Californium (Cf)

Isotopes of Californium 

Isotope Atomic Mass Half-life Mode of Decay Nuclear Spin Nuclear Magnetic Moment
Cf-248 248.07218 334 days α to Cm-244;
0 No data available 
Cf-249  249.07485 351 years α to Cm-245;
9/2 No data available 
Cf-250  250.07640 13.10 years α to Cm-246;
0 No data available 
Cf-251  251.079580 898 years α to Cm-247 1/2 No data available 
Cf-252  252.08162 2.64 years α to Cm-248;
0 No data available 
Cf-253  253.08513 17.80 days α to Cm-249;
ß- to Es-253
7/2 No data available 
Cf-254  254.08732 60.50 days α to Cm-250;
0 No data available 
Cf-255  255.0910 1.40 hours ß- to Es-255 No data available  No data available 



Californium is a radioactive rare earth metal named after the state of California and the University of California at Berkeley, USA, where it was discovered in 1950 by Glenn T. Seaborg, Stanley G. Thompson, Albert Ghiorso and Kenneth Street.

Two crystalline forms exist for californium under normal pressure: one above 900 ºC and one below 900 ºC. A third form exists at high pressure. Californium slowly tarnishes in air at room temperature. Compounds of californium are dominated by a chemical form of the element, designated californium(III), that can participate in three chemical bonds. 

Californium has several practical applications. It can be used to help start up nuclear reactors; as a source of neutrons when studying materials with neutron diffraction and neutron spectroscopy; and in nuclear synthesis of higher-mass elements. 

The isotope Californium-252 is a strong neutron emitter: one microgram emits 170 million neutrons per minute, making it a biological hazard. 

Properties of Californium

Name Californium
Symbol Cf
Atomic number 98
Atomic weight [251]
Standard state Solid at 298 °K
CAS Registry ID 7440-71-3
Group in periodic table N/A
Group name Actinoid
Period in periodic table 7 (Actinoid)
Block in periodic table f-block
Color Unknown, but probably metallic and silvery white or grey in appearance
Classification Metallic
Melting point 1173 °K [or 900 °C or 1652 °F]
Boiling point No data available
Density of solid 15.1 g/cm3
Electron configuration [Rn]5f107s2


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