Peter atkins chemistry pdf
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Follow the link for more information. Peter atkins chemistry pdf is a chemical element with symbol Po and atomic number 84. Polonium was discovered in 1898 by Marie and Pierre Curie, when it was extracted from uranium ore and identified solely by its strong radioactivity: it was the first element to be so discovered.
Polonium was named after Marie Curie’s homeland of Poland. 210Po is an alpha emitter that has a half-life of 138. 210Po emits about as many alpha particles per second as 5 grams of 226Ra. About one in 100,000 alpha emissions causes an excitation in the nucleus which then results in the emission of a gamma ray with a maximum energy of 803 keV. The alpha form of solid polonium. Polonium is a radioactive element that exists in two metallic allotropes. The alpha form is the only known example of a simple cubic crystal structure in a single atom basis, with an edge length of 335.
The chemistry of polonium is similar to that of tellurium, although it also shows some similarities to its neighbor bismuth due to its metallic character. Polonium dissolves readily in dilute acids but is only slightly soluble in alkalis. The most stable class of polonium compounds are polonides, which are prepared by direct reaction of two elements. Halides of the structure PoX2, PoX4 and PoF6 are known.
They are soluble in the corresponding hydrogen halides, i. Polonium has 33 known isotopes, all of which are radioactive. They have atomic masses that range from 188 to 220 u. This element was the first one discovered by the Curies while they were investigating the cause of pitchblende radioactivity.
Pitchblende, after removal of the radioactive elements uranium and thorium, was more radioactive than the uranium and thorium combined. In the United States, polonium was produced as part of the Manhattan Project’s Dayton Project during World War II. Much of the basic physics of polonium was classified until after the war. The fact that it was used as an initiator was classified until the 1960s. The Atomic Energy Commission and the Manhattan Project funded human experiments using polonium on five people at the University of Rochester between 1943 and 1947.
Polonium is a very rare element in nature because of the short half-life of all its isotopes. Because it is present in small concentrations, isolation of polonium from natural sources is a tedious process. 210 and was obtained by processing 37 tonnes of residues from radium production. In 1934, an experiment showed that when natural 209Bi is bombarded with neutrons, 210Bi is created, which then decays to 210Po via beta-minus decay.
The final purification is done pyrochemically followed by liquid-liquid extraction techniques. This process can cause problems in lead-bismuth based liquid metal cooled nuclear reactors such as those used in the Soviet Navy’s K-27. The longer-lived isotopes of polonium, 208Po and 209Po, can be formed by proton or deuteron bombardment of bismuth using a cyclotron. Other more neutron-rich and more unstable isotopes can be formed by the irradiation of platinum with carbon nuclei. Polonium-based sources of alpha particles were produced in the former Soviet Union. Such sources were applied for measuring the thickness of industrial coatings via attenuation of alpha radiation. Therefore, 210Po is used as an atomic heat source to power radioisotope thermoelectric generators via thermoelectric materials.
The alpha particles emitted by polonium can be converted to neutrons using beryllium oxide, at a rate of 93 neutrons per million alpha particles. Alpha particles emitted by polonium ionize air molecules that neutralize charges on the nearby surfaces. NRC and similar authorities as they are not considered hazardous. Polonium is highly dangerous and has no biological role. It has been reported that some microbes can methylate polonium by the action of methylcobalamin. The committed effective dose equivalent 210Po is 0.
The maximum allowable body burden for ingested 210Po is only 1. The target organs for polonium in humans are the spleen and liver. 210Po is widely used in industry, and readily available with little regulation or restriction. Polonium and its compounds must be handled in a glove box, which is further enclosed in another box, maintained at a slightly higher pressure than the glove box to prevent the radioactive materials from leaking out. Studies such as this were funded by the Manhattan Project and the AEC and conducted at the University of Rochester. The objective was to obtain data on human excretion of polonium to correlate with more extensive data from rats.
It has also been suggested that Irène Joliot-Curie was the first person to die from the radiation effects of polonium. She was accidentally exposed to polonium in 1946 when a sealed capsule of the element exploded on her laboratory bench. In 1956, she died from leukemia. A leak was discovered at a Weizmann Institute laboratory in 1957.
Traces of 210Po were found on the hands of Professor Dror Sadeh, a physicist who researched radioactive materials. The cause of death in the 2006 homicide of Alexander Litvinenko, a Russian KGB agent who had defected to the British MI6 intelligence agency, was determined to be 210Po poisoning. Abnormally high concentrations of 210Po were detected in July 2012 in clothes and personal belongings of the Palestinian leader Yasser Arafat, a heavy smoker, who died on 11 November 2004 of uncertain causes. In one experiment, rats were given a fatal dose of 1. Polonium-210 may be quantified in biological specimens by alpha particle spectrometry to confirm a diagnosis of poisoning in hospitalized patients or to provide evidence in a medicolegal death investigation. Polonium-210 is widespread in the biosphere, including in human tissues, because of its position in the uranium-238 decay chain. As early as the 1920s Antoine Lacassagne, using polonium provided by his colleague Marie Curie, showed that the element has a specific pattern of uptake in rabbit tissues, with high concentrations, particularly in liver, kidney, and testes.