Thallium radioactive isotopes

Thus it is evident that there are three natural radioactive isotopes of thallium, seven of lead, four of bismuth, seven elements in the polonium pleiad, three inert radioactive gases, four isotopes of radium, two of actinium, six of thorium, three eka-tantalums, and three uraniums. 

There are two stable isotopes of thallium, T1 (29.5%) and T1 (70.5%), and numerous radioactive isotopes in the mass range 184-210, there are 41 isotopes including 16 with half-lives longer than 10 minutes. 

Fifty-two radioactive isotopes of thallium have also been made. A radioactive isotope is one that breaks apart and gives off some form of radiation. Radioactive isotopes are produced when very small particles are fired at atoms. These particles stick in the atoms and make them radioactive. 

Aluminum, Aluminium. Al at. wt 26.98154 at. no. 13 valence 3. One naturally occurring isotope nAI. In addition, six radioactive isotopes and one isomer are known the most important, MAI (found in meteors), decays with emission of 0+ and >-radiation. Tw 7.4 X 10s years. One of the most abundant metals in earth s crust 8.8 % by wt occurs in nature primarily in combination with silica, also as oxide (see Aluminum Silicate Aluminum Oxide). First obtained in impure form by Oersted in 1825 prepd as metal powder by Wohler in 1827. Reviews of aluminum, its alloys and compds Brandt. Aluminum and Aluminum Alloys" in Prac. Met. Soc. Conf. Vol. 40. E. D. Verink, Ed. (Gordon Breach, New York, 1966) Aluminum. 3 Vols, K. R. Van Horn, Ed. (American Society for Metals, Metal Park, Ohio. 1967) Wade, Bannister. "Aluminum, Gallium. Indium and Thallium in Comprehensive Inorganic Chemistry, Vol, 1, J. C. Bailar, Jr. et al.. Eds. (Pergamon Press, Oxford, 1973) pp 993-1064. 

More than a hundred different radioactive isotopes have been used in medicine. Besides technetium-99m and thallium-201, other examples include iodine-131, used to measure thyroid activity phosphorus-32, used to locate tumors and iron-59, used to measure the rate of formation of red blood cells. 

Lead (13 ppm) is by far the most abundant of the heavy elements, being approached amongst these only by thallium (8.1 ppm) and uranium (2.3 ppm). This abundance is related to the fact that 3 of the 4 naturally occurring isotopes of lead (206, 207 and 208) arise primarily as the stable end products of the natural radioactive series. Only (1.4%)... 

ISOTOPES There are a total of 55 Isotopes for thallium. All are radioactive with relatively short half-lives, and only two are stable. The stable ones are Tl-203, which constitutes 29.524% of the element s existence in the Earth s crust, and Tl-205, which makes up 70.476% of the element s natural abundance found in the Earth s crust. 

A radioactive element is an element that disintegrates spontaneously with the emission of various rays and particles. Most commonly, the term denotes radioactive elements such as radium, radon (emanation), thorium, promethium, uranium, which occupy a definite place in the periodic table because of their atomic number. The term radioactive element is also applied to the various other nuclear species, (which arc produced by the disintegration of radium, uranium, etc.) including (he members of the uranium, actinium, thorium, and neptunium families of radioactive elements, which differ markedly in their stability, and are isotopes of elements from thallium (atomic number 81) to uranium (atomic number... 

The isotope 203Pb is produced by bombardment of thallium with protons in a cyclotron. The radioactive half-life is 52 h and decay is by electron capture. The associated 279-keV gamma ray enables the activity in the lung and other organs of volunteer subjects to be detected by external gamma ray spectrometers (Chamberlain etal., 1975). 

The use of cobalt radiation treatments for cancerous tumors was described in Example 26-3. Several other nuclides are used as radioactive tracers in medicine. Radioisotopes of an element have the same chemical properties as stable isotopes of the same element, so they can be used to label the presence of an element in compounds. A radiation detector can be used to follow the path of the element throughout the body. Modern computer-based techniques allow construction of an image of the area of the body where the radioisotope is concentrated. Salt solutions containing "iNa can be injected into the bloodstream to follow the flow of blood and locate obstructions in the circulatory system. Thallium-201 tends to concentrate in healthy heart tissue, whereas technetium-99 concentrates in abnormal heart tissue. The two can be used together to survey damage from heart disease. 

Cardiovascular diseases. Thallium-201 is used in the diagnosis of coronary artery disease. The isotope is administered intravenously and delivered to the heart muscle in proportion to the blood flow. Areas of restricted flow are observed as having lower levels of radioactivity, indicating some t)rpe of blockage. 

FIGURE 13.5 The uranium-238 decay series. Radium (Ra) and polonium (Po), the two elements discovered by Marie Curie, are part of this series. Radon (Rn), the radioactive gas of environmental concern, is generated as shown here wherever rocks contain uranium. Lead-206 is not radioactive. The half-lives of the isotopes in this decay series vary considerably. Uranium-238 has a half-life of 4.5 billion years, whereas the half-life of lead-210 is 22 years. Some radioactive elements, like thallium-210, have half-lives of only a few minutes. 

Both thallium 203 and 20S (70.5%) have a nuclear spin and nuclear magnetic resonance signals are detectable for these isotopes. Radioactive ° T1 is used extensively as an imaging agent in myocardial scintigraphy. 

The presence of radioactive decay products In lead sources or tracers obtained from natural sources is undesirable for some applications. A number of lead Isotopes can be produced in carrier-free form and In high yield by helium-Ion bombardment of mercury or by protnn or deuteron bombardment of thallium targets. The isotopes prepared in this way and the relevant reactions are indicated In Table I. 

---