|
|
This is only a preview of the paper
Click here to register and get the full text.
Existing members click here to login
|
|
|
What is radioactivity? Who discovered it? When? How? Spontaneous emission of radiation, either directly from unstable atomic nuclei or as a consequence of a nuclear reaction is a phenomenon called radioactivity. Nuclear reactions are changes occurring in the nucleus of an atom. Some nuclei are unstable and may spontaneously change their composition through the emission of radiation. Radioactivity was discovered accidentally in 1896 by the French physicist/chemist, Antoine-Henri Becquerel. He had stored a mineral containing uranium next to a photographic plate covered in black paper in a drawer. When the plate was developed, a foggy image of the mineral was visible. Antoine-Henri Becquerel What is a radioisotope? Radioisotopes are unstable radioactive isotopes that either occur naturally or are produced by bombarding small amounts of particular elements with neutrons (usually emitted from a nuclear reactor). Radioactive isotopes (often referred to as radioisotopes or radionuclides) play an important part in the technologies that provide us with food, water and good health. In medicine, radioisotopes are widely used for diagnosis and research. In food preservation, radioisotopes are used to inhibit the sprouting of root crops after harvesting, to kill parasites and pests, and to control the ripening of stored fruit and vegetables. In agriculture and animal husbandry, radioisotopes also play an important role. They are used to produce high yielding, disease and weather resistant varieties of crops. Industrially, and in mining, they are used to examine welds, to detect leaks, to study the rate of wear of metals, and for on-stream analysis of a wide range of minerals and fuels. Environmentally, radioisotopes are used to trace and analyse pollutants, to study the movement of surface water, and to measure water runoffs from rain and snow, as well as the flow rates of streams and rivers. Trace radioisotopes are those that occur in minute amounts in nature either due to inherent rarity or to half-lifes that are significantly shorter than the age of the Earth. Synthetic isotopes are not naturally occurring on Earth, but they can be created via nuclear reactions. List ten commercial radioisotopes and their uses. Use a table to present your information. USES OF RADIOISOTOPES Radioisotope Use Americium-241 Used in smoke detectors; determining where oil wells should be drilled. Californium-252 Used to measure the mineral content of coal ash and the moisture of materials stored in silos. Chromium-51 Used in research in red blood cell survival studies. Iodine-131 Used to diagnose and treat thyroid disorders. Krypton-85 Used in indicator lights in appliances like clothes washers and dryers, stereos and coffee makers; and to measure dust and pollutant levels. Plutonium-238 Has safely powered at least 20 NASA spacecraft since 1972. Technetium-99 The most widely used radioactive isotope for diagnostic studies in nuclear medicine. Different chemical forms are used for brain, bone, liver, spleen, and kidney imaging, and also for blood flow studies. Uranium-238 Used in dental fixtures like crowns and dentures to provide natural colour and brightness; and in fuel for nuclear power plants and naval nuclear propulsion. Xenon-133 Used in nuclear medicine for lung ventilation and blood flow studies. Thorium-229 Prolongs the life of fluorescent lights. Plutonium Uranium Draw up a table of the three types of radiation. Include: their name, symbol(s), identity, relative charge, relative mass, and penetrating power. Name ALPHA PARTICLES BETA PARTICLES GAMMA RAYS Symbol(s) Identity Releative Charge 2+ charge 1- charge No charge Relative Mass Mass of 4 amu* No mass Penetrating Power Least penetrating type of radiation; travel about 5 cm through air, easily stopped or absorbed by a thin sheet of paper or skin. More penetrating than α particles; travel about 100cm through air, stopped by a 5 mm thick sheet of aluminium. Most penetrating type of radiation; can pass through several cm of lead or more than a metre of concrete. Use equations to demonstrate the decay of three radioisotopes, by either alpha or beta decay. An alpha particle is simply a typical helium nucleus, 2He4. It is sometimes written 2a4 or simply a. This combination of two protons and two neutrons is particularly stable, and readily escapes from radioactive isotopes instead of other less-stable combinations of protons and neutrons. This is a demonstration of alpha decay, in which radium has lost a helium particle (2 protons and 2 neutrons) to form radon. Radium’s atomic number is two more than Radon’s, indicating it has lost two protons.
Approximate Word count = 2892
Approximate Pages = 11.6
(250 words per page double spaced)
|
|
|
|
|
|