Polonium constants

Since the activity of polonium in time disappears completely, and since the ratio of lead to uranium is almost constant in all primary uranium minerals from a given geological formation, the last stage in the... 

Early trace level work 52) with polonium suggested the presence of the hexachloropolonite (PoCh ) ion in hydrochloric acid solution more, recent work (9) with wcighable amounts of polonium indicates that the equilibrium constant for Po4+ + 6Cl- PoCl6— is about 1014. The molar absorbancy... 

The correct answer is (C). Beta decay occurs when a neutron breaks down to form a proton and a beta particle (electron). This will cause the atomic number to increase by one, and the mass number remains constant. In the first beta decay, lead-214 becomes bismuth-214. The second beta decay converts bismuth-214 to polonium-214,... 

The average ionic charge of polonium species in chloride solutions was measured using an anion-exchange method. The method is based on measurements of the distribution ratio of polonium at a constant internal chloride ion concentration of the anion-exchanger phase. At TOM hydrochloric acid or sodium chloride solutions at pH of 1.0, tracer concentration of Po(IV) exist in the amionic forms [PoCLi(OH)] and [PoCl4(OH)2].-2... 

Actually, all elements heavier than lead and bismuth are radioactive and are constantly disintegrating. Eventually, lead and bismuth will be the heaviest natural elements on earth, for the heavier elements—polonium, radon, radium, actinium, thorium, protactinium, and uranium—will have disappeared at some date in the distant future. 

Table 6.8 gives stability constants for the complexes [FeX] and [HgX] for different halide ions while the stabilities of the Fe complexes decrease in the order F > CP > Br, those of the Hg complexes increase in the order F < CP < Br < P. More generally, in examinations of stability constants by Ahrland, Chatt and Davies, and by Schwarzenbach, the same sequence as for Fe + was observed for the lighter s- and /i-block cations, other early J-block metal cations, and lanthanoid and actinoid metal cations. These cations were collectively termed class (a) cations. The same sequence as for Hg complexes was observed for halide complexes of the later J-block metal ions, tellurium, polonium and thallium. These ions were collectively called class (b) cations. Similar patterns were found for other donor atoms ligands with O- and iV-donors form more stable complexes with class (a) cations, while those with S- and F-donors form more stable complexes with class (b) cations. 

It is interesting to note the compound HTel5-2oxin-10H2O, which has been reported to be isolated from a solution of oxine in hydroiodic acid containing teDurium. The instability constants for some tellurium halo complexes and the polonium iodo complexes including the POIf species, have been reported. 

Very soon after the radioactivity of thorium and uranium had been discovered it was found that pure samples of both of these elements were only very weakly radioactive. However, such pure samples became more and more radioactive with time until they reached a steady level identical to that in the original samples before pmification. This suggested that the uranium or thorium atoms were transforming or decaying into other radioactive daughter elements and that hitherto undiscovered series of such elements might exist. The search for the radioactive products of uranium by Marie and Pierre Curie led to the characterisation of two new elements, which were named polonium, Po, and radium, Ra. Both elements are far more radioactive than uranium and decay so rapidly that no ore deposits are formed. They exist only because they are formed constantly from naturally occurring uranium. 

The half-lives (hence the rate constants) of radioactive isotopes vary greatly from isotope to isotope. Two extreme cases fisted in Table 17.3, for example, are uranium-238 and polonium-214 ... 

The half-life of the uranium isotope is about 1 X 10 times larger than the half-life of the polonium isotope. Unlike the rate constants for chemical reactions, moreover, the rate constants for nuclear decay are unaffected by changes in environmental conditions, such as temperature and pressure (see Table 17.1). 

Estimation of Radioactivity.— The 8-ray activity of the lead used indicates that it contains in about 2 parts so-called radium G and 1 part lead, an amount of radium D of the order of 10 parts. This is betrayed by the steady growth of a penetrating jS-ray product (RaE) which comes to practical equilibrium with its parent in about a month after they are separated. Evidently the ionization— if the a-rajre from the polonium present are cut off—caused by a weighed amount of the material imder constant conditions, is a measure of the concentration of radium D relative to its isotopes radimn G and lead. Thus the determination of the activity of the end fractions gives information as to the relation between the solubility of the nitrate of radium D and the mean solubility of the nitrates of radium G and ordinary lead, a relation of great interest because it cannot be tested by atomic weight determinations. This case should afford an especially favorable test of the theory of complete identity. 

Even though some of the daughters in natural radioactive decay schemes have very short half-lives, all are present because they are constantly forming as well as decaying. It is likely that only about one gram of radium-226 was present in several tons of uraniiun ore processed by Marie Curie in her discovery of radium in 1898. Nevertheless, she was successful in isolating it. The ore also contained only a fraction of a milligram of polonium, which she was able to detect but not isolate. 

---