Californium
About Californium

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 Properties
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.
General Properties
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 |
Physical Properties
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 |
Chemical Properties
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 |
Identifiers
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 |
Abundance
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 |
History
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 | - |