Reactions with polonium

The physical properties of the metal (Table II) resemble those of thallium, lead and bismuth, its neighbors in the Periodic Table, rather than those of tellurium, its lower homologue. The low melting and boiling points are particularly noteworthy an attempted study of the Hall effect in polonium metal has also been reported (90). In chemical properties the metal is very similar to tellurium, the most striking resemblance being in its reactions with concentrated sulfuric acid (or sulfur trioxide) and with concentrated selenic acid. The products are the bright red solids, PoSOs and... 

One convenient source of neutrons is the reaction of an alpha particle from an emitter such as polonium ( °Po) with an atom of beryllium ( Be). Write nuclear equations for the reactions that occur. 

The reactions of polonium vapour with both Main-group and Transition-group IV elements have been studied. Polonium vapour did not react with Si, Ta, or Zr carbides, but did react with tin at 370 °C to give a tin polonide, which dissociated at 670 °C to the elements. 

The nuclide gCf emits neutrons through spontaneous fission in 3% of all decays, the rest being a-decays. All the other neutron sources listed involve a radioactive nuclide whose decay causes a nuclear reaction in a secondary substance which produces neutrons. For example, ffSb produces neutrons in beryllium powder or metal as a result of the initial emission of 7-rays, in which case there is no coulomb barrier to penetrate. Radium, polonium, plutonium, and americium produce neutrons by nuclear reactions induced in beryllium by the a-particles from their radioactive decay. For the neutrons produced either by spontaneous fission in californium or by the a-particle reaction with beryllium, the... 

Rutherfordium (Z = 104) cannot be produced directly in " Ca-induced reactions, as it would require a polonium target. The isotopes Rf (Jin. — 160 s) and Rf Ty2 — 1.3 h) are the terminating SF activities of the decay chains derived from and Fl, produced in " Pu(" Ca,xn) reactions with x = 5 and X = 3, respectively [8, 316, 353]. Rf activities produced in hot-fusion reactions with lighter heavy ions with much higher cross sections are generally more appropriate for radiochemical experiments (see Liquid-Phase Chemistry of Superheavy Elements and Gas-Phase Chemistry of Superheavy Elements ). However, the long half-life of Rf may provide the means for previously unexplored radiochemical investigations. 

Polonium is found only in trace amounts in the Earths crust. In nature it is found in pitchblende (uranium ore) as a decay product of uranium. Because it is so scarce, it is usually artificially produced by bombarding bismuth-209 with neutrons in a nuclear (atomic) reactor, resulting in bismuth-210, which has a half-hfe of five days. Bi-210 subsequently decays into Po-210 through beta decay The reaction for this process is Bi( ) Bi — °Po + (3-. Only small commercial milligram amounts are produced by this procedure. 

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. 

Evidence for the existence of PoS is much stronger. Aqueous solutions in HCl containing Po and Po yield a precipitate of PoS. During the course of this reaction, Po is reduced to Po with the concurrent oxidation of sulfide to free sulfur. The same sulfide can be prepared by the reaction between polonium hydroxide and ammonium sulfide. The compound has not been successfully prepared by the direct reaction between the elements. 

Evidence for the existence of Po(S04)2 is stronger. The reaction between PoCLt or the hydroxide of polonium with sulfuric acid (0.5-5.0 N) yields a white solid identified as the hydrated solid. The solubility of this material increases with increasing acid concentration, which suggests the formation of anionic sulfate complexes. The white solid loses its water of hydration thermally and leaves a purple solid identified as the anhydrous sulfate. 

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