻟﻨﻮوى ﻤﻜﻦ ﺗﻤﺜ ﻠﻪ ﺎﻟﻤﻌﺎدﻟﺔ اﻟﻨﻮو ﺔ اﻟﺘﺎﻟ ﺔ‪:‬‬ ‫‪ -‬ﻟﺤﺪوث اﻻﻧﺪﻣﺎج اﻟﻨﻮوي ﻠﺰم ﺗﻮﻓﺮ درﺟﺔ ﺣﺮارة ﻋﺎﻟ ﺔ ﺟﺪا‪.‬‬ ‫‪ -‬وﻧﻈﺮا ﻻرﺗﻔﺎع درﺟﺔ اﻟﺤﺮارة ﻫﺬة ‪ ،‬ﻓﺄن اﻻﻧﺪﻣﺎج اﻟﻨﻮوي ﺼﻌﺐ ﺗﺤﻘ ﻘﻪ اﻟﻤﺨﺘ ات ﻏ أن ﻫﺬا اﻟﺘﻔﺎﻋﻞ ﺤﺪث‬ ‫داﺧﻞ اﻟﺸﻤﺲ ) ﻤﺎ ﺤﺪث داﺧﻞ اﻟﻨﺠﻮم( ﺣ ﺚ ﺗﺼﻞ درﺟﺔ اﻟﺤﺮارة إ ﻣﻼﻳ اﻟﺪرﺟﺎت اﻟﻤﺌ ﺔ‪.‬‬ ‫إعداد ‪ :‬محمود الحمد ‪51055849‬‬ ‫‪Page 36‬‬ Nuclear fusion occurs at extremely high temperatures (100 000 000 °C) combines small nuclei into larger nuclei releases large amounts of energy occurs continuously in the Sun and stars. In a fusion reaction, large amounts of energy are produced as hydrogen isotopes combine to form helium. Less waste is produced in a fusion reaction than in a fission reaction. 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 37 ‫إعداد ‪ :‬محمود الحمد ‪51055849‬‬ ‫‪Page 38‬‬ Nuclear Power Plants In nuclear power plants, fission is used to produce energy the quantity of U-235 is held below its critical mass control rods in the reactor absorb neutrons to slow the fission process the heat produced in the fission process is used to make steam that drives a generator and produces electricity Heat from nuclear fission is used to generate electricity. 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 39 PRACTICE PROBLEMS: 1- For each of the following, indicate whether it describes nuclear fission or nuclear fusion: A. A nucleus splits. B. Large amounts of energy are released. C. Small nuclei form larger nuclei. D. Hydrogen nuclei react. E. Several neutrons are released. A. A nucleus splits. fission B. Large amounts of energy are released. fission and fusion C. Small nuclei form larger nuclei. fusion D. Hydrogen nuclei react. fusion E. Several neutrons are released. fission 2- Supply the missing atomic symbol to complete the equation for the following nuclear fission reaction: 51055849 ‫ محمود الحمد‬: ‫إعداد‬ Page 40