![]() ![]() ![]() Linear and angular momentum are conserved, too. You can see from the equation that total charge is conserved. It is instructive to examine conservation laws related to decay. Then since four nucleons have broken away from the original 239, its atomic mass would be 235. So if you were told that decays and were asked to write the complete decay equation, you would first look up which element has two fewer protons (an atomic number two lower) and find that this is uranium. Where Y is the nuclide that has two fewer protons than X, such as Th having two fewer than U. The decay equations for these two nuclides are One example of decay is shown in Figure 1 for. In alpha decay, a nucleus simply breaks away from the parent nucleus, leaving a daughter with two fewer protons and two fewer neutrons than the parent (see Figure 2). No decays are shown in the figure, because they do not produce a daughter that differs from the parent. Beta decay is a little more subtle, as we shall see. The daughters of decay have one less neutron and one more proton than their parent. This seems reasonable, since we know that decay is the emission of a nucleus, which has two protons and two neutrons. Note that the daughters of decay shown in Figure 1 always have two fewer protons and two fewer neutrons than the parent. A stable isotope of lead is the end product of the series. You can see why radium and polonium are found in uranium ore. Note that some nuclides decay by more than one mode. The type of decay for each member of the series is shown, as well as the half-lives. Nuclides are graphed in the same manner as in the chart of nuclides. The decay series produced by 238U, the most common uranium isotope. The decay series ends with, a stable isotope of lead. The decay of radon and its daughters produces internal damage. Since radon is a noble gas, it emanates from materials, such as soil, containing even trace amounts of and can be inhaled. Radon gas is also produced ( in the series), an increasingly recognized naturally occurring hazard. The decay series that starts from is of particular interest, since it produces the radioactive isotopes and, which the Curies first discovered (see Figure 1). Others, such as, decay to another unstable nuclide, resulting in a decay series in which each subsequent nuclide decays until a stable nuclide is finally produced. For example, is unstable and decays directly to, which is stable. Some radioactive nuclides decay in a single step to a stable nucleus. We call the original nuclide the parent and its decay products the daughters. Unstable nuclides decay (that is, they are radioactive), eventually producing a stable nuclide after many decays. Some nuclides are stable, apparently living forever. ![]() In this section, we explore the major modes of nuclear decay and, like those who first explored them, we will discover evidence of previously unknown particles and conservation laws. Nuclear decay gave the first indication of the connection between mass and energy, and it revealed the existence of two of the four basic forces in nature. Nuclear decay has provided an amazing window into the realm of the very small. Calculate the energy emitted during nuclear decay. ![]()
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