Pitchblende polonium from

The name comes from the Latin Polonia, meaning Poland, the home country of Marie Curie, one of its discoverers. It was discovered by Marie Curie (1867-1934) and Pierre Curie (1859-1906) in 1898 when they were studying uranium and other radioactive materials found in pitchblende. Polonium is very rare, and, although some exists naturally, most polonium is manufactured in nuclear reactors. Polonium is very dangerous even in minute quantities because of its level of radioactivity. It is a very good source of alpha radiation and, if combined with beryllium, produces neutrons. It is thus used as a thermoelectric source for specialized applications such as satellites. 

Marchwald obtained 3 milligrams of polonium from 15 tons of pitchblende. 

Poland, native country of Mme. Curie) Polonium, also called Radium F, was the first element discovered by Mme. Curie in 1898 while seeking the cause of radioactivity of pitchblend from Joachimsthal, Bohemia. The electroscope showed it separating with bismuth. 

One curious observation, however, was that pure U actually had a lower radioactivity than natural U compounds. To investigate this. Curie synthesized one of these compounds from pure reagents and found that the synthetic compound had a lower radioactivity than the identical natural example. This led her to believe that there was an impurity in the natural compound which was more radioactive than U (Curie 1898). Since she had already tested all the other elements, this impurity seemed to be a new element. In fact, it turned out to be two new elements—polonium and radium— which the Curies were successfully able to isolate from pitchblende (Curie and Curie 1898 Curie et al. 1898). For radium, the presence of a new element was confirmed by the observation of new spectral lines not attributable to any other element. This caused a considerable stir and the curious new elements, together with their discoverers, achieved rapid public fame. The Curies were duly awarded the 1903 Nobel prize in Physics for studies into radiation phenomena, along with Becquerel for his discovery of spontaneous radioactivity. Marie Curie would, in 1911, also be awarded the Nobel prize in chemistry for her part in the discovery of Ra and Po. 

Marie (NLP 1903, NLC 1911 ) and Pierre (NLP 1903 ) Curie took up further study of Becquerel s discovery. In their studies, they made use of instrumental apparatus, designed by Pierre Curie and his brother, to measure the uranium emanations based on the fact that these emanations turn air into a conductor of electricity. In 1898, they tested an ore named pitchblende from which the element uranium was extracted and found that the electric current produced by the pitchblende in their measuring instrument was much stronger than that produced by pure uranium. They then undertook the herculean task of isolating demonstrable amounts of two new radioactive elements, polonium and radium, from the pitchblende. In their publications, they first introduced the term radio-activity to describe the phenomenon originally discovered by Becquerel. After P. Curie s early death, M. Curie did recognize that radioactive decay (radioactivity) is an atomic property. Further understanding of radioactivity awaited the contributions of E. Rutherford. 

Marie Sklodowska Curie (1867—1934) and Pierre Curie (1859—1906) are credited with discovering polonium as they sought the source of radiation in pitchblende after they removed the uranium from its ore. Their discovery in 1898 led to the modern concepts of the nucleus of the atom, its structure, and how it reacts. 

Polonium can be recovered from natural pitchblende. The yield, however, is exceedingly small as 1 g of polonium is contained in about 25,000 tons of pitchblende. The element may be isolated from the pitchblende extract by deposition on a bismuth plate immersed in chloride solution. 

Polonium can be produced from other sources, too, that offer much higher yield than pitchblende. Two such processes are as follows ... 

Pierre and Marie Curie called Becquerel s radiation radioactivity . They found that another heavy element, thorium, was also radioactive, and deduced that natural uranium ore (pitchblende) contained other radioactive elements, which they called polonium (after Marie s native country) and radium (because it glowed). After two years of sifting through tonnes of uranium ore, they isolated salts of these new elements. The work left both the Curies with hands badly scarred from radiation bums, and it no doubt hastened Marie s death from leukaemia in 1934. Pierre might have met the same fate had he not been tragically killed in a road accident in 1906. 

Presently. 24 isotopes of actinium, with mass numbers ranging from 207 to 2.30, have been identified. All are radioactive. One year after the discovery of polonium and radinm by the Curies, A. Debierne found an unidentified radioactive substance in the residue after treatment of pitchblende. Debierne named the new material actinium after the Greek word for ray. F. Giesel, independently in 1902, also found a radioactive material in the rare-earth extracts of pitchblende. He named... 

At the end of long and hard days, they isolated a new element. From pitchblende , an uranium ore, they obtained a new element which radiates rays similar to uranium. They named this new element polonium to honor the memory of Poland, Marie Curie s homeland. This discovery led to the discovery of radium which made the Curies famous. With the discoveries of these new radioactive elements, the number of such elements reached four. They were uranium, thorium, polonium and radium. 

The total number of publications that describes organometallic chemistry of polonium makes up one of the smallest segments of chemical literatme. The element is very rare its natural concentration in pitchblende ores is only about 0.1 mg per ton. Twenty-one isotopes are known, all of which are radioactive. Of these, °Po is most commonly used for chemical purposes because it can be synthesized in milhgram amounts from g Bi by an (n,y) reaction. The gg Bi undergoes /3-decay (5.0 days) to produce g4°Po. This isotope has a half-life of about 138 days. Although the isotopes 209pQ... 

Natural radioactivity. Discovery by Becquerel, Isolation of polonium and radium from pitchblende, by the Curies. Alpha rays, beta rays, gamma rays. Effect of a magnetic field on these rays. Use of radium and other radioactive elements in the treatment of cancer. 

Curie, Marie S. (1867-1934). Born in Warsaw, Poland, she and her husband Pierre made an intensive study of the radioactive properties of uranium. They isolated polonium in 1898 from pitchblende ore. By devising a tedious and painstaking separation method, they obtained a salt of radium in 1912, receiving the Nobel Prize in physics for this achievement in 1903 jointly with Becquerel. In 1911, Mme. Curie alone received the Nobel Prize in chemistry. Her work laid the foundation of the study of radioactive elements which culminated in control of nuclear fission. 

Marie and Pierre Curie heard that the element uranium gives off radiation. Uranium comes from an ore, which is a type of rock called pitchblende. They found two other radioactive elements in the pitchblende. They were polonium and radium. 

From this mineral it was formerly customary to extract the uranium and discard the residue. The chemical study of such a complex mixture is an exceedingly difficult task, but by patient effort M. and Mme. Curie succeeded > in 1898 in separating two new radioactive substances to which the names radium and polonium were applied. The latter is now commonly called radium F. Later Debieme discovered 2 a third radioactive constituent of pitchblende residues and named the new substance actinium. 

The method of treatment consisted in effecting a concentration of some of the constituents of the residues and observing the radioactivity of the various portions into which the material was divided. It was observed that if barium was concentrated the radioactivity of that portion increased rapidly. From a ton of residues there may be prepared 10-20 kilograms of crude sulfate whose activity is about 60 times that of uranium. The Curies then converted the sulfates to chlorides and subjected the material to the process of fractional crystallization. After a number of crystallizations there was obtained in the most insoluble portion a fraction, of a gram of radium chloride which was a million times as active as uranium, One ton of pitchblende is said to contain 0.37 gram of radium, 0.00004 gram of polonium,1 and a small amount of aetinium. 

Polonium is a silver-grey, radioactive metal. Discovered by chemist Marie Curie in 1898, polonium was named after her country of origin (Poland). Curie discovered the element while analyzing samples of pitchblende, or uranium ore, from Bohemia. She found that unrefined pitchblende was more radioactive than the uranium extracted from it. Small amounts of polonium and another radioactive element, radium, were later obtained from the refined ore. 

By 1898 Madame Curie and her husband Pierre, in collaboration with Bequerel, had isolated two new elements from the radioactive decay of uranium in pitchblende ore. Both were more radioactive than uranium itself. They named the first element polonium (Po) after Madame Curie s native land (Poland), and the second was named radium (Ra). Isolation of these two elements required chemical separation of very small amounts of Po and Ra from tons of pitchblende. Radium was found to be over 300,000 times more radioactive than uranium. 

Polonium occurs in U and Th minerals as a product of radioactive decay series. It was first isolated from pitchblende which contains less than 0.1 mg of Po per ton. The most accessible isotope is 210Po (a, 138.4d) obtained in gram quantities by irradiation of bismuth in nuclear reactors ... 

Radioactivity is emitted from atomic nuclei that are unstable and spontaneously change their structure. In 1896, Henri Becquerel first discovered radioactivity when he placed a piece of zinc uranyl sulfate wrapped in paper on a photographic plate. Two years later, Marie and Pierre Curie discovered two highly radioactive elements, polonium and radium, in pitchblende. a particles, the nuclei of helium atoms, were among the radiations emitted by these substances which were spontaneously transmuting. Indeed, since the earth had billions of years ago lost its original complement of light, inert helium, all helium in our... 

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. 

Pioneering work in radioactivity was carried out by the husband and wife team of Pierre and Marie Curie, who (in 1898) extracted the elements polonium and radium from an ore called pitchblende. The harmfijl effects of nuclear radiation were then unknown, and even today their laboratory notebooks remain dangerously radioactive. 

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