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.
Californium 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.
|Group, Period, Block:||n/a, 7, f|
|Melting Point:||900 °C, 1652 °F, 1173.15 K|
|Boiling Point:||1470 °C,2678 °F, 1743 K (est.)|
|Liquid Density @ Melting Point:||N/A|
|Density @ 20°C:||13.67 g/cm3|
|Density of Solid:||15100 kg·m3|
|Heat of Fusion (kJ·mol-1):||N/A|
|Heat of Vaporization (kJ·mol-1):||N/A|
|Heat of Atomization (kJ·mol-1):||175|
|Molar Heat Capacity:||N/A|
|Speed of Sound:||N/A|
|Allred Rochow Electronegativity:||1.2|
|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|
|Electron Affinity (kJ·mol-1)||Unknown|
|1st Ionization Energy:||608 kJ·mol-1(estimated)|
|2nd Ionization Energy:||N/A|
|3rd Ionization Energy:||N/A|
|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|
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; β+ to 237Bk; α to 233Cm||5/2+#||N/A||1778.415039||-|
|239Cf||239.06242(23)#||60(30) s [39(+37-12) s]||α to 235Cm; SF; β+ to 239Bk||5/2+#||N/A||1794.083984||-|
|240Cf||240.06230(22)#||1.06(15) min||α to 236Cm; SF; β+ to 240Bk||0+||N/A||1802.420044||-|
|241Cf||241.06373(27)#||3.78(70) min||β+ to 241Bk; SF; α to 237Cm||7/2-#||N/A||1809.166992||-|
|242Cf||242.06370(4)||3.49(15) min||α to 238Cm; β+ to 242Bk; SF||0+||N/A||1817.263794||-|
|243Cf||243.06543(15)#||10.7(5) min||β+ to 243Bk; SF; α to 239Cm||(1/2+)||N/A||1823.722046||-|
|244Cf||244.066001(3)||19.4(6) min||α to 240Cm; EC to 244Bk; SF||0+||N/A||1831.262451||-|
|245Cf||245.068049(3)||45.0(15) min||β+ to 245Bk; SF; α to 241Cm||(5/2+)||N/A||1837.425049||-|
|246Cf||246.0688053(22)||35.7(5) h||α to 242Cm; EC to 246Bk; SF||0+||N/A||1844.789062||-|
|247Cf||247.071001(9)||3.11(3) h||EC to 247Bk; α to 244Cm||(7/2+)#||N/A||1850.817505||-|
|248Cf||248.072185(6)||333.5(28) d||α to 244Cm; SF||0+||N/A||1857.783936||-|
|249Cf||249.0748535(24)||351(2) y||α to 245Cm; SF||9/2-||N/A||1863.369385||-|
|250Cf||250.0764061(22)||13.08(9) y||α to 246Cm; SF||0+||N/A||1869.994019||-|
|251Cf||251.079587(5)||900(40) y||α to 247Cm||1/2+||N/A||1875.103027||-|
|252Cf||252.081626(5)||2.645(8) y||α to 248Cm; SF||0+||N/A||1881.274536||-|
|253Cf||253.085133(7)||17.81(8) d||α to 249Cm; β- to 253Es||(7/2+)||N/A||1886.078979||-|
|254Cf||254.087323(13)||60.5(2) d||α to 250Cm; SF||0+||N/A||1892.11084||-|
|255Cf||255.09105(22)#||85(18) min||β- to 255Es; SF; α to 251Cm||(7/2+)||N/A||1896.713989||-|
|256Cf||256.09344(32)#||12.3(12) min||SF; β- to 256Es; α to 252Cm||0+||N/A||1902.54895||-|
Recent Research & Development for Californium
- Californium-252 Plasma Desorption Mass Spectrometry. R. D. Macfarlane. Anal. Chem.
- Dehalogenation reactions in californium-252 plasma desorption mass spectrometry. Yi Ming Yang, Henry M. Fales, Lewis Pannell. Anal. Chem.
- Californium-252 plasma desorption mass spectrometry of oligosaccharides and glycoconjugates: control of ionization and fragmentation. Subhodaya Aduru, Brian T. Chait. Anal. Chem.
- Pulse radiolysis studies of californium(III) in aqueous perchlorate solution. Evidence for the preparation of californium(II). J. C. Sullivan, L. R. Morss, K. H. Schmidt, W. A. Mulac, S. Gordon. Inorg. Chem.
- Characterization of coal liquefaction heavy products using californium-252 plasma desorption mass spectrometry. John W. Larsen, Andrzej R. Lapucha, Patrick C. Wernett, William R. Anderson. Energy Fuels
- Surface characterization of a National Bureau of Standards glass reference material by californium-252 particle desorption mass spectrometry. W. R. Summers, M. U. D. Beug-Deeb, E. A. Schweikert. Anal. Chem.
- Transformation of monoclinic californium bromide to orthorhombic CfBr3 by the application of pressure. J. R. Peterson, J. P. Young, R. G. Haire, G. M. Begun, U. Benedict. Inorg. Chem.
- Absorption spectrophotometric and x-ray diffraction studies of the trichlorides of berkelium-249 and californium-249. J. R. Peterson, J. P. Young, D. D. Ensor, R. G. Haire. Inorg. Chem.
- Separation of Methyl Violet 2B by high-speed countercurrent chromatography and identification by californium-252 plasma desorption mass spectrometry. Henry M. Fales, Lewis K. Pannell, Edward A. Sokoloski, Peter Carmeci. Anal. Chem.
- Californium-252 plasma desorption mass spectrometry of cationic, anionic, and neutral dyes. Lewis K. Pannell, Edward A. Sokoloski, Henry M. Fales, Ramon L. Tate. Anal. Chem.
- Californium-252 plasma desorption mass spectrometry of gold clusters: fragmentation patterns in small clusters and differences in sample composition in large clusters. C. J. McNeal, J. M. Hughes, L. H. Pignolet, L. T. J. Nelson, T. G. Gardner, J. P. Fackler Jr., R. E. P. Winpenny, L. H. Irgens, G. Vigh, R. D. Macfarlane. Inorg. Chem.