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Isotones are nuclides with the same number of neutrons but differing numbers of protons. Isotones neighbor each other horizontally. Examples include carbon-14, nitrogen-15, and oxygen-16 in the table above. Isobars are nuclides with the same number of nucleons (i.e. mass number) but different numbers of protons and neutrons. Isobars neighbor ...
28 Si (the most abundant isotope, at 92.23%), 29 Si (4.67%), and 30 Si (3.1%) are stable. The longest-lived radioisotope is 32 Si, which is produced by cosmic ray spallation of argon . Its half-life has been determined to be approximately 150 years (with decay energy 0.21 MeV), and it decays by beta emission to 32 P (which has a 14.27-day half ...
A nuclide is defined conventionally as an experimentally examined bound collection of protons and neutrons that either ... Many of these in ... 30 Si: 30: 14: 16: 8 ...
[13] 32 Si undergoes low-energy beta decay to 32 P and then stable 32 S. 31 Si may be produced by the neutron activation of natural silicon and is thus useful for quantitative analysis; it can be easily detected by its characteristic beta decay to stable 31 P, in which the emitted electron carries up to 1.48 MeV of energy. [34]
Neutrons stabilize the nucleus, because they attract protons, which helps offset the electrical repulsion between protons. As a result, as the number of protons increases, an increasing ratio of neutrons to protons is needed to form a stable nucleus; if too many or too few neutrons are present with regard to the optimum ratio, the nucleus ...
Except 20, 50 and 82 (all these three numbers are magic numbers), all other neutron numbers have at most 4 stable nuclides (in the case of 20, there are 5 stable nuclides 36 S, 37 Cl, 38 Ar, 39 K, and 40 Ca, and in the case for 50, there are 5 stable nuclides: 86 Kr, 88 Sr, 89 Y, 90 Zr, and 92 Mo, and 1 radioactive primordial nuclide, 87 Rb).
For this reason, one or more neutrons are necessary for two or more protons to be bound into a nucleus. As the number of protons increases, so does the ratio of neutrons to protons necessary to ensure a stable nucleus (see graph). For example, although the neutron–proton ratio of 3 2 He is 1:2, the neutron–proton ratio of 238 92 U is ...
For example, 35 Cl (17 protons and 18 neutrons) has a mass number of 35 and an isotopic mass of 34.96885. [7] The difference of the actual isotopic mass minus the mass number of an atom is known as the mass excess , [ 8 ] which for 35 Cl is –0.03115.