Lesson_5.2a_Printable_PPT

Lesson_5.2a_Printable_PPT - Natural Radioactivity Atoms...

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Natural Radioactivity Atoms with too many neutrons, or not quite enough, can sometimes exist for a while, but they're unstable. All the elements beyond bismuth (Z = 83) are unstable. Unstable atoms are radioactive: their nuclei change or decay by spitting out radiation, in the form of particles or electromagnetic waves. adioactivity is the spontaneous emission Radioactivity is the spontaneous emission of particles or energy from an atomic nucleus as it disintegrates into nucleus of another element to achieve stability. Radioactivity was discovered by Becquerel while experimenting with x- rays and photographic plates.
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Discovery of Radioactivity In March of 1896, during a time of overcast weather, Becquerel found he couldn't use the sun as an initiating energy source for his experiments. He put his wrapped photographic plates away in a darkened drawer, along with some crystals containing uranium. Much to his surprise, the plates were exposed during storage by invisible emanations from the uranium. The emanations did not require the presence of an initiating energy source-- the crystals emitted rays on their own! Later, Becquerel demonstrated that the radiation emitted by uranium shared certain characteristics with X rays but, unlike X rays, could be deflected by a magnetic field and therefore must consist of charged particles. For his discovery of radioactivity, Becquerel was awarded the 1903 Nobel Prize for physics.
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Working in the Becquerel lab, Marie Curie and her husband, Pierre, began what became a life long study of radioactivity. Marie Curie wrote, "The subject seemed to us very attractive and all the more so because the question was entirely new and nothing yet ad been written upon it." had been written upon it." She is best known as the discoverer of the radioactive elements polonium and radium and as the first person to win two Nobel prizes.
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Lesson_5.2a_Printable_PPT - Natural Radioactivity Atoms...

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