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Topic: Radioactivity

	radioactivity. The Columbia Encyclopedia, Sixth Edition. 2001-05
		Natural radioactivity is exhibited by several elements, including radium, uranium, and other members of the actinide series, and by some isotopes of lighter elements, such as carbon-14, used in radioactive dating.
		Radioactivity may also be induced, or created artificially, by bombarding the nuclei of normally stable elements in a particle accelerator.
		The rate of disintegration of a radioactive substance is commonly designated by its half-life, which is the time required for one half of a given quantity of the substance to decay.
	www.bartleby.com /65/ra/radioact.html (1102 words)

	Learn more about Radioactivity in the online encyclopedia. (Site not responding. Last check: 2007-10-22)
		These radioactive isotopes have many important applications, including tracing biological processes in the human body for diagnosis, preserving foods in jars by killing bacteria, and dating of geological deposits based on assumptions of decay rates and isotope ratios at the time of deposit.
		Radioactive isotopes for medical use, for example, are dispensed in closed handling facilities, while nuclear reactors operate within closed systems with multiple barriers which keep the radioactive materials contained.
		The amount of radioactivity in a given sample of radioisotope is expressed by the new SI unit, the becquerel (Bq).
	www.onlineencyclopedia.org /r/ra/radioactivity.html (2010 words)

	Radioactivity
		Radioactivity refers to the particles which are emitted from nuclei as a result of nuclear instability.
		Radioactive decay rates are normally stated in terms of their half-lives, and the half-life of a given nuclear species is related to its radiation risk.
		Historically, the products of radioactivity were called alpha, beta, and gamma when it was found that they could be analyzed into three distinct species by either a magnetic field or an electric field.
	hyperphysics.phy-astr.gsu.edu /hbase/nuclear/radact.html (564 words)

	Mineral Resources: Radioactivity
		Radioactive elements are elements that contain disintegrating nuclei, emitting alpha, beta, and gamma rays.
		Radioactive minerals are often very similar in appearance, and it may be difficult to distinguish them without x-ray analysis.
		Many collectors avoid radioactive minerals because of their hazards, but if proper safeguards and precautions are followed, the dangers are minimized and even amateur collectors can collect without worry.
	www.minerals.net /resource/property/radioact.htm (393 words)

	ANSTO Information Sheet. Radioactivity, Isotopes and Radioisotopes from Nature, Nuclear Reactors and Cyclotrons for use ... (Site not responding. Last check: 2007-10-22)
		These radioactive gases seep out from rocks containing uranium and thorium to be responsible for between 50 and 80% of the background radiation exposure.
		Radioactivity had been created by disturbing the natural balance of 6 protons and 6 neutrons in the nucleus of the carbon atom with the insertion of another proton.
		As described earlier, radioactivity is the end-result from disturbing the balance between neutrons and protons in the atomic nucleus.
	www.ansto.gov.au /info/reports/radboyd.html (2882 words)

	The Hutchinson Dictionary of Science: radioactivity@ HighBeam Research (Site not responding. Last check: 2007-10-22)
		Spontaneous alteration of the nuclei of radioactive atoms, accompanied by the emission of radiation.
		It is the property exhibited by the radioactive isotopes of stable elements and all isotopes of radioactive elements, and can be either natural or induced.
		Radioactivity was first discovered in 1896, when Becquerel observed that some photographic plates, although securely wrapped up, became flened when placed near certain uranium compounds.
	www.highbeam.com /library/doc0.asp?DOCID=1P1:28915876&refid=ip_encyclopedia_hf (155 words)

	Cyberphysics - Radioactivity at A2 Level (Site not responding. Last check: 2007-10-22)
		Radioactivity at 16+ level differs from that at 14-16 level primarily in the application of mathematical interpretation that is required.
		When considering radioactive decay as represented in equations you now have to also consider particle physics and the balancing of lepton number and baryon number (from your AS syllabus!).
		When a patient is injected with a radioactive tracer the bodily functions expel the isotope from the body by natural processes such as excretion, respiration and perspiration.
	www.cyberphysics.pwp.blueyonder.co.uk /topics/physics/radioact/A2rad.htm (477 words)

	What is radioactivity ? (Site not responding. Last check: 2007-10-22)
		It is this nucleus that is transformed when a radiation is emitted by radioactivity.
		alpha radioactivity corresponds to the emission of a helium nucleus, a particularly stable structure consisting of two protons and two neutrons, called an a particle.
		radioactivity, characterised by the emission of an anti-electron or positron e+.
	www.ccr.jussieu.fr /radioactivite/english/what_is_radioactivity.htm (309 words)

	The educational encyclopedia, physics, nuclear science, radioactivity, quantum physics (Site not responding. Last check: 2007-10-22)
		Ionizing radiation and radioactivity the properties of atoms and nuclei relevant to the understanding of ionizing radiation and radioactivity.
		Radioactive dating radiometric dating is a means of determining the "age" of a mineral specimen by determining the relative amounts present of certain radioactive elements.
		Radioactive decay and radioactivity radioactive decay and radioactivity
	users.telenet.be /educypedia/education/physicsnuclear.htm (886 words)

	Radioactivity - Succeed in Physical Science
		Some applications of the characteristics of radioactivity are to determine the age of fossils, to identify certain items, and to fight cancer.
		One method to fight cancer is to implant a radioactive pellet in a cancerous tumor.
		Radioactivity can be dangerous to living beings, such that it can kill them or cause cancer.
	www.school-for-champions.com /science/radioactivity.htm (1365 words)

	AFF/NUCLEAR: NUCLEAR WEAPONS POISON THE ENVIRONMENT WITH RADIOACTIVITY
		This radioactive dust is spread by wind and rain, contaminates water and air, is taken up by plants and enters the food chain right at the bottom, and persists for thousands of years.
		However, the second form of radioactivity release is persistent radioactivity, partly from unused fuel as argued in the previous paragraph, partly from intermediate radioactive decay products of the fuel generated during the explosion, and in some part from 'induced' radioactivity generated in surrounding non-radioactive material by the immediate radioactive blast.
		The radioactive life span of many components of this dust is very long; - plutonium 239 has a 'half-life' of twenty four thousand years, meaning that it takes that long for the radioactivity output of the plutonium to come down by one-half.
	debate.uvm.edu /handbookfile/WMD2002/033.htm (815 words)

	Physics 30 - Nuclear Physics - Natural Radioactivity
		Radioactivity is the spontaneous disintegration of an unstable atomic nucleus and the emission of particles or electromagnetic radiation.
		Radioactivity is found in naturally occurring sources and in artificially produced ones.
		Understand that no exposure to radioactive emissions, for any period of time, should be regarded as being "safe" to humans or other living organisms.
	www.sasked.gov.sk.ca /docs/physics/u4a3phy.html (1000 words)

	World Nuclear Association \| Education \| Waste Management
		Delay-and-decay however is unique to radioactive waste management; it means that the waste is stored and its radioactivity is allowed to decrease naturally through decay of the radioisotopes in it.
		Radioactive wastes occur at all stages of the nuclear fuel cycle, the process of producing electricity from nuclear materials.
		The amount of radioactivity then remaining would be similar to that of the naturally-occurring uranium ore from which the fuel originated, though it would be more concentrated.
	www.world-nuclear.org /education/wast.htm (3095 words)

	Radioactivity (Site not responding. Last check: 2007-10-22)
		Radioactivity is the spontaneous disintegration of the nuclei of some of the isotopes of certain elements, with the emission of alpha (
		Radioactivity is a random process - we cannot predict which atoms in a sample of a radioactive material will decay.
		The radon isotope is itself radioactive, and its disintegration is followed by a series of disintegrations which are effectively instantaneous, finally resulting in a stable isotope of lead (atomic number 82, mass number 207).
	www.sheffcol.ac.uk /projects/access_online/Health_Science_Access/Chemistry_1/Radioactivity/radioactivity.htm (453 words)

	Natural Radioactivity
		Natural radioactivity is common in the rocks and soil that makes up our planet, in water and oceans, and in our building materials and homes.
		Radioactive elements are often called radioactive isotopes or radionuclides or just nuclides.
		Often, radionuclides are symbolized based on the element and on the atomic weight, as in the case of radioactive hydrogen or tritium with an atomic weight of 3 is shown as H-3 or
	www.physics.isu.edu /radinf/natural.htm (2866 words)

	Marie Curie (Site not responding. Last check: 2007-10-22)
		Together, they demonstrated in a major discovery that radioactivity was not the result of a chemical reaction but a property of the element or, more specifically, of the atom.
		She deduced that there were other substances besides uranium that were very radioactive, such as polonium and radium, which she discovered in 1898.
		Radioactivity is the starting point for cancer treatment, for the dating techniques used on ancient objects, rocks and the universe, and for molecular biology and modern genetics; it is also the source of nuclear energy and the atomic bomb.
	www.france.diplomatie.fr /label_france/ENGLISH/SCIENCES/CURIE/marie.html (1498 words)

	Radon and Radioactivity - Facts and Controversies
		These radioactive particles enter the food chain, ending up in fruits and berries, the flesh of fish and animals, and ultimately, in the bodies of human beings.
		Since the mid 1960's, the watch manufacturers are using Tritium, a radioactive form of hydrogen with a half-life of 12 years, or Promethium, a man-made radioactive element with a half-life of 2.6 years.
		Radioactive clouds travel hundreds of miles and after the fallout rains on grass, feeding cattle produces radioactive milk.
	www.radonseal.com /radon-facts.htm (4478 words)

	RADIOACTIVITY: HALF-LIFE (Site not responding. Last check: 2007-10-22)
		Radioactivity: Spontaneous changes in a nucleus accompanied by the emission of energy from the nucleus as a radiation.
		Radioactive Half-Life: A period of time in which half the nuclei of a species of radioactive substance would decay.
		The radioactive half-life of the substance is the period of time over which the number of radioactive nuclei decreases by a factor of one-half.
	einstein.byu.edu /~masong/HTMstuff/C24A1.html (278 words)

	Physics 30: Atomic Physics - Half-Life and Radioactive Decay
		The rate of radioactive emissions of a radioactive nuclide is directly proportional to the amount of radioactive material present.
		Recognize that the rate of radioactive decay for a given nuclide is related to the energy change that accompanies the transformation.
		Recognize that the expressed relationships for the radioactive decay are based on statistics and probability, and on the examination of the behaviour of a large number of individual situations.
	www.sasked.gov.sk.ca /docs/physics/u8b3phy.html (1434 words)

	UIC - Radiation and Life (Site not responding. Last check: 2007-10-22)
		Another source of nuclear radioactivity is when one form of a radioisotope changes into another form, or isomer, releasing a gamma ray in the process.
		After one half-life the level of radioactivity of a substance is halved, after two half-lives it is reduced to one quarter, after three half-lives to one-eighth and so on.
		Radioactive materials are therefore often stored or handled under water, or by remote control in rooms constructed of thick concrete or lined with lead.
	www.uic.com.au /ral.htm (3438 words)

	Elements and Compounds--Physical Science lesson plan (grades 6-8)--DiscoverySchool.com (Site not responding. Last check: 2007-10-22)
		Radioactivity is the property of some elements or isotopes to spontaneously emit particles of energy by the disintegration of their atomic nuclei.
		Make sure they understand that radioactivity is technically defined as the property of some elements or isotopes of spontaneously emitting particles of energy by the disintegration of their atomic nuclei.
		Definition: An intensely radioactive brilliant white metallic element that resembles barium chemically, occurs in combination in minute quantities in minerals, emits alpha particles and gamma rays to form radon, and is used chiefly in luminous materials and in the treatment of cancer.
	school.discovery.com /lessonplans/programs/elementsandcompounds (1937 words)

	Newton's Apple: Teacher's Guides: Sports Clinic; Radioactivity; Acne Chat; Tigers
		While both of these uses represent sources of radioactivity, the truth of the matter is that we are constantly being exposed to natural sources of radiation coming from everyday things like rocks, soil, water and metal.
		Radioactivity was first discovered in 1896 by Antoine Becquerel who was actually looking for sources of X-rays.
		Simply stated, radioactivity is released when the nucleus of certain elements goes through a spontaneous breakdown.
	www.ktca.org /newtons/newtonsclassics/classic6.html (1300 words)

	Radioactive decay and radioactivity
		The third class of radioactive decay is gamma decay, in which the nucleus changes from a higher-level energy state to a lower level.
		The activity of a sample of radioactive material (i.e., a bunch of unstable nuclei) is measured in disintegrations per second, the SI unit for this being the becquerel.
		Radioactivity is often used in determining how old something is; this is known as radioactive dating.
	physics.bu.edu /~duffy/PY106/Radioactivity.html (1644 words)

	The Discovery Of Radioactivity: The Dawn of the Nuclear Age
		Marie Curie, with her husband and continuing after his death, established the first quantitative standards by which the rate of radioactive emission of charged particles from elements could be measured and compared.
		In addition, she found that there was a decrease in the rate of radioactive emissions over time and that this decrease could be calculated and predicted.
		As a result, radioactive carbon atoms are not replaced as they decay, and the amount of this material decreases over time.
	www.accessexcellence.org /AE/AEC/CC/radioactivity.html (1373 words)

	radioactivity -- Encyclopædia Britannica
		Radioactivity demonstrated that the atom was neither indivisible nor immutable.
		The first observation of heavy-ion radioactivity was that of a 30-MeV, carbon-14 emission from radium-223 by H.J. Rose and G.A. Jones in 1984.
		The unit of measurement of the radioactivity of a substance is the curie.
	www.britannica.com /eb/article-9110413 (723 words)

	MedlinePlus Medical Encyclopedia: Radioactivity test
		Radioactive iodine uptake test is a type of nuclear test performed to evaluate thyroid function.
		The patient ingests radioactive iodine (I-123 or I-131) capsules or liquid.
		After a time (usually 6 and 24-hours later), a gamma probe is placed over the thyroid gland to measure the amount of radioactivity in the thyroid gland.
	www.nlm.nih.gov /medlineplus/ency/imagepages/9806.htm (156 words)

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