Curium (Cm)

Radioactive metallic transuranic element. Belongs to actinoid series. Nine known isotopes, Cm-247 has a half-life of 1.64*10^7 years. First identified by Glenn T. Seaborg and associates in 1944, first produced by L.B. Werner and I. Perlman in 1947 by bombarding americium-241 with Neutrons. Named for Marie Curie.

Atomic Number	96
Atomic Weight	247
Mass Number	231

Group
Period	7
Block	f

Protons	96 p⁺
Neutrons	135 n⁰
Electrons	96 e^-

Properties

Energy
Atomic Radius	276 pm
Molar Volume	18.28 cm³/mol
Covalent Radius	166 pm 136 pm 169 pm
Metallic Radius
Ionic Radius	97 pm 85 pm 95 pm 114.7 pm
Crystal Radius	111 pm 99 pm 109 pm 128.7 pm
Van der Waals Radius	245 pm 332.6 pm
Density	13.51 g/cm³
Proton Affinity
Electron Affinity
Ionization Energy	5.9914 eV/particle 10 eV/particle 20.1 eV/particle 37.7 eV/particle 51 eV/particle 69.1 eV/particle 97 eV/particle 112 eV/particle 128 eV/particle 144 eV/particle 167 eV/particle 190 eV/particle 212 eV/particle 235 eV/particle 253 eV/particle 272 eV/particle 311 eV/particle 332 eV/particle 460 eV/particle 489 eV/particle 518 eV/particle 550 eV/particle 580 eV/particle 611 eV/particle 657 eV/particle 689 eV/particle 723 eV/particle 755 eV/particle 910 eV/particle 950 eV/particle 990 eV/particle 1,030 eV/particle 1,140 eV/particle 1,180 eV/particle 1,300 eV/particle 1,340 eV/particle 1,480 eV/particle 1,560 eV/particle 1,640 eV/particle 1,730 eV/particle 1,810 eV/particle 1,890 eV/particle 1,980 eV/particle 2,060 eV/particle 2,160 eV/particle 2,240 eV/particle 2,320 eV/particle 2,410 eV/particle 2,490 eV/particle 2,580 eV/particle 2,976 eV/particle 3,050 eV/particle 3,125 eV/particle 3,207 eV/particle 3,284 eV/particle 3,360 eV/particle 3,515 eV/particle 3,593 eV/particle 3,679 eV/particle 3,758 eV/particle 4,078 eV/particle 4,156 eV/particle 4,239 eV/particle 4,317 eV/particle 4,791 eV/particle 4,880 eV/particle 5,110 eV/particle 5,200 eV/particle 8,270 eV/particle 8,440 eV/particle 8,620 eV/particle 8,820 eV/particle 9,000 eV/particle 9,180 eV/particle 9,630 eV/particle 9,820 eV/particle 10,020 eV/particle 10,220 eV/particle 10,760 eV/particle 10,920 eV/particle 11,100 eV/particle 11,270 eV/particle 12,740 eV/particle 12,950 eV/particle 13,360 eV/particle 13,550 eV/particle 27,740 eV/particle 28,180 eV/particle 28,700 eV/particle 29,100 eV/particle 34,600 eV/particle 35,200 eV/particle 36,000 eV/particle 36,493 eV/particle 143,299.6 eV/particle 145,743 eV/particle

Heat of Vaporization
Heat of Fusion
Heat of Formation	386 kJ/mol
Electrons
Electron Shells	2, 8, 18, 32, 25, 9, 2

Valence Electrons	2

Electron Configuration	[Rn] 5f⁷ 6d¹ 7s²

Oxidation States	3, 4, 5, 6
Electronegativity	0.17439
Electrophilicity
Phases
Phase	Solid
Gas Phase
Boiling Point
Melting Point	1,618.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual
Color	Silver #ffffff #785ce3 #785ce3
Appearance	silvery metallic, glows purple in the dark
Refractive Index
Thermodynamic Properties
Thermal Conductivity
Thermal Expansion
Molar Heat Capacity
Specific Heat Capacity
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
Type
Electrical Conductivity
Electrical Resistivity
Superconducting Point
Magnetism
Type
Magnetic Susceptibility (Mass)
Magnetic Susceptibility (Molar)
Magnetic Susceptibility (Volume)
Magnetic Ordering
Curie Point
Neel Point
Structure
Crystal Structure	Simple Hexagonal ()
Lattice Constant
Lattice Angles	π/2, π/2, 2 π/3
Mechanical Properties
Hardness
Bulk Modulus
Shear Modulus
Young Modulus
Poisson Ratio
Speed of Sound
Classification
Category	Actinides, Actinides
CAS Group
IUPAC Group
Glawe Number	40
Mendeleev Number	28
Pettifor Number	41
Geochemical Class
Goldschmidt Class	synthetic
Other
Gas Basicity
Dipole Polarizability	144 ± 25 a₀
C6 Dispersion Coefficient
Allotropes
Neutron Cross Section	60
Neutron Mass Absorption
Quantum Numbers	9D2
Space Group	194 (P63/mmc)

Isotopes of Curium

Stable Isotopes	0
Unstable Isotopes	22
Radioactive Isotopes	22

²³¹Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	231.050746 ± 0.000322 Da
Mass Number	231
G-Factor
Half Life
Spin	3/2
Quadrupole Moment
Discovery Year
Parity	+

²³¹Cm Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%
α (α emission)	%

²³²Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	232.04974 ± 0.000216 Da
Mass Number	232
G-Factor	0
Half Life
Spin	0
Quadrupole Moment	0
Discovery Year
Parity	+

²³²Cm Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%
α (α emission)	%

²³³Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	233.050771485 ± 0.000087059 Da
Mass Number	233
G-Factor
Half Life	27 ± 10 s
Spin	3/2
Quadrupole Moment
Discovery Year	2001
Parity	+

²³³Cm Decay Modes

Decay Mode	Intensity
α (α emission)	20%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	80%

²³⁴Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	234.050158568 ± 0.000018333 Da
Mass Number	234
G-Factor	0
Half Life	52 ± 9 s
Spin	0
Quadrupole Moment	0
Discovery Year	2001
Parity	+

²³⁴Cm Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	71%
α (α emission)	27%
SF (spontaneous fission)	2%

²³⁵Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	235.051545 ± 0.00011 Da
Mass Number	235
G-Factor
Half Life	7 ± 3 m
Spin	5/2
Quadrupole Moment
Discovery Year	1981
Parity	+

²³⁵Cm Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%
α (α emission)	4%

²³⁶Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	236.051372112 ± 0.000018931 Da
Mass Number	236
G-Factor	0
Half Life	6.8 ± 0.8 m
Spin	0
Quadrupole Moment	0
Discovery Year	2010
Parity	+

²³⁶Cm Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	82%
α (α emission)	18%
SF (spontaneous fission)	%

²³⁷Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	237.052868988 ± 0.00007987 Da
Mass Number	237
G-Factor
Half Life
Spin	5/2
Quadrupole Moment
Discovery Year	2002
Parity	+

²³⁷Cm Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%
α (α emission)	%

²³⁸Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	238.053081606 ± 0.000013133 Da
Mass Number	238
G-Factor	0
Half Life	2.2 ± 0.4 h
Spin	0
Quadrupole Moment	0
Discovery Year	1994
Parity	+

²³⁸Cm Decay Modes

Decay Mode	Intensity
ϵ (electron capture)	%
α (α emission)	3.84%
SF (spontaneous fission)	0.048%

²³⁹Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	239.054908519 ± 0.000161107 Da
Mass Number	239
G-Factor
Half Life	2.5 ± 0.4 h
Spin	7/2
Quadrupole Moment
Discovery Year	1952
Parity	-

²³⁹Cm Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
α (α emission)	6.2%

²⁴⁰Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	240.055528233 ± 0.000002045 Da
Mass Number	240
G-Factor	0
Half Life	30.4 ± 3.7 d
Spin	0
Quadrupole Moment	0
Discovery Year	1949
Parity	+

²⁴⁰Cm Decay Modes

Decay Mode	Intensity
α (α emission)	100%
ϵ (electron capture)	%
SF (spontaneous fission)	3.9%

²⁴¹Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	241.057651218 ± 0.000001725 Da
Mass Number	241
G-Factor
Half Life	32.8 ± 0.2 d
Spin	1/2
Quadrupole Moment	0
Discovery Year	1952
Parity	+

²⁴¹Cm Decay Modes

Decay Mode	Intensity
ϵ (electron capture)	99%
α (α emission)	1%

²⁴²Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	242.058834187 ± 0.000001224 Da
Mass Number	242
G-Factor	0
Half Life	162.8 ± 0.2 d
Spin	0
Quadrupole Moment	0
Discovery Year	1949
Parity	+

²⁴²Cm Decay Modes

Decay Mode	Intensity
α (α emission)	100%
SF (spontaneous fission)	6.2%
34Si	1.1%
2β⁺ (double β⁺ decay)	%

²⁴³Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	243.061387329 ± 0.000001605 Da
Mass Number	243
G-Factor	0.16 ± 0.032
Half Life	29.1 ± 0.1 y
Spin	5/2
Quadrupole Moment
Discovery Year	1950
Parity	+

²⁴³Cm Decay Modes

Decay Mode	Intensity
α (α emission)	100%
ϵ (electron capture)	0.29%
SF (spontaneous fission)	5.3%

²⁴⁴Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	244.062750622 ± 0.000001187 Da
Mass Number	244
G-Factor	0
Half Life	18.11 ± 0.03 y
Spin	0
Quadrupole Moment	0
Discovery Year	1950
Parity	+

²⁴⁴Cm Decay Modes

Decay Mode	Intensity
α (α emission)	100%
SF (spontaneous fission)	1.37%

²⁴⁵Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	245.065491047 ± 0.000001233 Da
Mass Number	245
G-Factor	0.14285714285714 ± 0.028571428571429
Half Life	8.25 ± 0.07 ky
Spin	7/2
Quadrupole Moment
Discovery Year	1954
Parity	+

²⁴⁵Cm Decay Modes

Decay Mode	Intensity
α (α emission)	100%
SF (spontaneous fission)	6.1%

²⁴⁶Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	246.067222016 ± 0.000001637 Da
Mass Number	246
G-Factor	0
Half Life	4.706 ± 0.04 ky
Spin	0
Quadrupole Moment	0
Discovery Year	1954
Parity	+

²⁴⁶Cm Decay Modes

Decay Mode	Intensity
α (α emission)	99.97385%
SF (spontaneous fission)	0.02615%

²⁴⁷Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	247.070352678 ± 0.000004076 Da
Mass Number	247
G-Factor	0.08 ± 0.015555555555556
Half Life	15.6 ± 0.5 My
Spin	9/2
Quadrupole Moment
Discovery Year	1954
Parity	-

²⁴⁷Cm Decay Modes

Decay Mode	Intensity
α (α emission)	100%

²⁴⁸Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	248.072349086 ± 0.000002531 Da
Mass Number	248
G-Factor	0
Half Life	348 ± 6 ky
Spin	0
Quadrupole Moment	0
Discovery Year	1956
Parity	+

²⁴⁸Cm Decay Modes

Decay Mode	Intensity
α (α emission)	91.61%
SF (spontaneous fission)	8.39%
2β⁻ (double β⁻ decay)	%

²⁴⁹Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	249.075953992 ± 0.000002545 Da
Mass Number	249
G-Factor
Half Life	64.15 ± 0.03 m
Spin	1/2
Quadrupole Moment	0
Discovery Year	1956
Parity	+

²⁴⁹Cm Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

²⁵⁰Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	250.078357541 ± 0.000011029 Da
Mass Number	250
G-Factor	0
Half Life
Spin	0
Quadrupole Moment	0
Discovery Year	1966
Parity	+

²⁵⁰Cm Decay Modes

Decay Mode	Intensity
SF (spontaneous fission)	74%
α (α emission)	%
β⁻ (β⁻ decay)	%

²⁵¹Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	251.082284988 ± 0.000024367 Da
Mass Number	251
G-Factor
Half Life	16.8 ± 0.2 m
Spin	3/2
Quadrupole Moment
Discovery Year	1978
Parity	+

²⁵¹Cm Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

²⁵²Cm

Abundance	Radioactive ☢️
Relative Atomic Mass	252.08487 ± 0.00032 Da
Mass Number	252
G-Factor	0
Half Life
Spin	0
Quadrupole Moment	0
Discovery Year
Parity	+

²⁵²Cm Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%
α (α emission)	%

History

Curium was discovered by Glenn T. Seaborg, Ralph A. James and Albert Ghiorso in 1944 at the University of California, Berkeley. It was produced by bombarding plutonium with alpha particles during the Manhattan Project. Curium metal was produced only in 1951 by reduction of curium fluoride with barium. Curium is named after Madame Curie and her husband Pierre Curie

Discoverers	G.T.Seaborg, R.A.James, A.Ghiorso
Discovery Location	United States
Discovery Year	1944
Etymology (Name Origin)	Named in honor of Pierre and Marie Curie.
Pronunciation	KYOOR-i-em (English)

Curium is harmful due to its radioactivity

Curium accumulates in the bones, lungs and liver, where it promotes cancer

Uses

Curium is mainly used for scientific research purposes. Curium is a common starting material for the production of higher transuranic elements and transactinides. The most practical application of ²⁴⁴Cm is as α-particle source in the alpha particle X-ray spectrometers (APXS). It has no significant commercial applications.

Sources

Made by bombarding plutonium with helium ions. So radioactive it glows in the dark.

Abundance
Abundance in Earth's crust
Abundance in Oceans
Abundance in Human Body	0 %
Abundance in Meteor	0 %
Abundance in Sun	0 %
Abundance in Universe	0 %

Nuclear Screening Constants

Curium on ChemicalAid

Australian Educational Vocabulary ID	scot/3513
CAB ID	7536
CAS Registry Number	7440-51-9
Catholic Encyclopedia ID	04572c
ChEBI ID	33390
ChemSpider ID	22415
DSSTOX compound identifier	DTXCID80147881
DSSTox substance ID	DTXSID80225390
Den Store Danske ID	curium
Encyclopædia Britannica Online ID	science/curium-chemical-element
Encyclopædia Universalis ID	curium
Freebase ID	/m/025tkv0
French Vikidia ID	Curium
GND ID	4148404-6
Great Russian Encyclopedia Online ID	2127358
InChI	InChI=1S/Cm
InChIKey	NIWWFAAXEMMFMS-UHFFFAOYSA-N
KBpedia ID	Curium
Library of Congress authority ID	sh85034863
MeSH descriptor ID	D003476
NALT ID	3199
National Diet Library ID	00575294
National Library of Israel J9U ID	987007538486405171
OmegaWiki Defined Meaning	157032
OpenAlex ID	C555352317
PDB ligand ID	ZCM
PDB structure ID	4ZHF
PubChem CID	23979
Quora topic ID	Curium
Römpp online ID	RD-03-02962
Store norske leksikon ID	curium
Treccani ID	curio
UNII	M5LL84MZ2W
WordNet 3.1 Synset ID	14660398-n

Curium (Cm)

Properties

Isotopes of Curium

231Cm

231Cm Decay Modes

232Cm

232Cm Decay Modes

233Cm

233Cm Decay Modes

234Cm

234Cm Decay Modes

235Cm

235Cm Decay Modes

236Cm

236Cm Decay Modes

237Cm

237Cm Decay Modes

238Cm

238Cm Decay Modes

239Cm

239Cm Decay Modes

240Cm

240Cm Decay Modes

241Cm

241Cm Decay Modes

242Cm

242Cm Decay Modes

243Cm

243Cm Decay Modes

244Cm

244Cm Decay Modes

245Cm

245Cm Decay Modes

246Cm

246Cm Decay Modes

247Cm

247Cm Decay Modes

248Cm

248Cm Decay Modes

249Cm

249Cm Decay Modes

250Cm

250Cm Decay Modes

251Cm

251Cm Decay Modes

252Cm

252Cm Decay Modes