Radioactive Decay Processes
Radioactive Decay Processes
Amelia Beissler - Fall 2024
The Main Idea
When an atom or compound has extra particles, whether that be an electron, proton, or neutron, it is defined as unstable. This means that the binding energy of the atom and the strong and weak nuclear forces struggle to keep the atom together due to the excess mass. This can lead to spontaneous reactions, where an atom will release a particle or gamma ray in order to lose energy and return to a stable state or transform into a different nuclide that is more stable. Out of all the naturally occurring elements, there are about 251 isotopes that are stable and 28 unstable elements, the most notable among those being Uranium and Thorium.
A key trait of radioactive decay processes is the idea that they are spontaneous and there is no way to truly predict when a molecule will decay. However, with things like the decay constant and half-life, there are ways to predict how a larger group of molecules will behave. The half life is an intrinsic property of each isotope, an amount of time that signifies how long it will take for half of the atoms or molecules to decay into more stable nuclides. The decay constant can be derived from the half life, and helps predict decaying behaviors.
The actual radioactive decay process starts with an excited, unstable parent nuclide. As stated above, at a completely spontaneous point in time, the parent nuclide will decay releasing a particle or gamma ray to return the atom to a more stable state. With this reaction, the energy that is released is positive, which means it is exothermic and does not require any energy to be input for the reation to occur. Sometimes, especially with more atoms, it also takes a few decay processes to return the atom to a stable state.
Spontaneous fission is sometimes considered a radioactive decay process, but not always. In this page, the four main types of decays will be discussed: alpha, beta plus, beta minus, and electron capture decay. More information on fission can be found under the same subcategory as this one.
Beta Decay
Beta Plus (Positron) Decay
Beta Minus Decay
Alpha Decay
Alpha decay is common with heavier nuclides, usually bismuth and above, and they usually decay until they reach a stable lead isotope. An alpha particle, which is composed of two protons and two neutrons tightly bound together, is born with a daughter nuclide that has an atomic number two less than its parent nuclide and a mass number four less than its parent. A basic example of an alpha decay reaction is below.
<math> XZA \rightarrow YZ-2A-4 + \alpha24 <math>
Electron Capture
Gamma Decay
See also
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