This may seem to remove the threat from alpha particles, but it is only from external sources. They are also stopped by the outer layer of dead skin on people. Alpha particles have the least penetration power and can be stopped by a thick sheet of paper or even a layer of clothes. They collide with molecules very quickly when striking matter, add two electrons, and become a harmless helium atom. That same large size of alpha particles, however, makes them less able to penetrate matter. Because of the large mass of the alpha particle, it has the highest ionizing power and the greatest ability to damage tissue. Alpha particles have approximately four times the mass of a proton or neutron and approximately 8,000 times the mass of a beta particle. In general, the greater mass present, the greater the ionizing power, and the lower the penetration power.Ĭomparing only the three common types of ionizing radiation, alpha particles have the greatest mass. The more material the radiation can pass through, the greater the penetration power and the more dangerous it is. How thick of a wall do you need to hide behind to be safe? The ability of each type of radiation to pass through matter is expressed in terms of penetration power. Much of the threat from radiation is involved with the ease or difficulty of protecting oneself from the particles. The greater the likelihood that damage will occur by an interaction is the ionizing power of the radiation. When a radiation particle interacts with atoms, the interaction can cause the atom to lose electrons and thus become ionized. The ability of radiation to damage molecules is analyzed in terms of what is called ionizing power. In most cases, radiation will damage a single (or very small number) of cells by breaking the cell wall or otherwise preventing a cell from reproducing. Large amounts of radiation are very dangerous, even deadly. These interactions can alter molecular structure and function cells no longer carry out their proper function and molecules, such as DNA, no longer carry the appropriate information. The damage to living systems is done by radioactive emissions when the particles or rays strike tissue, cells, or molecules and alter them. With all the radiation from natural and man-made sources, we should quite reasonably be concerned about how all the radiation might affect our health. The Ionizing and Penetration Power of Radiation Some later time, alpha particles were identified as helium-4 nuclei, beta particles were identified as electrons, and gamma rays as a form of electromagnetic radiation like x-rays, except much higher in energy and even more dangerous to living systems. These particles were named using the first three letters of the Greek alphabet. beta particles \(\left( \beta \right)\).When these emissions were originally observed, scientists were unable to identify them as some already known particles and so named them: In natural radioactive decay, three common emissions occur. All of these elements can go through nuclear changes and turn into different elements. All nuclei with 84 or more protons are radioactive, and elements with less than 84 protons have both stable and unstable isotopes. In these changes, the nucleus, which contains the protons that dictate which element an atom is, is changing. That is because in all other types of changes discussed, only the electrons were changing. In our studies up to this point, atoms of one element were unable to change into different elements. Many nuclei are radioactive that is, they decompose by emitting particles and in doing so, become a different nucleus. Write nuclear equations for alpha and beta decay reactions.Express the changes in the atomic number and mass number of a radioactive nuclei when an alpha, beta, or gamma particle is emitted.Compare qualitatively the ionizing and penetration power of alpha particles \(\left( \alpha \right)\), beta particles \(\left( \beta \right)\), and gamma rays \(\left( \gamma \right)\).The U-236 nucleus then rapidly breaks apart into two smaller nuclei (in this case, Ba-141 and Kr-92) along with several neutrons (usually two or three), and releases a very large amount of energy.Īmong the products of Meitner, Hahn, and Strassman’s fission reaction were barium, krypton, lanthanum, and cerium, all of which have nuclei that are more stable than uranium-235.\) \): When a slow neutron hits a fissionable U-235 nucleus, it is absorbed and forms an unstable U-236 nucleus.
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