Curium information

Curium, ₉₆Cm
Curium
Pronunciation	/ˈkjʊəriəm/ (KURE-ee-əm)
Appearance	silvery metallic, glows purple in the dark
Mass number	[247]
Curium in the periodic table
	americium ← curium → berkelium
Atomic number (Z)	96
Group	f-block groups (no number)
Period	period 7
Block	f-block
Electron configuration	[Rn] 5f7 6d1 7s2
Electrons per shell	2, 8, 18, 32, 25, 9, 2
Physical properties
Phase at STP	solid
Melting point	1613 K (1340 °C, 2444 °F)
Boiling point	3383 K (3110 °C, 5630 °F)
Density (near r.t.)	13.51 g/cm3
Heat of fusion	13.85 kJ/mol
Atomic properties
Oxidation states	+3, +4, +5, +6 (an amphoteric oxide)
Electronegativity	Pauling scale: 1.3
Ionization energies	1st: 581 kJ/mol ; ;
Atomic radius	empirical: 174 pm
Covalent radius	169±3 pm
	Spectral lines of curium
Other properties
Natural occurrence	synthetic
Crystal structure	double hexagonal close-packed (dhcp)
Electrical resistivity	1.25 µΩ⋅m
Magnetic ordering	antiferromagnetic-paramagnetic transition at 52 K
CAS Number	7440-51-9
History
Naming	named after Marie Skłodowska-Curie and Pierre Curie
Discovery	Glenn T. Seaborg, Ralph A. James, Albert Ghiorso (1944)
Isotopes of curium v; e;
SF	–
CD	208Pb
ε	243Am
SF	–
SF	–
SF	–
SF	–
SF	–
α	246Pu
β−	250Bk
	Category: Curium; view; talk; edit; \| references

Curium is a synthetic chemical element; it has symbol Cm and atomic number 96. This transuranic actinide element was named after eminent scientists Marie and Pierre Curie, both known for their research on radioactivity. Curium was first intentionally made by the team of Glenn T. Seaborg, Ralph A. James, and Albert Ghiorso in 1944, using the cyclotron at Berkeley. They bombarded the newly discovered element plutonium (the isotope ²³⁹Pu) with alpha particles. This was then sent to the Metallurgical Laboratory at University of Chicago where a tiny sample of curium was eventually separated and identified. The discovery was kept secret until after the end of World War II. The news was released to the public in November 1947. Most curium is produced by bombarding uranium or plutonium with neutrons in nuclear reactors – one tonne of spent nuclear fuel contains ~20 grams of curium.

Curium is a hard, dense, silvery metal with a high melting and boiling point for an actinide. It is paramagnetic at ambient conditions, but becomes antiferromagnetic upon cooling, and other magnetic transitions are also seen in many curium compounds. In compounds, curium usually has valence +3 and sometimes +4; the +3 valence is predominant in solutions. Curium readily oxidizes, and its oxides are a dominant form of this element. It forms strongly fluorescent complexes with various organic compounds, but there is no evidence of its incorporation into bacteria and archaea. If it gets into the human body, curium accumulates in bones, lungs, and liver, where it promotes cancer.

All known isotopes of curium are radioactive and have small critical mass for a nuclear chain reaction. They mostly emit α-particles; radioisotope thermoelectric generators can use the heat from this process, but this is hindered by the rarity and high cost of curium. Curium is used in making heavier actinides and the ²³⁸Pu radionuclide for power sources in artificial cardiac pacemakers and RTGs for spacecraft. It served as the α-source in the alpha particle X-ray spectrometers of several space probes, including the Sojourner, Spirit, Opportunity, and Curiosity Mars rovers and the Philae lander on comet 67P/Churyumov–Gerasimenko, to analyze the composition and structure of the surface.

^ Kovács, Attila; Dau, Phuong D.; Marçalo, Joaquim; Gibson, John K. (2018). "Pentavalent Curium, Berkelium, and Californium in Nitrate Complexes: Extending Actinide Chemistry and Oxidation States". Inorg. Chem. 57 (15). American Chemical Society: 9453–9467. doi:10.1021/acs.inorgchem.8b01450. OSTI 1631597. PMID 30040397. S2CID 51717837.
^ Domanov, V. P.; Lobanov, Yu. V. (October 2011). "Formation of volatile curium(VI) trioxide CmO₃". Radiochemistry. 53 (5). SP MAIK Nauka/Interperiodica: 453–6. doi:10.1134/S1066362211050018. S2CID 98052484.
^ ^a ^b Schenkel, R. (1977). "The electrical resistivity of 244Cm metal". Solid State Communications. 23 (6): 389. Bibcode:1977SSCom..23..389S. doi:10.1016/0038-1098(77)90239-3.
^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.

[Kovács2018-1] Kovács, Attila; Dau, Phuong D.; Marçalo, Joaquim; Gibson, John K. (2018). "Pentavalent Curium, Berkelium, and Californium in Nitrate Complexes: Extending Actinide Chemistry and Oxidation States". Inorg. Chem. 57 (15). American Chemical Society: 9453–9467. doi:10.1021/acs.inorgchem.8b01450. OSTI 1631597. PMID 30040397. S2CID 51717837.

[CmO3-2] Domanov, V. P.; Lobanov, Yu. V. (October 2011). "Formation of volatile curium(VI) trioxide CmO₃". Radiochemistry. 53 (5). SP MAIK Nauka/Interperiodica: 453–6. doi:10.1134/S1066362211050018. S2CID 98052484.

[res-3] Schenkel, R. (1977). "The electrical resistivity of 244Cm metal". Solid State Communications. 23 (6): 389. Bibcode:1977SSCom..23..389S. doi:10.1016/0038-1098(77)90239-3.

[NUBASE2020-4] Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.

Curium information

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Curium

Isotopes of curium

Curium fluoride

Curium hexafluoride

Californium

Curium nitride

Americium

Per curiam decision

Berkelium

Actinide

MOX fuel

Kourion

96

Critical mass

Actinides in the environment

Curium Films

Synthetic element

Livermorium

Transuranium element

Metal

Aluminium

Oxygen

Gold

Cubic crystal system

Marie Curie