Phosphorus radioactive decay

The product, phosphorus-30, is radioactive, decaying by positron emission ... 

We know that nuclear weapons are capable of mass destruction, yet radiation therapy, shown in Figure 4.18, is a proven cancer fighter. Smoke detectors, required by law in all homes, rely on the radioactive decay of americium-241. The human body itself is radioactive, due to the presence of radioactive isotopes including carbon-14, phosphorus-32, and potassium-40. Most people view radioactivity and nuclear reactions with a mixture of fascination, awe, and fear. Since radioactivity is all around us, it is important to understand what it is, how it arises, and how we can deal with it safely. 

Predict the type of radioactive decay process for the following radionuclides (a) jB, (b) fsCu, (c) phosphorus-32, (d) chlorine-39. 

Now consider the radioactive isotope phosphorus-30. You can predict the expected type of radioactive decay of this isotope by noting whether the mass number is less than or greater than the mass number of stable isotopes. Generally, the mass numbers of stable isotopes will be close to the numerical value of the atomic weight of the element. The atomic weight of phosphorus is 31.0 amu, so you might expect phosphorus-31 to be a stable isotope (which it is). Phosphorus-30 has a mass number less than that of the stable isotope phosphorus-31. Therefore, you expect that phosphorus-30 will decay by either positron emission or electron capture. Positron emission is actually observed. 

The phosphorus isotope is used in biochemical studies to determine the pathways of phosphorus atoms in living organisms. Its presence is detected through its emission of j8 particles, (a) What is the decay constant for expressed in the unit s (b) What is the activity of a 1.00 mg sample of (that is, how many atoms disintegrate per second) (c) Approximately what mass of P will remain in the original 1.00 mg sample after 57 days (See Table 25.1.) (d) What will be the rate of radioactive decay after 57 days ... 

Sometimes the nucleus can be changed by bombarding it with another type of particle. This is referred to as induced radioactivity. In 1934, Irene Curie, the daughter of Pierre and Marie Curie, and her husband, Frederic Joliot, announced the first synthesis of an artificial radioactive isotope. They bombarded a thin piece of aluminum foil with ot-particles produced by the decay of polonium and found that the aluminum target became radioactive. Chemical analysis showed that the product of this reaction was an isotope of phosphorus. 

Sodium phosphate P 32 is a radiopharmaceutical. Phosphorus is necessary to the metabolic and proliferative activity of cells. Radioactive phosphorus concentrates to a very high degree in rapidly proliferating tissue. Sodium phosphate P 32 decays by beta emission with a physical half-life of 14.3 days. The mean energy of the sodium phosphate P 32 beta particle is 695 keV. It is indicated in the treatment of polycythemia vera, chronic myelocytic leukemia, and chronic lymphocytic leukemia and skeletal metastases. 

The second reaction continued because the phosphorus-30 was decaying more slowly than it was being produced. Phosphorus-30 was the first radioactive isotope to be produced artificially. Today, more than 1000 other radioactive isotopes have been produced. 

Irene Joliot-Curie (daughter of Pierre and Marie Curie) and her husband Frederic Joliot-Curie observed that when aluminum-27 is bombarded with alpha particles, neutrons and positrons (positive electrons) are emitted as part of the products. When the source of alpha particles is removed, neutrons cease to be produced, but positrons continue to be emitted. This observation suggested that the neutrons and positrons come from two separate reactions. It also indicated that a product of the first reaction is radioactive. After further investigation, they discovered that, when aluminum-27 is bombarded with alpha particles, phosphorus-30 and neutrons are produced. Phosphorus-30 is radioactive, has a half-life of 2.5 minutes, and decays to silicon-30 with the emission of a positron. The equations for these reactions are... 

The major elements O, C, H, and N in biological materials show little or no activity following exposure to even the high neutron flux densities of the nuclear reactor, and a -y-spectrum obtained shortly after the end of irradiation is dominated by radioactive indicators of the elements K, Na, and Cl. After approximately 1 week these radioisotopes will have decayed almost completely, and except for a small amount of radioactive phosphorus the activity remaining in a biological sample is attributed to elements present at the trace level. Such long-lived indicators of trace elements invariably include the elements Fe and Zn, which often conceal the presence of radioactive indicators of other trace elements. 

In 1933, a nuclear bombardment reaction was used to produce the first artificial radioactive isotope. Irene and Frederic Joliot-Curie found that aluminum bombarded with alpha particles produces phosphorus-30, which decays by enutting positrons. The... 

A sample of a phosphorus compound contains phosphorus-32. This sample of radioactive isotope is decaying at the rate of 6.0 X 10 disintegrations per second. How many grams of are in the sample The half-life of P is 14.3 d. 

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