Chlorine nuclides

Although 28Mg is farther from the band of stability than is 27Mg, the former is an even-even nuclide while the latter is an even-odd nuclide. As we have seen earlier, even-even nuclides tend to be more stable. Consequently, the even-even effects here outweigh the fact that 28Mg is farther from the band of stability. Another interesting case is shown by considering these isotopes of chlorine ... 

Isotopes of a chemical element are nuclides with the same number of protons (Z) but a different number of neutrons N) in the atomic nucleus. Isotopes of a chemical element (e.g., H and of hydrogen Cl and Cl of chlorine or Fe, Fe, Fe and Fe of iron, respectively) have the same number of protons (Z) and possess the same chemical properties, but differ in the number of neutrons (N) and thus in the mass number (A). With increasing Z, the number of neutrons in a stable atomic nucleus is higher than the number of protons. For mono-isotopic elements. 

Phosgene containing the short-lived radioactive nuclide C has been prepared by zinc reduction of cyclotron-produced ( N(p,a) C) CO j to CO, followed by chlorination to COClj by passage of the gaseous labelled CO over heated PtCl [429,1729,1731], or by... 

The development of more sensitive ways to measure levels of radioactive substances has allowed scientists to take advantage of the decay of nuclides other than carbon-14. For example, chlorine-36 can be used to date ground water, marine sediments can be dated by measuring levels of beryllium-11 and aluminum-26, and krypton-81 has been used to estimate the age of glacial ice. 

In practice, the SSNMR spectra of the quadrupolar halogen nuclei in non-cubic environments are expected to be dominated by the QI. This is due to the moderately large Q associated with each nuclide, coupled with typically modest CSA contributions (t)q5ical CSAs are observed to be on the order of 10 -10 ppm). However, recent work in particular vide infra) has shown that there are in fact many examples, particularly for chlorine-35/37, where contributions from CSA... 

The most exciting recent developments in the field of SSNMR of the quadrupolar halogens, in our opinion, relate to studies of the chlorine-35/37 nuclides. This is largely due to the more moderate quadrupole moments of these nuclides when compared with and I. Important advances in ggjsjjyfp... 

In nuclear notation, the element symbol refers to the nucleus only, so a proton is also sometimes represented as jH.) The number of neutrons N) in a nucleus is the mass number (/ ) minus the atomic number (Z) N = A — Z. The two naturally occurring isotopes of chlorine, for example, have 17 protons (Z = 17), but one has 18 neutrons (nCl, also written Cl) and the other has 20 ( Cl, or Cl). Nuclides can also be designated with the element name followed by the mass number, for example, chlorine-35 and chlorine-37. Despite some small variations, in naturally occurring samples of an element or its compounds, the isotopes of the element are present in particular, fixed proportions. Thus, in a sample of sodium chloride (or any Cl-containing substance), 75.77% of the Cl atoms are chlorine-35 and the remaining 24.23% are chlorine-37. 

Davis R Jr, Schaeffer OA (1955) Chlorine-36 in nature. Ann NY Acad Sci 62 107-121 Desilets D, Zreda M (2001) On scaling cosmogenic nuclide production rates for altitude and latitude using cosmic ray measurements. Earth Planet Sci Lett 193 213-225 Desilets D, Zreda M, Lrfton NA (2001) Comment on Scaling factors for prodnction rates of in situ produced cosmogenic nuclides a critical reevaluation by Tibor J. Dunai. Earth Planet Sci Lett 188 283-287... 

The mass of a neutron is l.(X)8 665 u while that of the hydrogen atom is l.(K)7 825 u. Since both neutrons and protons have almost unit atomic masses, the atomic mass of a nuclide should be close to the number of nucleons, i.e. the mass number. However, when the table of elements in the periodic system (Appendix I) is studied it becomes obvious that many elements have masses which are far removed from integral values. Chlorine, for example, has an atomic mass value of 35.453 u, while copper has one of 63.54 u. These values of the atomic masses can be explained by the effect of the relative abundances of the isotopes of the elements contributing to produce the observed net mass. 

The amount of a nuclide (stable or radioactive) relative to other nuclides of the same element in a given sample. The natural abundance is the abundance of a nuclide as it occurs naturally. For instance, chlorine has two stable isotopes of masses... 

The atomic weights listed in the periodic table are relative numbers ( C = 12.0000. ..) based upon the weighted average of naturally occurring isotopes (e.g., the atomic mass of chlorine is 35.45 reflecting the roughly 3 1 ratio of Cl to Cl). The isotope Cl has 17 protons (atomic number = 17) and 18 neutrons in its nucleus C1 has 17 protons and 20 neutrons. A more precise analysis combines the relative abundances and precise relative masses of the two stable nuclides of chlorine ( Cl 75.78 percent 34.968853. Cl 24.22 percent 36.965903) as follows Relative Atomic Mass of Chlorine 0.7578 (34.968853) + 0.2422 (36.965903) = 35.45 It is noteworthy that on rare occasions, lUPAC may introduce a very slight modification to the atomic mass provided for an element in the periodic table. The relative masses of the nuclides are known to... 

The nuclide SP was found by Lindner in the spallation products of chlorine bombarded by high energy protons and by Turkevich and Samuels in neutron irradiated quartz. The beta decay energy is found to be about 100 keV, and the lifetime about 700 years. This locates the lowest T — 2 level of at an excitation of 11.23 MeV. The decay is probably to the ground state of P transition... 

Indicate whether each of the following nuclides lies within the belt of stability in Figure 21.2 (a) neon-24, (b) chlorine-32, (c) tin-108, (d) polonium-216. For any that do not, describe a nuclear decay process that would alter the neutron-to-proton ratio in the direction of increased stability. [Section 21.2]... 

Chlorine has two stable nuclides, C1 and Cl. In contrast, Cl is a radioactive nuclide that decays by beta emission, (a) What is the product of decay of Cl (b) Based on the empirical rules about nuclear stability, explain why the nucleus of Cl is less stable than either Cl or Cl. 

Chlorine-36 is a cosmogenic radioactive (i.e., unstable) nuclide that is produced by a nuclear spallation reaction in grains of metallic iron in stony meteorites. After a meteorite specimen has landed on the surface of the Earth, the production of all cosmogenic radionuclides stops and Cl decays at a rate depending on its halflife. The terrestrial age of a meteorite is calculated from the remaining concentration of Cl by an application of the law of radioactivity (Faure and Mensing 2005). 

Many elements exist as a mixture of isotopes. Figure 2.14 shows the isotopes of carbon, chlorine and hydrogen as nuclide symbols. Isotopes of the same element all have the same element symbol and atomic number. Figure 2.15 shows the three isotopes of hydrogen as Bohr diagrams. 

The rate at which a sample of a radioactive nuclide decays is expressed in terms of half-life. This quantity is the time required for half of the atoms of a sample of a given nuclide to decay. For example, it takes 37.2 min for half of the nuclei of chlorine-38 to decay to argon-38. After 37.2 min, 0.50 g of a 1.0 g sample of chlorine-38 will remain, and there will be 0.50 g of argon-38. After two half-lives (74.4 min), the fraction of chlorine-38 that remains will be 1 of 1, or... 

Earlier proposals for fast-spectrum MSRs have used chloride salts [6]. However chloride salts have three major drawbacks (1) a need for isotopically separated chlorine to avoid high-cross-section nuclides (2) the activation product Cl, which presents significant challenges to waste management because of its mobility in the environment and (3) the more corrosive characteristics of chloride systems relative to fluoride systems. 

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