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About Californium

Californium Bohr

Californium is a radioactive element first synthesized by Stanley G. Thompson, Kenneth Street Jr., Albert Ghioirso, and Glen Seaborg in 1950 at the Lawrence Berkeley National Laboratory at the University of California, from which it takes its name. Though it was the sixth transuranic element to be artifically produced in a lab, it does occur naturally in extremely small amounts via the decay cycles of other elements and in fact is the heaviest element for which this is the case; all elements the follow it on the periodic table occur only as a result of artificial synthesis processes. It is a silvery-white actinide metal with moderate chemical reactivity; because its f electrons are further removed from the valence electrons than those of the lighter actinides, it behaves similarly to the lanthanide elements by exhibiting divalent, trivalent, and tetravalent oxidation states in solid-state compounds. It is radioactive and is especially toxic to humans as a result of its natural accumulation in skeletal tissue.

Californium is one of the few transuranic elements with practical applications, a result of its relative stability and strong emission of neutrons. Neutrons penetrate deeply through most materials, and neutron radiography is widely used to detect defects in aircraft and weapons components. Neutrons sourced from californium can also be used to help start up a nuclear reactor, scan nuclear fuel rods, and in radiation therapy for treatment-resistant cervical and brain cancers. Californium is additionally used in the synthesis of other transuranium elements, including ununoctium, which in 2006 became the heaviest element ever synthesized.

Califonium Properties

Californium Bohr ModelCalifornium is a Block F, Group 3, Period 7 element. The number of electrons in each of californium's shells is 2, 8, 18, 32, 28, 8, 2 and its electron configuration is [Rn] 5f10 7s2. The californium atom has a radius of 186.pm. In its elemental form, californium's CAS number is 7440-71-3. Californium was discovered by Stanley G. Thompson, Kenneth Street Jr. and Albert Ghiorso at the Lawrence Berkeley National Laboratory in 1950. The element was named in honor of the state of California and for the University of California, Berkeley, USA. It was the sixth transuranium element of the actinide series to be discovered.

Californium's f electrons are further removed from the valence electrons than those of the lighter actinides so it resembles the behavior of the lanthanide elements by exhibiting divalent, trivalent, and tetravalent oxidation states in solid-state compounds. Because it's a very efficient source of neutrons, many new uses are expected for it.

Californium is radioactive and therefore harmful. Californium information, including technical data, properties, and other useful facts are discussed below. Scientific facts such as the atomic structure, ionization energy, abundance on Earth, conductivity and thermal properties are included.

Symbol: Cf
Atomic Number: 98
Atomic Weight: 251
Element Category: Actinide
Group, Period, Block: n/a, 7, f
Color: silvery-white/ unknown
Other Names: Californio
Melting Point: 900 °C, 1652 °F, 1173.15 K
Boiling Point: 1470 °C,2678 °F, 1743 K (est.)
Density: 15.1 g/cm3
Liquid Density @ Melting Point: N/A
Density @ 20°C: 13.67 g/cm3
Density of Solid: 15100 kg·m3
Specific Heat: N/A
Superconductivity Temperature: N/A
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): N/A
Heat of Vaporization (kJ·mol-1): N/A
Heat of Atomization (kJ·mol-1): 175
Thermal Conductivity: N/A
Thermal Expansion: N/A
Electrical Resistivity: N/A
Tensile Strength: N/A
Molar Heat Capacity: N/A
Young's Modulus: N/A
Shear Modulus: N/A
Bulk Modulus: N/A
Poisson Ratio: N/A
Mohs Hardness: 4-Mar
Vickers Hardness: N/A
Brinell Hardness: N/A
Speed of Sound: N/A
Pauling Electronegativity: 1.3
Sanderson Electronegativity: N/A
Allred Rochow Electronegativity: 1.2
Mulliken-Jaffe Electronegativity: N/A
Allen Electronegativity: N/A
Pauling Electropositivity: 2.7
Reflectivity (%): N/A
Refractive Index: N/A
Electrons: 98
Protons: 98
Neutrons: 153
Electron Configuration: [Rn] 5f10 7s2
Atomic Radius: pm (estimated)
Atomic Radius, non-bonded (Å): 2.45
Covalent Radius: pm (estimated)
Covalent Radius (Å): 1.68
Van der Waals Radius: N/A
Oxidation States: 2, 3, 4
Phase: Solid
Crystal Structure: hexagonal
Magnetic Ordering: N/A
Electron Affinity (kJ·mol-1) Unknown
1st Ionization Energy: 608 kJ·mol-1(estimated)
2nd Ionization Energy: N/A
3rd Ionization Energy: N/A
CAS Number: 7440-71-3
EC Number: N/A
MDL Number: N/A
Beilstein Number: N/A
SMILES Identifier: [Cf]
InChI Identifier: InChI=1S/Cf
InChI Key: HGLDOAKPQXAFKI-UHFFFAOYSA-N
PubChem CID: 23997
ChemSpider ID: 22433
Earth - Total: N/A
Mercury - Total: N/A
Venus - Total: N/A
Earth - Seawater (Oceans), ppb by weight: N/A
Earth - Seawater (Oceans), ppb by atoms: N/A
Earth -  Crust (Crustal Rocks), ppb by weight: N/A
Earth -  Crust (Crustal Rocks), ppb by atoms: N/A
Sun - Total, ppb by weight: N/A
Sun - Total, ppb by atoms: N/A
Stream, ppb by weight: N/A
Stream, ppb by atoms: N/A
Meterorite (Carbonaceous), ppb by weight: N/A
Meterorite (Carbonaceous), ppb by atoms: N/A
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: N/A
Universe, ppb by atom: N/A
Discovered By: Lawrence Berkeley Nat'l Laboratory
Discovery Date: 1950
First Isolation: N/A

Californium Isotopes

Trace quantities of californium are found in nature from neutron capture by uranium atoms; however, the element is mainly produced artificially and has no stable isotopes.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
237Cf 237.06207(54)# 2.1(3) s SF; ß+ to 237Bk; a to 233Cm 5/2+# N/A 1778.415039 -
238Cf 238.06141(43)# 21.1(13) ms SF 0+ N/A 1787.100952 -
239Cf 239.06242(23)# 60(30) s [39(+37-12) s] a to 235Cm; SF; ß+ to 239Bk 5/2+# N/A 1794.083984 -
240Cf 240.06230(22)# 1.06(15) min a to 236Cm; SF; ß+ to 240Bk 0+ N/A 1802.420044 -
241Cf 241.06373(27)# 3.78(70) min ß+ to 241Bk; SF; a to 237Cm 7/2-# N/A 1809.166992 -
242Cf 242.06370(4) 3.49(15) min a to 238Cm; ß+ to 242Bk; SF 0+ N/A 1817.263794 -
243Cf 243.06543(15)# 10.7(5) min ß+ to 243Bk; SF; a to 239Cm (1/2+) N/A 1823.722046 -
244Cf 244.066001(3) 19.4(6) min a to 240Cm; EC to 244Bk; SF 0+ N/A 1831.262451 -
245Cf 245.068049(3) 45.0(15) min ß+ to 245Bk; SF; a to 241Cm (5/2+) N/A 1837.425049 -
246Cf 246.0688053(22) 35.7(5) h a to 242Cm; EC to 246Bk; SF 0+ N/A 1844.789062 -
247Cf 247.071001(9) 3.11(3) h EC to 247Bk; a to 244Cm (7/2+)# N/A 1850.817505 -
248Cf 248.072185(6) 333.5(28) d a to 244Cm; SF 0+ N/A 1857.783936 -
249Cf 249.0748535(24) 351(2) y a to 245Cm; SF 9/2- N/A 1863.369385 -
250Cf 250.0764061(22) 13.08(9) y a to 246Cm; SF 0+ N/A 1869.994019 -
251Cf 251.079587(5) 900(40) y a to 247Cm 1/2+ N/A 1875.103027 -
252Cf 252.081626(5) 2.645(8) y a to 248Cm; SF 0+ N/A 1881.274536 -
253Cf 253.085133(7) 17.81(8) d a to 249Cm; ß- to 253Es (7/2+) N/A 1886.078979 -
254Cf 254.087323(13) 60.5(2) d a to 250Cm; SF 0+ N/A 1892.11084 -
255Cf 255.09105(22)# 85(18) min ß- to 255Es; SF; a to 251Cm (7/2+) N/A 1896.713989 -
256Cf 256.09344(32)# 12.3(12) min SF; ß- to 256Es; a to 252Cm 0+ N/A 1902.54895 -
Californium Elemental Symbol

Recent Research & Development for Californium

  • Design of the injection beamline for the Californium Rare Isotope Breeder Upgrade electron beam ion source charge breeder.. Dickerson CA, Mustapha B, Kondrashev S, Ostroumov PN, Savard G, Levand A, Pikin A.. Rev Sci Instrum. 2012 Feb
  • Operational experience with the Argonne National Laboratory Californium Rare Ion Breeder Upgrade facility and electron cyclotron resonance charge breeder.. Vondrasek R, Clark J, Levand A, Palchan T, Pardo R, Savard G, Scott R.. Rev Sci Instrum. 2014 Feb
  • [Follow-up study of clinical effects of californium-252 neutron intracavitary radiotherapy and external beam radiotherapy in endometrial cancer].. Lei X, Shan JL, Tang C, Zhao KW.. Zhonghua Fu Chan Ke Za Zhi. 2007 Nov
  • Solving the hydration structure of the heaviest actinide aqua ion known: the californium(III) case.. Galbis E, Hernández-Cobos J, den Auwer C, Le Naour C, Guillaumont D, Simoni E, Pappalardo RR, Sánchez Marcos E.. Angew Chem Int Ed Engl. 2010 May 17
  • Results with the electron cyclotron resonance charge breeder for the 252Cf fission source project (Californium Rare Ion Breeder Upgrade) at Argonne Tandem Linac Accelerator System.. Vondrasek R, Kondrashev S, Pardo R, Scott R, Zinkann GP.. Rev Sci Instrum. 2010 Feb
  • [The preliminary report of cervical cancer treated with californium-252 neutron after loading intracavitary radiotherapy].. Luo G, Zheng C, Shan J.. Zhonghua Fu Chan Ke Za Zhi. 2001 Dec
  • Unusual structure, bonding and properties in a californium borate.. Polinski MJ, Garner EB 3rd, Maurice R, Planas N, Stritzinger JT, Parker TG, Cross JN, Green TD, Alekseev EV, Van Cleve SM, Depmeier W, Gagliardi L, Shatruk M, Knappenberger KL, Liu G, Skanthakumar S, Soderholm L, Dixon DA, Albrecht-Schmitt TE.. Nat Chem. 2014 May
  • Californium-252 brachytherapy combined with external-beam radiotherapy for cervical cancer: long-term treatment results.. Lei X, Qian CY, Qing Y, Zhao KW, Yang ZZ, Dai N, Zhong ZY, Tang C, Li Z, Gu XQ, Zhou Q, Feng Y, Xiong YL, Shan JL, Wang D.. Int J Radiat Oncol Biol Phys. 2011 Dec 1
  • Californium gleaming.. Albrecht-Schmitt T.. Nat Chem. 2014 Sep
  • Low-dose-rate californium-252 neutron intracavitary afterloading radiotherapy combined with conformal radiotherapy for treatment of cervical cancer.. Zhang M, Xu HD, Pan SD, Lin S, Yue JH, Liu JR.. Int J Radiat Oncol Biol Phys. 2012 Jul 1