Calcium-47, radioactive decay

Calcium also has isotopic variations stemming from the radioactive decay of " K to " Ca. These variations can be used for geochronology and may also be useful for studies of rock weathering, soil formation, magma genesis, diagenesis, and metamorphism. 

The dominant nuclear species resulting from processes at temperatures between 4 and 6 billion k include titanium-44, chromium-48, rron-52 and 53, nickel-56 and 57 and zinc-58, 60, 61 and 62. Isotopic abundances resulting from radioactive decay of these nuclei are compatible with terrestrial and meteoritic measurements relating to calcium-44, titanium-48, chromium-52 and 53, iron-56 and 57, and nickel-58, 60, 61 and 62. 

Strontium ion, Sr 2, can replace calcium ion in bone. If a product of radioactive fallout, strontium-90, 90sr+2, js placed in bone, however, its radioactive decay will destroy both bone and surrounding tissue. 

Derivation (1) By fractional distillation of liquid air. (2) By the treatment of atmospheric nitrogen with metals such as magnesium and calcium to form nitrides. (3) Recovery from natural gas oxidation bottoms-steam in ammonia plant. (4) Originally formed by radioactive decay of K. 

During the irradiation process, reactions that involve potassium, calcium, and chlorine occur, but the only one of interest is that cited above. The number of radiogenic Ar atoms present in a sample due to the radioactive decay of potassium-40 during its geological history is given by... 

Practically no thorium, but substantial amounts or uranium are contained in calcium carbonates deposited in saline lakes and also in the oceans where they sometimes reach 5 ppm. Hence, there is almost no initial Th activity in newly deposited carbonates, hut due to the radioactive decay of the activity of Th increases with time. Consideration of this lead... 

Strontium-90, 3gSr, is a radioactive decay product of nuclear fallout from nuclear weapons testing. Because of its chemical similarity to calcium, it is incorporated into the bones if present in food. The half-life of strontium-90 is 28.1 y. What is the decay constant of this isotope What is the activity of a sample containing 5.2 ng (5.2 X 10 g) of strontium-90 ... 

The radioactive element is a silvery, shiny, soft metal that is chemically similar to calcium and barium. It is found in tiny amounts in uranium ores. Its radioactivity is a million times stronger that that of uranium. Famous history of discovery (in a shed). Initially used in cancer therapy. Fatal side effects. Small amounts are used in luminous dyes. Radium was of utmost importance for research into the atom. Today its reputation is rather shaky as its decay gives rise to the unpleasant radon (see earlier). In nuclear reactors, tiny amounts of actinium are formed from radium. 

Whatever caused this stunning blue sheen, it represented a unique opportunity to test the theory of how massive stars explode and how nucleosynthesis takes place within the explosion. This theory predicted that isotopes of mass 44, 56 and 57 would be produced by the sudden, explosive grafting of alpha particles (helium nuclei) and protons onto silicon nuclei (see Appendix 3). They would be synthesised in their radioactive forms, nickel-56, nickel-57 and titanium-44, in that order of importance (see Table 7.1). After a suitable series of decays, these sparsely scattered nuclei in the supernova debris would arrive at their stable forms, iron-56, iron-57 and calcium-44. 

Calcium polyphosphate, dissociation and chain length, 4 48 Calcyclin, 46 454-456 Californium, 20 111 availability and price, 31 2 isotopes, 2 201 melting point, 31 6 oxidation state, 2 197 physical properties, 31 36 preparation and purification, 31 5, 7, 12, 33 apparatus, 31 34, 35 purity, 31 3 radioactivity, 31 33 vapor pressure, 31 6 Califomium-252, a-decay, 31 28 Californium oxide, metallothermic reduction, 31 7, 33... 

Radium, similarly to calcium, deposits in bone within those areas where new bone mineral is being formed and also on all bone surfaces. Radium remains in those areas of new bone formation, but the radium deposits on bone surfaces eventually move into the depths of compact bone as new bone matrix is deposited on top of them. In this deposition process, short-lived radium-224 rapidly decays, leaving no radioactivity within bone whereas, long-lived radium-226 remains in the skeleton indefinitely (Rowland 1966). Mays et al. (1975) have demonstrated that the radon to radium ratio in bone increased with time after injection in beagles. 

Radioactive waste from certain nuclear power plants and from weapons testing can lead to health problems. For example, ions of the radioactive isotope strontium-90, an alkali metal, exhibit chemical behaviour similar to calcium ions. This leads to incorporation of the ions in bone tissue, sending ionizing radiation into bone marrow, and possibly causing leukemia. Given the following equation for the decay of strontium-90, how would you complete it ... 

Samples (156) were taken from 54 reference lithic pieces that represented five rock types. These samples were analyzed at the SLOWPOKE Reactor Facility of the University of Toronto. They were irradiated for 1 min at 2 kW, or for 1 or 2 min at 5 kW (depending on their radioactivity level in preliminary tests). Upon removal from the reactor, the samples, which weighed between 0.1 and 0.3 g, were left to decay for 18 min and were counted for 5 min with a Ge(Li) y-ray detector coupled to a multichannel analyzer. Trace element concentrations were calculated with the comparator method (7). The 15 elements examined were barium, titanium, sodium, aluminum, potassium, manganese, calcium, uranium, dysprosium, strontium, bromine, vanadium, chlorine, magnesium, and silicon. The first seven of these elements were the most useful in the differentiation of major rock types. 

The calcium-40 is not useful for radioactive dating because it cannot be distinguished from other calcium in the rock. The argon-40, however, can be measured. Figure 17 shows the decay of potassium-40 through four half-lives. 

As you may know, some common everyday substances are radioactive. In this lab you will investigate the three naturally occurring potassium isotopes found in a common store-bought salt substitute. Two of potassium s isotopes, potassium-39 (93.1%) and potassium-41 (6.89%) are stable. However, potassium-40 (0.01%) decays by beta emission to form stable calcium-40. You will first measure the background radiation level, and then use that information to determine the radiation due to the beta decay of potassium-40. You will also measure radiation at various locations around your school. 

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