Chapter 24 Applications of Nuclear Chemistry. Read introduction page 776 Quick review of chapter 3 notes. Most elements and their isotopes found naturally are stable. Many radioactive elements and isotopes are man made. A few, such as uranium, are found naturally.
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Chapter 24 Applications of Nuclear Chemistry Read introduction page 776 Quick review of chapter 3 notes
Most elements and their isotopes found naturally are stable. • Many radioactive elements and isotopes are man made. • A few, such as uranium, are found naturally. • The nuclei of unstable elements emit atomic particles to change the number of protons and eventually become a stable element.
Radioisotope – a radioactive isotope of an element • Rubidium (Rb) has two naturally occurring isotopes. (Rb-87 27.85% and Rb-85 72.15%) • Rb-85 is stable and Rb-87 is radioactive. It emits a beta particle and has a half life of 60 billion years. (show nuclear equation for this decay)
Half-life • It is the time it take for ½ of a sample of a radioisotope to decay. • See sample problem on page 780. • Can also use the equation given below • Amount left = (starting amount)(.5)(# of half-lives)
Carbon 14 Dating • C-14 is produced by cosmic rays and atmospheric N-14. (N-14 absorbs a neutron and ejects a proton) • C-14 is oxidized in atmosphere to 14CO2. • C-14 decays to N-14 by the emitting a beta particle. (show nuclear reaction) • The C-14 concentration of C-14 in atmosphere is constant (The production and breakdown is a steady state process) • C-14 has a half-life of 5730 years. • When C-14 is taken up by plants the decay process is the same (good for dating once living things).
Nuclear Bombardment Reactions • Alpha particles can be accelerated with particle accelerators and driven into the nucleus of an atom. This creates an unstable isotope which breaks down. • Neutrons, because they are neutral) can be absorbed into a nucleus without being accelerated.
Biological Effects of Radiation • Alpha particles are very weak and not harmful unless produced within the body. • Beta particles can damage skin • Gamma rays are very penetrating and harmful • Dosimeter – used to measure the total radiation a person is exposed to in a given amount of time
Gamma rays (ionizing radiation) cuts through molecules producing ions and free radicals. • Destruction of tissue – especially rapidly multiplying cells (lymph nodes) • Marie Curie and her daughter both died of leukemia • Can also result in genetic damage
Detection of Radiation • Radiation also ionizes particles in the air and makes it more conductive to electricity. • Smoke detectors rely on this and so do Geiger counters.
Beneficial Uses of Radioisotopes • Radiotracers are placed in the body to track the movement and absorption of a particular element. (example I-131 to study thyroid) • Radiation is often used for cancer treatment because tumors are runaway abnormal cell growth which are more susceptible to radiation. • Radiation can extend the shelf life of many foods.
Radon – The Hidden Hazard • Granite bedrock under much of the US contains small amounts of uranium-238. • One of the decay products in Radon-222 which is a radioactive noble gas. • This percolates up through the soil into basements. • While in your lungs it changes into another elements which sticks to the lung and is the second leading cause of lung cancer.
Nuclear Energy • Nuclear fission is the splitting of large elements such as uranium into smaller ones. • A nuclear reactor controls the U-235 fission reaction by controlling the number of neutrons with control rods.
Nuclear Accidents • Critical mass – the mass of uranium necessary to create and runaway nuclear reaction (atomic bomb) • The fuel rods in a nuclear reactor do not contain enough uranium to reach critical mass • 1979 – Three Mile Island, Pennsylvania plant overheated • 1986 – Chernobly, Ukraine plant had a graphite fire which resulted in meltdown
Nuclear Fusion • Small atoms such as hydrogen adding to produce larger atoms. (the sun) • An example is the hydrogen bomb. • Requires very high temps (40 million C) • We do not have the technology as yet to produce our electricity with a fusion reactor.
E = mc2 • All energy transformations result in a change of mass. The mass change in most situations is so small we cannot measure it. • The energy given off in nuclear reactions is so great we can detect the change in mass. • To use this equation E should be in Joules, mass in kilograms, and the speed of light (c) is 3 x 108 meters per second.
Cold Fusion, the unfulfilled dream, may not be possible.Fusion could be a way out of our energy dilemma.