Polonium spectra

Though polonium was the first of the new natural radioactive elements its symbol Po did not appear in the appropriate box in the periodic system. The atomic mass of the element was very difficult to measure. The lines of the polonium spectrum were reliably identified in 1910. It was only in 1912 that the symbol Po occupied its place in the periodic table. 

Radium is chemically similar to barium it displays a characteristic optical spectrum its salts exhibit phosphorescence in the dark, a continual evolution of heat taking place sufficient in amount to raise the temperature of 100 times its own weight of water 1°C every hour and many remarkable physical and physiological changes have been produced. Radium shows radioactivity a million times greater than an equal weight of uranium and. unlike polonium, suffers no measurable loss of radioactivity over a short period of time (its half life is 1620 years). From solutions of radium salts, there is separable a radioactive gas radium emanation, radon, which is a chemically ineit gas similai to xenon and disintegrates with a half life of 3.82 days, with the simultaneous formation of another radioactive element, Radium A (polonium-218). 

The 1,3-dioxolane ring is found in a major antifungal drug, ketoconazole (123). Ketoconazole is a broad spectrum, orally active antifungal agent and is used to treat a wide variety of superficial or deep fungal infections. Various workers, especially in Russia, have explored the use of simple oxathiolanes as radioprotectants. For example, the survival rate of mice irradiated with lethal doses of X- or -y-rays was 40% when they were pretreated with 2,2-dimethyl-l,3-oxathiolane. Other oxathiolanes were less active. 1,3-Oxathiolane, administered intravenously to dogs 2 or 3 times daily for 2-4 days before chronic irradiation with polonium-210, increased their life expectancy from 9 months to 3-7 years and alleviated radiation sickness. Some blood indicators were also restored to normal. 

The absorption spectrum of Po in HCl solutions reveals the presence of at least two complexes, A and B. Complex A absorbs with a maximum at 344m a. Complex B absorbs with a maximum at 418 m j,. The 418m a absorption can be used for the colorimetric determination of polonium. Although the 344m j, absorption is stronger in weakly acidic solutions, it is difficult to utilize because of chlorine formation brought about by radiation from the polonium. The absorbance of the complex at 344 m a was estimated by the use of a method involving the log absorbancy curves for the complex and for the chloride ion. 

In the same year the Curies, together with G. Bemont, isolated another radioactive substance for which they suggested the name radium. In order to prove that polonium and radium were in fact two new elements, large amounts of pitchblende were processed, and in 1902 M. Curie announced that she had been able to isolate about 0.1 g of pure radium chloride from more than one ton of pitchblende waste. The determination of the atomic weight of radium and the measurement of its emission spectrum provided the final proof that a new element had been isolated. 

In June 1898 a radioactive element in the bismuth precipitate was characterised and named polonium from the native country of one of us (Poland). In December 1898 a new element, named radium in the barium precipitate was announced. The still impure radium preparation had an activity a million times that of uranium. E. Demar9ay showed that radium had a characteristic spark spectrum. ... 

Curie measured the intensity of the radiation from the mineral pitchblende. The principal metal in pitchblende is uranium, but smaller quantities of many other metals are present as well. Curie found that the radioactivity of pitchblende was considerably greater than could be explained on the basis of its uranium content, and she concluded that there was an unknown and highly radioactive element present. She dissolved some pitchblende in acid and precipitated each metal in turn and checked with the electrometer to see if the radioactivity had come out of solution. She found that a high radioactivity was associated with the bismuth fraction, and named the new element which was clearly present polonium in honour of her native country. However, the spectrum of the precipitate contained no new lines, so it appeared that polonium must be present in extremely small quantity. 

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