Examples of nucleon in the following topics:
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- The component parts are neutrons and protons, which collectively are called nucleons.
- Conversely, energy is released when a nucleus is created from free nucleons or other nuclei—known as the nuclear binding energy.
- It is the attractive force that binds together particles known as quarks (to form the nucleons themselves).
- Similarly, even though nucleons are made of quarks in combinations which cancel most gluon forces (they are "color neutral"), some combinations of quarks and gluons leak away from nucleons in the form of short-range nuclear force fields that extend from one nucleon to another nucleon in close proximity.
- A model of the atomic nucleus showing it as a compact bundle of the two types of nucleons: protons (red) and neutrons (blue).
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- Through radioactive decay, nuclear fusion and nuclear fission, the number of nucleons (sum of protons and neutrons) is always held constant.
- In physics and chemistry there are many conservation laws—among them, the Law of Conservation of Nucleon Number, which states that the total number of nucleons (nuclear particles, specifically protons and neutrons) cannot change by any nuclear reaction.
- Chain reactions of nuclear fission release a tremendous amount of energy, but follow the Law of Conservation of Nucleon Number.
- Finally, nuclear fusion follows the Law of Conservation of Nucleon Number.
- Thus, the number of nucleons before and after fission and fusion is always constant.
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- A nucleus weighs less than its sum of nucleons, a quantity known as the mass defect, caused by release of energy when the nucleus formed.
- Once this energy, which is a quantity of joules for one nucleus, is known, it can be scaled into per-nucleon and per-mole quantities.
- To convert to joules per nucleon, simply divide by the number of nucleons.
- This graph shows the nuclear binding energy (in MeV) per nucleon as a function of the number of nucleons in the nucleus.
- Notice that iron-56 has the most binding energy per nucleon, making it the most stable nucleus.
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- The same force also pulls the nucleons, or neutrons and protons, together.
- When a nucleon is added to a nucleus, the nuclear force attracts it to other nucleons, but primarily to its immediate neighbors due to the short range of the force.
- The nucleons in the interior of a nucleus have more neighboring nucleons than do those on the surface.
- The binding energy per nucleon generally increases with the size of the nucleus but approaches a limiting value corresponding to that of a nucleus with a diameter of about four nucleons.
- The electrostatic energy per nucleon increases without limit as nuclei get larger due to the electrostatic force.
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- The strong nuclear force is the force between two or more nucleons.
- This force binds protons and neutrons together inside the nucleus, and it is most powerful when the nucleus is small and the nucleons are close together.
- The resulting elements (shown here as Kr-92 and Ba-141) do not contain as many nucleons as U-236, with the remaining three neutrons being released as high-energy particles, able to bombard another U-235 atom and maintain a chain reaction.
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- Alpha decay is by far the most common form of cluster decay, in which the parent atom ejects a defined daughter collection of nucleons, leaving another defined product behind (in nuclear fission, a number of different pairs of daughters of approximately equal size are formed).
- In theory it can occur only in nuclei somewhat heavier than nickel (element 28), in which overall binding energy per nucleon is no longer a minimum and the nuclides are therefore unstable toward spontaneous fission-type processes.
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- Like electrons, nucleons can be arranged in shells that are most stable in certain numbers.
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- Beta decay does not change the number of nucleons, A, in the nucleus; it changes only its charge, Z.
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- Helium has an extremely low mass per nucleon and therefore is energetically favored as a fusion product.