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Slide 2 A radioisotope is a radioactive isotope of an element. Ex: A natural radioisotope of Uranium-238 is Uranium-235 Radioisotopes are constantly decaying into other elements. The half-life of a radioactive isotope is the time it takes for one half of a sample of that isotope to decay. Question: If you have 8 grams of an element and its half-life is 1 day, how many grams are left after 3 days? Radioisotopes Slide 3 - Carbon-14 is a well known radioactive isotope that is used in radiocarbon dating. - It has a half-life of 5730 years. -Based on its half-life, scientists can determine the age of plant, animal, and object remains. -Note: this works up to 30,000 years Radioisotopes Slide 4 Slide 5 The SI unit of radioactivity is the becquerel, named after Henri Becquerel. A more widely used unit is the curie (Ci), named after Pierre and Marie Curie. The rem (roentgen equivalent for man) measures radiation exposure in humans. Slide 6 A dosimeter measures the total amount of radiation that a person has received. A Geiger counter detects radiation. High energy radiation (such as gamma) forms free radicals inside the body and can destroy tissue. NOTE: Radiation damage may affect an organism directly or it may affect the organisms offspring, if reproductive cells are affected. Slide 7 In spite of the hazards of radiation, radioisotopes are very beneficial in medicine, agriculture, and industry. --- Radiotracers use radioactive substances to follow a specified substance as it moves through a natural system. --- Radiotherapy uses radioactive substances to help treat cancer. --- Radiation can be used to help preserve foods such as strawberries. Slide 8 Harnessing the Nucleus Slide 9 Nuclear reactors are not able to explode like an atomic bomb because they are regulated by control rods that slow down the speed of the neutrons. Slide 10 Harnessing the Nucleus Slide 11