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Most stable nuclides have roughly equal numbers of protons and neutrons, so the line for which Z = N forms a rough initial line defining stable nuclides. The greater the number of protons, the more neutrons are required to stabilize a nuclide; nuclides with larger values for Z require an even larger number of neutrons, N > Z, to be stable. The ...
An example is calcium-40, with 20 neutrons and 20 protons, which is the heaviest stable isotope made of the same number of protons and neutrons. Both calcium-48 and nickel-48 are doubly magic because calcium-48 has 20 protons and 28 neutrons while nickel-48 has 28 protons and 20 neutrons. Calcium-48 is very neutron-rich for such a relatively ...
A table or chart of nuclides is a two-dimensional graph of isotopes of the elements, in which one axis represents the number of neutrons (symbol N) and the other represents the number of protons (atomic number, symbol Z) in the atomic nucleus. Each point plotted on the graph thus represents a nuclide of a known or hypothetical chemical element.
The continuous line passing below most of the nuclides comprises the positions on the graph of the (mostly hypothetical) nuclides for which proton number would be the same as neutron number. The graph reflects the fact that elements with more than 20 protons either have more neutrons than protons or are unstable.
A type of subatomic particle consisting of two protons and two neutrons bound together into a particle identical to the nucleus of a helium-4 ion. It has a charge of +2 e and a mass of 4 u . Alpha particles are classically produced in the process of radioactive alpha decay , but may also be produced in other ways and given the same name.
According to the shell model, protons or neutrons tend to form pairs of opposite total angular momentum.Therefore, the magnetic moment of a nucleus with even numbers of each protons and neutrons is zero, while that of a nucleus with an odd number of protons and even number of neutrons (or vice versa) will have to be that of the remaining unpaired nucleon.
Avogadro constant (N A) The ratio of the number of discrete constituent particles (such as molecules, atoms, or ions) to the amount of a substance, defined as exactly 6.022 140 76 × 10 23 mol −1. Avogadro number The number of discrete constituent particles in one mole of a substance, defined as exactly 6.02214076 × 10 23.
Eddington originally calculated it as about 1.57 × 10 79; current estimates make it approximately 10 80. [ 1 ] The term is named for British astrophysicist Arthur Eddington , who in 1940 was the first to propose a value of N Edd and to explain why this number might be important for physical cosmology and the foundations of physics .