Difference between revisions of "Curium" - New World Encyclopedia

Vapor pressure
96	americium ← curium → berkelium
	periodic table
General
Name, Symbol, Number	curium, Cm, 96
Chemical series	actinides
Group, Period, Block	n/a, 7, f
Appearance	silvery
Atomic mass	(247) g/mol
Electron configuration	[Rn] 5f7 6d1 7s2
Electrons per shell	2, 8, 18, 32, 25, 9, 2
Physical properties
Phase	solid
Density (near r.t.)	13.51 g/cm³
Melting point	1613 K; (1340 °C, 2444 °F)
Boiling point	3383 K; (3110 °C, 5630 °F)
Heat of fusion	? 15 kJ/mol
Atomic properties
Crystal structure	hexagonal close-packed
Oxidation states	3; (amphoteric oxide)
Electronegativity	1.3 (Pauling scale)
Ionization energies	1st: 581 kJ/mol
Miscellaneous
Magnetic ordering	no data
CAS registry number	7440-51-9
Notable isotopes

Latest revision as of 06:46, 12 January 2024

Curium (chemical symbol Cm, atomic number 96) is a radioactive, metallic, transuranic element^[1] of the actinide series. It is produced synthetically by bombarding plutonium with alpha particles (helium ions). It was named after Marie Curie and her husband Pierre.

Two isotopes of curium (curium-242 and curium-244) can be produced in multigram amounts, making it feasible to study the element's chemical properties. The isotope curium-242 is the precursor to plutonium-238, the most common fuel for radioisotope thermoelectric generators (RTGs) that have been used to power certain space probes. Other curium isotopes (Cu-243, Cu-244) are also being investigated for their potential as fuels for RTGs.

History

Curium was first synthesized at the University of California, Berkeley by Glenn T. Seaborg, Ralph A. James, and Albert Ghiorso in 1944. The team named the new element after Marie Curie and her husband Pierre, who are famous for their work on radioactivity and the discovery of radium and polonium.

Curium was the third transuranic element to be discovered. The isotope curium-242 (half-life 163 days) was made by bombarding a plutonium-239 target with alpha particles in the 60-inch cyclotron at Berkeley. The element was chemically identified at the Metallurgical Laboratory (now Argonne National Laboratory) at the University of Chicago.

Louis Werner and Isadore Perlman created a visible sample of curium-242 hydroxide at the University of California in 1947 by bombarding americium-241 with neutrons. The elemental form of curium was prepared for the first time in 1951.

Notable characteristics

Curium is an inner transition metal of the actinide series, located in period seven of the periodic table, between americium and berkelium. It does not occur in nature.

The isotope curium-248 has been synthesized only in milligram quantities, but curium-242 and curium-244 are made in multigram amounts, which allows for the determination of some of the element's properties. Curium-244 can be made in quantity by subjecting plutonium to neutron bombardment.

A rare earth homolog, curium is somewhat chemically similar to gadolinium but with a more complex crystal structure. Chemically reactive, its metal is silvery-white in color and the element is more electropositive than aluminum (most trivalent curium compounds are slightly yellow).

Isotopes

Many radioisotopes of curium have been characterized, with the most stable being Cm-247, with a half-life of 1.56 × 10⁷ years; Cm-248, with a half-life of 3.40 × 10⁵ years; Cm-250, with a half-life of 9000 years; and Cm-245, with a half-life of 8500 years. All the remaining radioactive isotopes have half-lives of less than 30 years, and the majority of these have half-lives that are less than 33 days. This element also has four meta states, with the most stable being Cm-244m (t_½ 34 ms). The isotopes of curium range in atomic weight from 233.051 amu (Cm-233) to 252.085 amu (Cm-252).

Compounds

Known compounds of curium include the following:

Oxides:
- curium dioxide (CmO₂)
- curium trioxide (Cm₂O₃)
Halides:
- curium tetrafluoride (CmF₄)
- curium chloride (CmCl₃)
- curium bromide (CmBr₃)
- curium iodide (CmI₃)

Applications

Curium has been studied extensively as a potential fuel for Radioisotope thermoelectric generators that could be used to power space probes. Curium-242 can generate up to 120 watts of thermal energy per gram (W/g). Its very short half-life, however, makes it unsuitable as a power source for long-term use. Curium-242 is the precursor to plutonium-238, which is the most common fuel for RTGs. Curium-244 has also been studied as an energy source for RTGs having a maximum energy density about three W/g, but produces a large amount of neutron radiation from spontaneous fission. Curium-243, with a roughly 30-year half-life and good energy density (about 1.6 W/g), would seem to make an ideal fuel, but it produces significant amounts of gamma and beta radiation from radioactive decay products.

Nuclear fuel cycle

If MOX nuclear fuel^[2] is to be used in nuclear power reactors, it should contain little or no curium, because neutron activation of this element will create californium, a strong neutron emitter. The californium would pollute the back end of the fuel cycle and increase the dose to workers.

Biological effects

Curium bio-accumulates in bone tissue where its radiation destroys bone marrow and thus stops the production of red blood cells.

Notes

↑ "Transuranic elements" are the chemical elements with atomic numbers greater than that of uranium (atomic number 92).
↑ "MOX" (mixed oxide) nuclear fuel is a blend of plutonium with natural uranium, reprocessed uranium, or depleted uranium. Its behavior is similar to that of low enriched uranium (LEU) fuel, and it is an alternative to the LEU used in the light water reactors that predominate nuclear power generation.

References
ISBN links support NWE through referral fees

Emsley, John. Nature's Building Blocks: An A–Z Guide to the Elements. Oxford: Oxford Univ. Press, 2001. ISBN 0198503407
Greenwood, N.N., and A. Earnshaw. Chemistry of the Elements 2nd ed. Oxford, UK; Burlington, MA: Butterworth-Heinemann, 1998. ISBN 0750633654
Hampel, Clifford A. The Encyclopedia of the Chemical Elements. New York: Reinhold Book Corp, 1968. ISBN 0442155980
Morss, Lester R., Norman M. Edelstein, and Jean Fuger, eds. The Chemistry of the Actinide and Transactinide Elements. 3rd ed. 5 vols. Joseph J. Katz, adapter. Dordrecht: Springer, 2006. ISBN 1402035551
Stwertka, Albert. Guide to the Elements. Rev. ed. Oxford: Oxford University Press, 1998. ISBN 0195080831

External links

All links retrieved January 12, 2024.

It's Elemental: Curium Jefferson Lab.
Curium. The University of Sheffield and WebElements Ltd.

Credits

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Curium ^history

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[1] "Transuranic elements" are the chemical elements with atomic numbers greater than that of uranium (atomic number 92).

[2] "MOX" (mixed oxide) nuclear fuel is a blend of plutonium with natural uranium, reprocessed uranium, or depleted uranium. Its behavior is similar to that of low enriched uranium (LEU) fuel, and it is an alternative to the LEU used in the light water reactors that predominate nuclear power generation.

[1]

[2]

@@ Line 1: / Line 1: @@
-{{Claimed}}{{Images OK}}
+{{Copyedited}}{{Images OK}}{{Submitted}}{{Approved}}{{Paid}}
 {{Elementbox_header | number=96 | symbol=Cm | name=curium | left=[[americium]] | right=[[berkelium]] | above=[[gadolinium|Gd]] | below=(Uqh) | color1=#ff99cc | color2=black }}
 {{Elementbox_series | [[actinide]]s }}
@@ Line 22: / Line 22: @@
 {{Elementbox_magnetic | no data }}
 {{Elementbox_cas_number | 7440-51-9 }}
-{{Elementbox_isotopes_begin | color1=#ff99cc | color2=black }}
+{{Elementbox_isotopes_begin | isotopesof=curium | color1=#ff99cc | color2=black }}
 {{Elementbox_isotopes_decay2 | mn=242 | sym=Cm
   | na=[[synthetic radioisotope|syn]] | hl=160 days
@@ Line 59: / Line 59: @@
 {{Elementbox_footer | color1=#ff99cc | color2=black }}
-'''Curium''' (chemical symbol '''Cm''', [[atomic number]] 96) is a synthetic [[chemical element]]. A [[Radioactive decay|radioactive]] [[metal]]lic [[transuranic element]] of the [[actinide]] series, curium is produced by bombarding [[plutonium]] with [[alpha particle]]s ([[helium]] [[ion]]s) and was named for [[Maria Sklodowska-Curie|Marie Curie]] and her husband [[Pierre Curie|Pierre]].
+'''Curium''' (chemical symbol '''Cm''', [[atomic number]] 96) is a [[Radioactive decay|radioactive]], [[metal]]lic, [[transuranic element]]<ref>"Transuranic elements" are the [[chemical element]]s with [[atomic number]]s greater than that of [[uranium]] (atomic number 92).</ref> of the [[actinide]] series. It is produced synthetically by bombarding [[plutonium]] with [[alpha particle]]s ([[helium]] [[ion]]s). It was named after [[Marie Curie]] and her husband [[Pierre Curie|Pierre]].
+{{toc}}
+Two [[isotope]]s of curium (curium-242 and curium-244) can be produced in multigram amounts, making it feasible to study the element's chemical properties. The isotope curium-242 is the precursor to [[plutonium]]-238, the most common fuel for [[radioisotope thermoelectric generator]]s (RTGs) that have been used to power certain space probes. Other curium isotopes (Cu-243, Cu-244) are also being investigated for their potential as fuels for RTGs.
 == History ==
-Curium was [[discoveries of the chemical elements|first synthesized]] at the [[University of California, Berkeley]] by [[Glenn T. Seaborg]], Ralph A. James, and [[Albert Ghiorso]] in [[1944]]. The team named the new element after [[Marie Curie]] and her husband [[Pierre Curie|Pierre]] who are famous for discovering [[radium]] and for their work in [[radioactivity]]. It was chemically identified at the Metallurgical Laboratory (now [[Argonne National Laboratory]]) at the [[University of Chicago]]. It was actually the third transuranium element to be discovered even though it is the second in the series. Curium-242 ([[half-life]] 163 days) and one [[free neutron]] were made by bombarding [[alpha particle]]s onto a [[plutonium]]-239 target in the 60-inch [[cyclotron]] at Berkeley.  Louis Werner and  Isadore Perlman created a visible sample of curium-242 [[hydroxide]] at the [[University of California]] in [[1947]] by bombarding [[americium]]-241 with neutrons. Curium was made in its elemental form in [[1951]] for the first time.
+Curium was [[discoveries of the chemical elements|first synthesized]] at the [[University of California, Berkeley]] by [[Glenn T. Seaborg]], Ralph A. James, and [[Albert Ghiorso]] in 1944. The team named the new element after [[Marie Curie]] and her husband [[Pierre Curie|Pierre]], who are famous for their work on [[radioactivity]] and the discovery of [[radium]] and [[polonium]].
+Curium was the third transuranic element to be discovered. The isotope curium-242 ([[half-life]] 163 days) was made by bombarding a [[plutonium]]-239 target with [[alpha particle]]s in the 60-inch [[cyclotron]] at Berkeley. The element was chemically identified at the Metallurgical Laboratory (now [[Argonne National Laboratory]]) at the [[University of Chicago]].
+Louis Werner and Isadore Perlman created a visible sample of curium-242 [[hydroxide]] at the [[University of California]] in 1947 by bombarding [[americium]]-241 with neutrons. The elemental form of curium was prepared for the first time in 1951.
 == Notable characteristics ==
-Curium is an [[inner transition metal]] (or actinide) that lies in period 7 of the [[periodic table]], between [[americium]] and [[berkelium]].
+Curium is an [[inner transition metal]] of the actinide series, located in period seven of the [[periodic table]], between [[americium]] and [[berkelium]]. It does not occur in nature.
+The [[isotope]] curium-248 has been synthesized only in milligram quantities, but curium-242 and curium-244 are made in multigram amounts, which allows for the determination of some of the element's properties. Curium-244 can be made in quantity by subjecting [[plutonium]] to [[neutron]] bombardment.
+A [[rare earth]] homolog, curium is somewhat chemically similar to [[gadolinium]] but with a more complex [[crystal structure]]. Chemically reactive, its [[metal]] is silvery-white in color and the element is more [[electropositive]] than [[aluminum]] (most trivalent curium [[compound (chemistry)|compound]]s are slightly yellow).
-The [[isotope]] curium-248 has been synthesized only in milligram quantities, but curium-242 and curium-244 are made in multigram amounts, which allows for the determination of some of the element's properties. Curium-244 can be made in quantity by subjecting [[plutonium]] to [[neutron]] bombardment. Curium does not occur in nature. There are few commercial applications, for curium but it may one day be useful in radioisotope thermoelectric generators. Curium [[bio-accumulate]]s in [[bone]] tissue where its radiation destroys  [[bone marrow]] and thus stops [[red blood cell]] creation.
+=== Isotopes ===
-A [[rare earth]] homolog, curium is somewhat chemically similar to [[gadolinium]] but with a more complex [[crystal structure]]. Chemically reactive, its [[metal]] is silvery-white in color and the element is more [[electropositive]] than [[aluminium]] (most trivalent curium [[compound (chemistry)|compound]]s  are slightly yellow).
+Many [[radioisotope]]s of curium have been characterized, with the most stable being Cm-247, with a [[half-life]] of 1.56 &times; 10<sup>7</sup> [[year]]s; Cm-248, with a half-life of 3.40 &times; 10<sup>5</sup> years; Cm-250, with a half-life of 9000 years; and Cm-245, with a half-life of 8500 years. All the remaining [[radioactive]] isotopes have half-lives of less than 30 years, and the majority of these have half-lives that are less than 33 days. This element also has four [[meta state]]s, with the most stable being Cm-244m (t<sub>½</sub> 34 ms). The isotopes of curium range in [[atomic weight]] from 233.051 [[atomic mass unit|amu]] (Cm-233) to 252.085 amu (Cm-252).
-Curium has been studied greatly as a potential fuel for [[RTG|Radioisotope thermoelectric generators]]. Curium-242 can generate up to 120 [[watt]]s of thermal [[energy]] per gram (W/g); its very short half-life though makes it undesirable as a power source for long-term use. Curium-242 is the precursor to [[plutonium]]-238 which is the most common fuel for RTGs. Curium-244 has also been studied as an energy source for RTGs having a maximum energy density ~3 W/g, but produces a large amount of neutron radiation from [[Spontaneous_fission|spontaneous fission]]. Curium-243 with a ~30 year half-life and good energy density of ~1.6 W/g would seem to make an ideal fuel, but it produces significant amounts of [[Gamma_ray|gamma]] and [[Beta_ray|beta]] radiation from radioactive decay products.
+== Compounds ==
-Compounds include:
+Known compounds of curium include the following:
-*curium dioxide (Cm[[oxygen|O]]<sub>2</sub>)
+* Oxides:
-*curium trioxide (Cm<sub>2</sub>O<sub>3</sub>)
+**curium dioxide (Cm[[oxygen|O]]<sub>2</sub>)
-*curium bromide (Cm[[bromine|Br]]<sub>3</sub>)
+**curium trioxide (Cm<sub>2</sub>O<sub>3</sub>)
-*curium chloride (Cm[[chlorine|Cl]]<sub>3</sub>)
+* Halides:
-*curium tetrafluoride (Cm[[Fluorine|F]]<sub>4</sub>)
+**curium tetrafluoride (Cm[[Fluorine|F]]<sub>4</sub>)
-*curium iodide (Cm[[iodine|I]]<sub>3</sub>)
+**curium chloride (Cm[[chlorine|Cl]]<sub>3</sub>)
+**curium bromide (Cm[[bromine|Br]]<sub>3</sub>)
+**curium iodide (Cm[[iodine|I]]<sub>3</sub>)
-=== Isotopes ===
+== Applications ==
-Many [[radioisotope]]s of curium have been characterized, with the most stable being Cm-247 with a [[half-life]] of 1.56 &times; 10<sup>7</sup> [[year]]s, Cm-248 with a half-life of 3.40 &times; 10<sup>5</sup> years, Cm-250 with a half-life of 9000 years, and Cm-245 with a half-life of 8500 years.  All of the remaining [[radioactive]] isotopes have half-lifes that are less than 30 years, and the majority of these have half lifes that are less than 33 days. This element also has 4 [[meta state]]s, with the most stable being Cm-244m (t<sub>½</sub> 34 ms). The isotopes of curium range in [[atomic weight]] from 233.051  [[atomic mass unit|u]] (Cm-233) to 252.085 u (Cm-252).
+Curium has been studied extensively as a potential fuel for [[RTG|Radioisotope thermoelectric generators]] that could be used to power space probes. Curium-242 can generate up to 120 [[watt]]s of thermal [[energy]] per gram (W/g). Its very short half-life, however, makes it unsuitable as a power source for long-term use. Curium-242 is the precursor to [[plutonium]]-238, which is the most common fuel for RTGs. Curium-244 has also been studied as an energy source for RTGs having a maximum energy density about three W/g, but produces a large amount of neutron radiation from [[Spontaneous_fission|spontaneous fission]]. Curium-243, with a roughly 30-year half-life and good energy density (about 1.6 W/g), would seem to make an ideal fuel, but it produces significant amounts of [[Gamma_ray|gamma]] and [[Beta_ray|beta]] radiation from radioactive decay products.
 == Nuclear fuel cycle ==
-The [[MOX]] which is to be used in power reactors should contain little or no curium as the neutron activation of this element will create [[californium]] which is a strong [[neutron]] emitter. The californium would [[pollute]] the back end of the fuel cycle and increase the dose to workers. Hence if the [[Minor actinides]] are to be used as fuel in a thermal neutron reactor the curium should be excluded from the fuel or placed in special fuel rods where it is the only actinide present.
+If [[MOX]] [[nuclear fuel]]<ref>"MOX" (mixed oxide) [[nuclear fuel]] is a blend of [[plutonium]] with [[natural uranium]], [[reprocessed uranium]], or [[depleted uranium]]. Its behavior is similar to that of low [[enriched uranium]] (LEU) fuel, and it is an alternative to the LEU used in the [[light water reactor]]s that predominate [[nuclear power]] generation.</ref> is to be used in nuclear power reactors, it should contain little or no curium, because neutron activation of this element will create [[californium]], a strong [[neutron]] emitter. The californium would [[pollute]] the back end of the fuel cycle and increase the dose to workers.
+== Biological effects ==
+Curium [[bio-accumulate]]s in [[bone]] tissue where its radiation destroys [[bone marrow]] and thus stops the production of [[red blood cell]]s.
 == See also ==
@@ Line 98: / Line 114: @@
 * [[Periodic table]]
 * [[Radioactive decay]]
+== Notes ==
+<references/>
 ==References==
-* Emsley, John. 2001. ''Nature's Building Blocks: An A&ndash;Z Guide to the Elements''. Oxford: Oxford Univ. Press. ISBN 0198503407 and ISBN 978-0198503408.
+* Emsley, John. ''Nature's Building Blocks: An A&ndash;Z Guide to the Elements''. Oxford: Oxford Univ. Press, 2001. ISBN 0198503407
+* Greenwood, N.N., and A. Earnshaw. ''Chemistry of the Elements'' 2nd ed. Oxford, UK; Burlington, MA: Butterworth-Heinemann, 1998. ISBN 0750633654
+* Hampel, Clifford A. ''The Encyclopedia of the Chemical Elements''. New York: Reinhold Book Corp, 1968. ISBN 0442155980
+* Morss, Lester R., Norman M. Edelstein, and Jean Fuger, eds. ''The Chemistry of the Actinide and Transactinide Elements''. 3rd ed. 5 vols. Joseph J. Katz, adapter. Dordrecht: Springer, 2006. ISBN 1402035551
+* Stwertka, Albert. ''Guide to the Elements''. Rev. ed. Oxford: Oxford University Press, 1998. ISBN 0195080831
-* Greenwood, N.N., and A. Earnshaw. 1998. ''Chemistry of the Elements'' 2nd ed. Oxford, UK; Burlington, MA: Butterworth-Heinemann. ISBN 0750633654. [http://www.knovel.com/knovel2/Toc.jsp?BookID=402&VerticalID=0 Online version].
+== External links ==
+All links retrieved January 12, 2024.
-* Hampel, Clifford A. 1968. ''The Encyclopedia of the Chemical Elements''. New York: Reinhold Book Corp. ISBN 0442155980 and ISBN 978-0442155988.
-* Morss, Lester R., Norman M. Edelstein, and Jean Fuger, eds. 2006. ''The Chemistry of the Actinide and Transactinide Elements''. 3rd ed. 5 vols. Joseph J. Katz, adapter. Dordrecht: Springer. ISBN 1402035551 and ISBN 978-1402035555.
+* [http://education.jlab.org/itselemental/ele096.html It's Elemental: Curium] ''Jefferson Lab''.
+* [http://www.webelements.com/webelements/elements/text/Cm/index.html Curium.] ''The University of Sheffield and WebElements Ltd.''
-* Stwertka, Albert. 1998. ''Guide to the Elements''. Rev. ed. Oxford: Oxford University Press. ISBN 0-19-508083-1.
-* Chemistry Operations. 2003. [http://periodic.lanl.gov/elements/96.html "Curium"] ''Los Alamos National Laboratory, Chemistry Division''. Retrieved March 14, 2007.
-== External links ==
-* [http://education.jlab.org/itselemental/ele096.html It's Elemental - Curium]
-* [http://www.ead.anl.gov/pub/doc/curium.pdf Human Health Fact Sheet on Curium]
-*[http://www.webelements.com/webelements/elements/text/Cm/index.html WebElements.com - Curium]
-*[http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@na+@rel+curium,+radioactive NLM Hazardous Substances Databank &ndash; Curium, Radioactive]
 [[Category:Physical sciences]]