Radioactivity - Revision history

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	[[Category:Done ~~2015~~-09-06]]		[[Category:Done 2020-02-29]]
	[[File:radioact.gif\|400px\|framed\|right\|Figure 1. A diagram showing the repulsive Coulomb force within the nucleus along with the attractive strong force. Additionally, three forms of radioactive decay are shown.<ref name="RE1"/>]]		[[File:radioact.gif\|400px\|framed\|right\|Figure 1. A diagram showing the repulsive Coulomb force within the nucleus along with the attractive strong force. Additionally, three forms of radioactive decay are shown.<ref name="RE1"/>]]

	<onlyinclude>'''Radioactivity''' is ~~a property~~ of certain [[element]]s - such as [[uranium]] - of emitting [[energy]] in the form of [[radiation]] ~~as a result of some sort of~~ [[nuclear decay]] of an unstable [[~~atom~~]].<ref name="RE3">NRC Glossary. (July 8, 2015). ''Radioactivity'' [Online]. Available: http://www.nrc.gov/reading-rm/basic-ref/glossary/radioactivity.html</ref> ~~Nuclei~~ that exhibit radioactivity are known as '''radioactive nuclei'''. Additionally, radioactivity or simply activity can be used as a measurement to describe how many decays a [[radioactive]] atom goes through in a period of time.</onlyinclude><ref name=NRC/> These decays result in an ejection of [[particle]]s from the nucleus ~~as it changes form and obtains a greater nuclear stability~~. Radioactivity can also be referred to as '''radioactive decay''' or '''nuclear decay'''.		<onlyinclude>'''Radioactivity''' is the physical phenomenon of certain [[element]]s - such as [[uranium]] - of emitting [[energy]] in the form of [[radiation]]. This energy comes from the [[nuclear decay\|decay]] of an unstable [[nucleus]].<ref name="RE3">NRC Glossary. (July 8, 2015). ''Radioactivity'' [Online]. Available: http://www.nrc.gov/reading-rm/basic-ref/glossary/radioactivity.html</ref> Any [[nuclear species]] (particular configuration of protons, neutrons and energy) that exhibit radioactivity are known as '''radioactive nuclei'''. Additionally, radioactivity or simply activity can be used as a measurement to describe how many decays a [[radioactive]] atom goes through in a period of time.</onlyinclude><ref name=NRC/> These decays result in an ejection of energy and [[particle]]s from the nucleus. Radioactivity can also be referred to as '''radioactive decay''' or '''nuclear decay'''.

	The most common forms of radiation include [[alpha decay\|alpha]], [[beta decay\|beta]], and [[gamma decay\|gamma]] radiation, but other types of radioactive decay exist such as [[proton emission]] or [[neutron emission]], or [[spontaneous fission]] of large [[nuclei]].<ref name="RE2">US EPA, Berkeley Lab. (July 7, 2015). ''Radioactivity'' [Online]. Available: http://www2.lbl.gov/abc/wallchart/chapters/03/0.html</ref>		The most common forms of radiation include [[alpha decay\|alpha]], [[beta decay\|beta]], and [[gamma decay\|gamma]] radiation, but other types of radioactive decay exist such as [[proton emission]] or [[neutron emission]], or [[spontaneous fission]] of large [[nuclei]].<ref name="RE2">US EPA, Berkeley Lab. (July 7, 2015). ''Radioactivity'' [Online]. Available: http://www2.lbl.gov/abc/wallchart/chapters/03/0.html</ref>

	~~The radioactivity of elements can be used in~~ a number of different applications~~, such as~~ in [[medical isotope\|medicine]] and these elements act as the [[fuel]] in [[nuclear power plant]]s to [[electricity generation\|generate electricity]]. As well, the radiation from these elements can be used to [[irradiate food]]s and keep them from spoiling.		Radioactivity has a number of different applications in [[medical isotope\|medicine]] and industry. Radioactivity is even used in [[smoke alarm]]s (see [[isotopes for society\|here]] for more). Additionally, these radioactive elements act as the [[fuel]] in [[nuclear power plant]]s to [[electricity generation\|generate electricity]]. As well, the radiation from these elements can be used to [[irradiate food]]s and keep them from spoiling. To learn more about uses for radioactivity of elements, see [[isotopes for society]].

	==What Causes Radioactivity?==		==What Causes Radioactivity?==
	~~Whether or not~~ a nuclide is ~~radioactive has to do mainly with~~ its nuclear stability. ~~Nuclear~~ [[isotope]]s ~~that are unstable~~ emit radiation as a result of the conflict in the strength of the repulsive [[Coulomb force]] between [[proton]]s in the nucleus and the attractive [[strong nuclear force]] between nucleons.<ref name="RE1">HyperPhysics. (July 7, 2015). ''Radioactivity'' [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radact.html#c1</ref> If the Coulomb [[force]] and strong nuclear force do not balance, the nuclide in question lays outside the '''belt of stability''' and is radioactive. A number known as the '''neutron-to-proton ratio''' or '''N/Z ratio''' can be used to quickly see if the [[Coulomb]] force and strong nuclear force remain fairly balanced or out of balance.<ref name=book>Jeff C. Bryan. Introduction to Nuclear Science, 1st ed. Boca Raton, FL, U.S.A: CRC Press, 2009.</ref> For smaller elements near the top of the periodic table, the ratio for stability is nearly 1:1. As the nuclei get larger, the N/Z ratio increases slightly for stability.<ref name=book/> If a nucleus has too many protons or neutrons, it will likely undergo some sort of [[transmutation]] to reach a more stable state (where it changes to some new nuclide with a "better" N/Z ratio).<ref name=book/>		The stability of a [[nuclear species]] (also called a [[nuclide]]) is determined by forces within the nucleus. These forces determine its nuclear stability. Unstable nuclear [[isotope]]s emit radiation as a result of the conflict in the strength of the repulsive [[Coulomb force]] between [[proton]]s in the nucleus and the attractive [[strong nuclear force]] between nucleons.<ref name="RE1">HyperPhysics. (July 7, 2015). ''Radioactivity'' [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radact.html#c1</ref> If the Coulomb [[force]] and strong nuclear force do not balance, the nuclide in question lays outside the '''belt of stability''' and is radioactive. A number known as the '''neutron-to-proton ratio''' or '''N/Z ratio''' can be used to quickly see if the [[Coulomb]] force and strong nuclear force remain fairly balanced or out of balance.<ref name=book>Jeff C. Bryan. Introduction to Nuclear Science, 1st ed. Boca Raton, FL, U.S.A: CRC Press, 2009.</ref> For smaller elements near the top of the periodic table, the ratio for stability is nearly 1:1. As the nuclei get larger, the N/Z ratio increases slightly for stability.<ref name=book/> If a nucleus has too many protons or neutrons, it will likely undergo some sort of [[transmutation]] to reach a more stable state (where it changes to some new nuclide with a "better" N/Z ratio).<ref name=book/>

	There are ~~also more~~ complex ~~ways to decide~~ whether or not a ~~nucleus will exhibit radioactivity~~. For example, if a ~~nucleus~~ has either an odd number of protons or an odd number of neutrons, it ~~tends~~ to be radioactive ~~regardless of whether or not~~ the ~~Coulomb and strong nuclear forces balance. The reason for a~~ greater instability ~~in nuclei with odd numbers of neutrons or protons is essentially because~~ protons and neutrons like to "pair up" with particles of the same type, boosting stability.<ref name=book/> ~~As well, there is something special about having certain~~ numbers of protons or neutrons in a nucleus that promote stability. These numbers are known as [[magic number]]s.		There are many complex factors that determine whether or not a nuclide be radioactive. For example, if a nuclide has either an odd number of protons or an odd number of neutrons, it is more likely to be radioactive. If both are odd, the nuclide is almost certainly radioactive! This greater instability comes from a desire for protons and neutrons like to "pair up" with particles of the same type, boosting stability.<ref name=book/> (Of the thousands of nuclides that have been investigated only 4 stable odd-odd nuclei have been found.) Some numbers of protons or neutrons in a nucleus that promote stability. These numbers are known as [[magic number]]s.

	Most ~~radioactive [[isotope]]s~~ tend to be ~~large~~, and the last completely stable ~~nucleus~~ is bismuth (which has 83 protons). These large radioactive elements ~~tend to~~ undergo alpha decay as it quickly lowers the number of protons and [[neutron]]s in the nucleus.<ref name=book/> Most ~~nuclei that are~~ found in nature are not radioactive, because all of the short-lived radioactive nuclei have already decayed, leaving a vast majority of stable nuclei. There are only 50 naturally ~~occuring isotopes~~ that exhibit radioactivity while there are around 270 stable ~~isotopes~~.<ref name="RE2"/> ~~Hundreds~~ of short-lived ~~isotopes~~ have been created in laboratories and particle accelerators.		Most large nuclides tend to be radioactive, and the last completely stable nuclide is bismuth (which has 83 protons). These large radioactive elements often undergo alpha decay as it quickly lowers the number of protons and [[neutron]]s in the nucleus.<ref name=book/> Most nuclides found in nature are not radioactive, because all of the short-lived radioactive nuclei have already decayed, leaving a vast majority of stable nuclei. There are only 50 naturally occurring nuclides that exhibit radioactivity while there are around 270 stable nuclides.<ref name="RE2"/> Thousands of short-lived nuclides have been created in laboratories and particle accelerators.

			To explore this topic further, visit [https://energyeducation.ca/simulations/nuclear/nuclidechart.html Energy Education's Interactive Chart of Nuclides].

	==Measuring Radioactivity==		==Measuring Radioactivity==
	Radioactivity can also be used to describe how much [[ionizing radiation]] is released by a radioactive material.<ref name=NRC>NRC. (July 8, 2015). ''Measuring Radiation'' [Online]. Available: http://www.nrc.gov/about-nrc/radiation/health-effects/measuring-radiation.html</ref> The SI [[units\|unit]] of radioactivity is the [[becquerel]] (Bq), equal to one decay per second. The [[curie]] (Ci) was the original unit for radioactivity and is equal to 3.7×10<sup>10</sup> Bq.<ref name="RE3"/> [[Geiger counter]]s can be used to measure the radioactivity of a substance and these devices are widely known for the "clicking" noise they make when they detect a decay producing ionizing radiation.		Radioactivity can also be used to describe how much [[ionizing radiation]] is released by a radioactive material.<ref name=NRC>NRC. (July 8, 2015). ''Measuring Radiation'' [Online]. Available: http://www.nrc.gov/about-nrc/radiation/health-effects/measuring-radiation.html</ref> The SI [[units\|unit]] of radioactivity is the [[becquerel]] (Bq), equal to one decay per second. The [[curie]] (Ci) was the original unit for radioactivity and is equal to 3.7×10<sup>10</sup> Bq.<ref name="RE3"/> [[Geiger counter]]s can be used to measure the radioactivity of a substance and these devices are widely known for the "clicking" noise they make when they detect a decay producing ionizing radiation.

	Another way to measure how radioactive something is is to investigate its [[half-life]], since the half-life of ~~an isotope~~ is related to its radiation risk.		Another way to measure how radioactive something is is to investigate its [[half life]], since the half life of a nuclide is related to its radiation risk.

	==Safety==		==Safety==
	One common misconception about radioactivity is that ''any'' radioactive object is harmful to human health. This is not the case, however, as small doses radiation ~~are~~ not harmful to humans. In fact, there are many radioactive products that can be purchased and pose no health threats to humans. Bananas, smoke detectors, some ceramic dishware, cat litter, beer, and brazil nuts are all radioactive.<ref> Anne Marie Helmenstine. (July 7, 2015). ''10 Radioactive Everyday Objects'' [Online]. Available: http://chemistry.about.com/od/nucleardecay/ss/10-Radioactive-Products-Everyday-Items-That-Emit-Radiation.htm#showall</ref>		One common misconception about radioactivity is that ''any'' radioactive object is harmful to human health. This is not the case, however, as small doses of radiation have not been proven to be harmful to humans. In fact, there are many radioactive products that can be purchased and pose no health threats to humans. Bananas, smoke detectors, some ceramic dishware, cat litter, beer, and brazil nuts are all radioactive.<ref> Anne Marie Helmenstine. (July 7, 2015). ''10 Radioactive Everyday Objects'' [Online]. Available: http://chemistry.about.com/od/nucleardecay/ss/10-Radioactive-Products-Everyday-Items-That-Emit-Radiation.htm#showall</ref>

			However, in larger doses radiation does have negative effects on health. When radioactive materials decay, they produce '''[[ionizing radiation]]'''. Simply put, this type of radiation can strip [[electron]]s away from atoms or break [[chemical]] bonds (to make [[ion]]s). This causes damage to living tissues that cannot always be repaired.<ref name="RE8">US EPA. (July 8, 2015). ''Health Effects: Radiation'' [Online]. Available: http://www.epa.gov/radiation/understand/health_effects.html#q1</ref> Chronic exposure to radiation can lead to cancer (as a result of damage at the cellular or molecular level) or other mutations that can be harmful to fetuses. Effects from acute exposure to radiation appear quickly, and include burns and radiation poisoning. The symptoms of radiation poisoning include nausea, weakness, hair loss, and diminished organ function and this radiation sickness can result in death if the dose is high enough.<ref name="RE2"/>

	~~However~~, in ~~larger doses radiation does have negative effects on health~~. ~~When radioactive materials decay~~, ~~they produce '''[[ionizing radiation]]'''. Simply put, this type~~ of ~~radiation can strip~~ [[~~electron~~]]~~s away from atoms or break [[chemical]] bonds~~ (~~to make [[ion]]s~~). ~~This causes damage~~ to ~~living tissues that cannot always be repaired~~.~~<ref name="RE2">US EPA~~. ~~(July 8~~, ~~2015). ''Health Effects: Radiation'' [Online]. Available: http://www.epa.gov/radiation/understand/health_effects.html#q1</ref> Chronic exposure to radiation can lead to cancer (as a result~~ of ~~damage at~~ the ~~cellular or molecular level) or other mutations that can be harmful to fetuses. Effects from acute exposure to radiation appear quickly~~, ~~and include burns and radiation poisoning~~. ~~The symptoms of radiation poisoning include nausea, weakness~~, ~~hair loss, and diminished organ function~~ and ~~this radiation sickness can result in death if~~ the ~~dose~~ is ~~high enough~~.~~<ref name="RE2"/>~~		As well, some radiation is only harmful in certain circumstances. For example, smoke detectors generally contain a source of alpha particles known as [[americium]] (which is radioactive). The americium is used to detect the smoke. In the smoke detector itself, this source is radioactive but not harmful. However, because of the nature of alpha particles, the Americium is very dangerous if ingested. Smoke detectors save many lives every year, and changing the [[battery\|batteries]] once a year is a good idea. Dissecting smoke detectors however can be dangerous.

	~~As well, some radiation is only harmful in certain circumstances.~~ For ~~example, smoke detectors generally contain~~ a source of alpha particles known as americium (which is radioactive). The americium is used to detect the smoke. In the smoke detector itself, this source is radioactive but not harmful. However, because of the nature of alpha particles, the Americium is very dangerous if ingested. Smoke detectors save many lives every year, and changing the [[~~batteries~~]] ~~once a year is a good idea. Dissecting smoke detectors however can be dangerous.~~		==For Further Reading==
			*[[Linear no-threshold model]]
			*[[Isotope]]
			*[[Isotone]]
			*[[Nuclide]]
			*[[Nuclear isomer]]
			*[[Strong force]]
			*Or explore a [[Special:Random\|random page]]

	==References==		==References==
	{{reflist}}		{{reflist}}
	[[Category:Uploaded]]		[[Category:Uploaded]]

J.williams: 1 revision imported

2015-09-18T16:51:50Z

1 revision imported

← Older revision	Revision as of 16:51, 18 September 2015
(No difference)

Jmdonev at 18:21, 4 September 2015

2015-09-04T18:21:52Z

← Older revision		Revision as of 18:21, 4 September 2015
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	[[Category:Done 2015-07-24]]		[[Category:Done 2015-09-06]]
	[[File:radioact.gif\|400px\|framed\|right\|Figure 1. A diagram showing the repulsive Coulomb force within the nucleus along with the attractive strong force. Additionally, three forms of radioactive decay are shown.<ref name="RE1"/>]]		[[File:radioact.gif\|400px\|framed\|right\|Figure 1. A diagram showing the repulsive Coulomb force within the nucleus along with the attractive strong force. Additionally, three forms of radioactive decay are shown.<ref name="RE1"/>]]

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	The most common forms of radiation include [[alpha decay\|alpha]], [[beta decay\|beta]], and [[gamma decay\|gamma]] radiation, but other types of radioactive decay exist such as [[proton emission]] or [[neutron emission]], or [[spontaneous fission]] of large [[nuclei]].<ref name="RE2">US EPA, Berkeley Lab. (July 7, 2015). ''Radioactivity'' [Online]. Available: http://www2.lbl.gov/abc/wallchart/chapters/03/0.html</ref>		The most common forms of radiation include [[alpha decay\|alpha]], [[beta decay\|beta]], and [[gamma decay\|gamma]] radiation, but other types of radioactive decay exist such as [[proton emission]] or [[neutron emission]], or [[spontaneous fission]] of large [[nuclei]].<ref name="RE2">US EPA, Berkeley Lab. (July 7, 2015). ''Radioactivity'' [Online]. Available: http://www2.lbl.gov/abc/wallchart/chapters/03/0.html</ref>

	The radioactivity of elements can be used in a number of different applications, such as in [[medical isotope\|medicine]] and these elements act as the fuel in [[nuclear power plant]]s to [[electricity generation\|generate electricity]]. As well, the radiation from these elements can be used to [[irradiate food]]s and keep them from spoiling.		The radioactivity of elements can be used in a number of different applications, such as in [[medical isotope\|medicine]] and these elements act as the [[fuel]] in [[nuclear power plant]]s to [[electricity generation\|generate electricity]]. As well, the radiation from these elements can be used to [[irradiate food]]s and keep them from spoiling.

	==What Causes Radioactivity?==		==What Causes Radioactivity?==
	Whether or not a nuclide is radioactive has to do mainly with its nuclear stability. Nuclear [[isotope]]s that are unstable emit radiation as a result of the conflict in the strength of the repulsive [[Coulomb force]] between ~~protons~~ in the nucleus and the attractive [[strong nuclear force]] between nucleons.<ref name="RE1">HyperPhysics. (July 7, 2015). ''Radioactivity'' [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radact.html#c1</ref> If the Coulomb force and strong nuclear force do not balance, the nuclide in question lays outside the '''belt of stability''' and is radioactive. A number known as the '''neutron-to-proton ratio''' or '''N/Z ratio''' can be used to quickly see if the Coulomb force and strong nuclear force remain fairly balanced or out of balance.<ref name=book>Jeff C. Bryan. Introduction to Nuclear Science, 1st ed. Boca Raton, FL, U.S.A: CRC Press, 2009.</ref> For smaller elements near the top of the periodic table, the ratio for stability is nearly 1:1. As the nuclei get larger, the N/Z ratio increases slightly for stability.<ref name=book/> If a nucleus has too many protons or neutrons, it will likely undergo some sort of [[transmutation]] to reach a more stable state (where it changes to some new nuclide with a "better" N/Z ratio).<ref name=book/>		Whether or not a nuclide is radioactive has to do mainly with its nuclear stability. Nuclear [[isotope]]s that are unstable emit radiation as a result of the conflict in the strength of the repulsive [[Coulomb force]] between [[proton]]s in the nucleus and the attractive [[strong nuclear force]] between nucleons.<ref name="RE1">HyperPhysics. (July 7, 2015). ''Radioactivity'' [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radact.html#c1</ref> If the Coulomb [[force]] and strong nuclear force do not balance, the nuclide in question lays outside the '''belt of stability''' and is radioactive. A number known as the '''neutron-to-proton ratio''' or '''N/Z ratio''' can be used to quickly see if the [[Coulomb]] force and strong nuclear force remain fairly balanced or out of balance.<ref name=book>Jeff C. Bryan. Introduction to Nuclear Science, 1st ed. Boca Raton, FL, U.S.A: CRC Press, 2009.</ref> For smaller elements near the top of the periodic table, the ratio for stability is nearly 1:1. As the nuclei get larger, the N/Z ratio increases slightly for stability.<ref name=book/> If a nucleus has too many protons or neutrons, it will likely undergo some sort of [[transmutation]] to reach a more stable state (where it changes to some new nuclide with a "better" N/Z ratio).<ref name=book/>

	There are also more complex ways to decide whether or not a nucleus will exhibit radioactivity. For example, if a nucleus has either an odd number of protons or an odd number of neutrons, it tends to be radioactive regardless of whether or not the Coulomb and strong nuclear forces balance. The reason for a greater instability in nuclei with odd numbers of neutrons or protons is essentially because protons and neutrons like to "pair up" with particles of the same type, boosting stability.<ref name=book/> As well, there is something special about having certain numbers of protons or neutrons in a nucleus that promote stability. These numbers are known as [[magic number]]s.		There are also more complex ways to decide whether or not a nucleus will exhibit radioactivity. For example, if a nucleus has either an odd number of protons or an odd number of neutrons, it tends to be radioactive regardless of whether or not the Coulomb and strong nuclear forces balance. The reason for a greater instability in nuclei with odd numbers of neutrons or protons is essentially because protons and neutrons like to "pair up" with particles of the same type, boosting stability.<ref name=book/> As well, there is something special about having certain numbers of protons or neutrons in a nucleus that promote stability. These numbers are known as [[magic number]]s.
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	==Measuring Radioactivity==		==Measuring Radioactivity==
	Radioactivity can also be used to describe how much [[ionizing radiation]] is released by a radioactive material.<ref name=NRC>NRC. (July 8, 2015). ''Measuring Radiation'' [Online]. Available: http://www.nrc.gov/about-nrc/radiation/health-effects/measuring-radiation.html</ref> The SI unit of radioactivity is the [[becquerel]] (Bq), equal to one decay per second. The [[curie]] (Ci) was the original unit for radioactivity and is equal to 3.7×10<sup>10</sup> Bq.<ref name="RE3"/> [[Geiger counter]]s can be used to measure the radioactivity of a substance and these devices are widely known for the "clicking" noise they make when they detect a decay producing ionizing radiation.		Radioactivity can also be used to describe how much [[ionizing radiation]] is released by a radioactive material.<ref name=NRC>NRC. (July 8, 2015). ''Measuring Radiation'' [Online]. Available: http://www.nrc.gov/about-nrc/radiation/health-effects/measuring-radiation.html</ref> The SI [[units\|unit]] of radioactivity is the [[becquerel]] (Bq), equal to one decay per second. The [[curie]] (Ci) was the original unit for radioactivity and is equal to 3.7×10<sup>10</sup> Bq.<ref name="RE3"/> [[Geiger counter]]s can be used to measure the radioactivity of a substance and these devices are widely known for the "clicking" noise they make when they detect a decay producing ionizing radiation.

	Another way to measure how radioactive something is is to investigate its [[half-life]], since the half-life of an isotope is related to its radiation risk.		Another way to measure how radioactive something is is to investigate its [[half-life]], since the half-life of an isotope is related to its radiation risk.
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	However, in larger doses radiation does have negative effects on health. When radioactive materials decay, they produce '''[[ionizing radiation]]'''. Simply put, this type of radiation can strip [[electron]]s away from atoms or break [[chemical]] bonds (to make [[ion]]s). This causes damage to living tissues that cannot always be repaired.<ref name="RE2">US EPA. (July 8, 2015). ''Health Effects: Radiation'' [Online]. Available: http://www.epa.gov/radiation/understand/health_effects.html#q1</ref> Chronic exposure to radiation can lead to cancer (as a result of damage at the cellular or molecular level) or other mutations that can be harmful to fetuses. Effects from acute exposure to radiation appear quickly, and include burns and radiation poisoning. The symptoms of radiation poisoning include nausea, weakness, hair loss, and diminished organ function and this radiation sickness can result in death if the dose is high enough.<ref name="RE2"/>		However, in larger doses radiation does have negative effects on health. When radioactive materials decay, they produce '''[[ionizing radiation]]'''. Simply put, this type of radiation can strip [[electron]]s away from atoms or break [[chemical]] bonds (to make [[ion]]s). This causes damage to living tissues that cannot always be repaired.<ref name="RE2">US EPA. (July 8, 2015). ''Health Effects: Radiation'' [Online]. Available: http://www.epa.gov/radiation/understand/health_effects.html#q1</ref> Chronic exposure to radiation can lead to cancer (as a result of damage at the cellular or molecular level) or other mutations that can be harmful to fetuses. Effects from acute exposure to radiation appear quickly, and include burns and radiation poisoning. The symptoms of radiation poisoning include nausea, weakness, hair loss, and diminished organ function and this radiation sickness can result in death if the dose is high enough.<ref name="RE2"/>

	As well, some radiation is only harmful in certain circumstances. For example, smoke detectors generally contain a source of alpha particles known as americium (which is radioactive). The americium is used to detect the smoke. In the smoke detector itself, this source is radioactive but not harmful. However, because of the nature of alpha particles, the Americium is very dangerous if ingested. Smoke detectors save many lives every year, and changing the batteries once a year is a good idea. Dissecting smoke detectors however can be dangerous.		As well, some radiation is only harmful in certain circumstances. For example, smoke detectors generally contain a source of alpha particles known as americium (which is radioactive). The americium is used to detect the smoke. In the smoke detector itself, this source is radioactive but not harmful. However, because of the nature of alpha particles, the Americium is very dangerous if ingested. Smoke detectors save many lives every year, and changing the [[batteries]] once a year is a good idea. Dissecting smoke detectors however can be dangerous.

	==References==		==References==
	{{reflist}}		{{reflist}}
	[[Category:Uploaded]]		[[Category:Uploaded]]

J.williams: 1 revision imported

2015-08-26T21:31:34Z

1 revision imported

← Older revision	Revision as of 21:31, 26 August 2015
(No difference)

J.williams at 16:58, 12 August 2015

2015-08-12T16:58:48Z

New page

[[Category:Done 2015-07-24]]
[[File:radioact.gif|400px|framed|right|Figure 1. A diagram showing the repulsive Coulomb force within the nucleus along with the attractive strong force. Additionally, three forms of radioactive decay are shown.<ref name="RE1"/>]]

<onlyinclude>'''Radioactivity''' is a property of certain [[element]]s - such as [[uranium]] - of emitting [[energy]] in the form of [[radiation]] as a result of some sort of [[nuclear decay]] of an unstable [[atom]].<ref name="RE3">NRC Glossary. (July 8, 2015). ''Radioactivity'' [Online]. Available: http://www.nrc.gov/reading-rm/basic-ref/glossary/radioactivity.html</ref> Nuclei that exhibit radioactivity are known as '''radioactive nuclei'''. Additionally, radioactivity or simply activity can be used as a measurement to describe how many decays a [[radioactive]] atom goes through in a period of time.</onlyinclude><ref name=NRC/> These decays result in an ejection of [[particle]]s from the nucleus as it changes form and obtains a greater nuclear stability. Radioactivity can also be referred to as '''radioactive decay''' or '''nuclear decay'''.

The most common forms of radiation include [[alpha decay|alpha]], [[beta decay|beta]], and [[gamma decay|gamma]] radiation, but other types of radioactive decay exist such as [[proton emission]] or [[neutron emission]], or [[spontaneous fission]] of large [[nuclei]].<ref name="RE2">US EPA, Berkeley Lab. (July 7, 2015). ''Radioactivity'' [Online]. Available: http://www2.lbl.gov/abc/wallchart/chapters/03/0.html</ref>

The radioactivity of elements can be used in a number of different applications, such as in [[medical isotope|medicine]] and these elements act as the fuel in [[nuclear power plant]]s to [[electricity generation|generate electricity]]. As well, the radiation from these elements can be used to [[irradiate food]]s and keep them from spoiling.

==What Causes Radioactivity?==
Whether or not a nuclide is radioactive has to do mainly with its nuclear stability. Nuclear [[isotope]]s that are unstable emit radiation as a result of the conflict in the strength of the repulsive [[Coulomb force]] between protons in the nucleus and the attractive [[strong nuclear force]] between nucleons.<ref name="RE1">HyperPhysics. (July 7, 2015). ''Radioactivity'' [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radact.html#c1</ref> If the Coulomb force and strong nuclear force do not balance, the nuclide in question lays outside the '''belt of stability''' and is radioactive. A number known as the '''neutron-to-proton ratio''' or '''N/Z ratio''' can be used to quickly see if the Coulomb force and strong nuclear force remain fairly balanced or out of balance.<ref name=book>Jeff C. Bryan. Introduction to Nuclear Science, 1st ed. Boca Raton, FL, U.S.A: CRC Press, 2009.</ref> For smaller elements near the top of the periodic table, the ratio for stability is nearly 1:1. As the nuclei get larger, the N/Z ratio increases slightly for stability.<ref name=book/> If a nucleus has too many protons or neutrons, it will likely undergo some sort of [[transmutation]] to reach a more stable state (where it changes to some new nuclide with a "better" N/Z ratio).<ref name=book/>

There are also more complex ways to decide whether or not a nucleus will exhibit radioactivity. For example, if a nucleus has either an odd number of protons or an odd number of neutrons, it tends to be radioactive regardless of whether or not the Coulomb and strong nuclear forces balance. The reason for a greater instability in nuclei with odd numbers of neutrons or protons is essentially because protons and neutrons like to "pair up" with particles of the same type, boosting stability.<ref name=book/> As well, there is something special about having certain numbers of protons or neutrons in a nucleus that promote stability. These numbers are known as [[magic number]]s.

Most radioactive [[isotope]]s tend to be large, and the last completely stable nucleus is bismuth (which has 83 protons). These large radioactive elements tend to undergo alpha decay as it quickly lowers the number of protons and [[neutron]]s in the nucleus.<ref name=book/> Most nuclei that are found in nature are not radioactive, because all of the short-lived radioactive nuclei have already decayed, leaving a vast majority of stable nuclei. There are only 50 naturally occuring isotopes that exhibit radioactivity while there are around 270 stable isotopes.<ref name="RE2"/> Hundreds of short-lived isotopes have been created in laboratories and particle accelerators.

==Measuring Radioactivity==
Radioactivity can also be used to describe how much [[ionizing radiation]] is released by a radioactive material.<ref name=NRC>NRC. (July 8, 2015). ''Measuring Radiation'' [Online]. Available: http://www.nrc.gov/about-nrc/radiation/health-effects/measuring-radiation.html</ref> The SI unit of radioactivity is the [[becquerel]] (Bq), equal to one decay per second. The [[curie]] (Ci) was the original unit for radioactivity and is equal to 3.7×10<sup>10</sup> Bq.<ref name="RE3"/> [[Geiger counter]]s can be used to measure the radioactivity of a substance and these devices are widely known for the "clicking" noise they make when they detect a decay producing ionizing radiation.

Another way to measure how radioactive something is is to investigate its [[half-life]], since the half-life of an isotope is related to its radiation risk.

==Safety==
One common misconception about radioactivity is that ''any'' radioactive object is harmful to human health. This is not the case, however, as small doses radiation are not harmful to humans. In fact, there are many radioactive products that can be purchased and pose no health threats to humans. Bananas, smoke detectors, some ceramic dishware, cat litter, beer, and brazil nuts are all radioactive.<ref> Anne Marie Helmenstine. (July 7, 2015). ''10 Radioactive Everyday Objects'' [Online]. Available: http://chemistry.about.com/od/nucleardecay/ss/10-Radioactive-Products-Everyday-Items-That-Emit-Radiation.htm#showall</ref>

However, in larger doses radiation does have negative effects on health. When radioactive materials decay, they produce '''[[ionizing radiation]]'''. Simply put, this type of radiation can strip [[electron]]s away from atoms or break [[chemical]] bonds (to make [[ion]]s). This causes damage to living tissues that cannot always be repaired.<ref name="RE2">US EPA. (July 8, 2015). ''Health Effects: Radiation'' [Online]. Available: http://www.epa.gov/radiation/understand/health_effects.html#q1</ref> Chronic exposure to radiation can lead to cancer (as a result of damage at the cellular or molecular level) or other mutations that can be harmful to fetuses. Effects from acute exposure to radiation appear quickly, and include burns and radiation poisoning. The symptoms of radiation poisoning include nausea, weakness, hair loss, and diminished organ function and this radiation sickness can result in death if the dose is high enough.<ref name="RE2"/>

As well, some radiation is only harmful in certain circumstances. For example, smoke detectors generally contain a source of alpha particles known as americium (which is radioactive). The americium is used to detect the smoke. In the smoke detector itself, this source is radioactive but not harmful. However, because of the nature of alpha particles, the Americium is very dangerous if ingested. Smoke detectors save many lives every year, and changing the batteries once a year is a good idea. Dissecting smoke detectors however can be dangerous.

==References==
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