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Chemical, physical and material properties and data of the chemical element Californium.



Californium, a late actinide with twenty known isotopes, is a man-made transuranium chemical element that does not occur naturally. It was first identified by Glenn Seaborg and his co-workers in February 1950 in an experiment that used a 60-inch cyclotron to bombard curium isotope Cm242 with helium ions:

24296Cm + 42He → 24598Cf + 10n.

Although primarily named for the state of California, it also honors the University of California at Berkeley where many elements were first discovered.


General Information about Californium

Regular nameCaliforniumChemical symbolCfOther namesElement 98Systematic nameHistorical namesAccretium, Cyclonium, Cyclotronium, Enactinium, Enneactinium, Euprosium, Lewisium, Nonactinium, Praedicium, Radlabium (all rejected proposals)Name meaning, originCalifornia (US state, location of the research facility)Discovery (year)(1950) - California Radiation Laboratory, Berkeley (Stanley Gerald Thompson, Kenneth Street Jr., Albert Ghiorso, Glenn T. Seaborg)OccurenceOnly artificially producible chemical element.Position in the PSEPeriod 7, f-block, actinoidsGroup membershipTransuranium element


Atomar Properties of Californium

Atomic number Z98 = number of protonsStandard Atomic Weight251.079589428


Electron configuration of Californium


Abbreviated form: [Rn] 5f10 7s2 .


Ionization Energies of Californium

The following table lists the ionization energies IE (ionization potentials); the IE is the energy required in electron volts (eV) per atom to separate a given electron from an Californium atom.



Isotopic Data of Californium

An overview of the nuclides as well as the isotopic data and properties are listed on the following page: Californium isotopes.


Chemistry of Californium


Oxidation states+II. +III. +IV. +VElectronegativity1.3 (Pauling original)
1.30 (Pauling)
Electron affinity-1.01 eV
-97.31 kJ mol-1


Material and Physical Properties

The following table lists some calculated or experimentally determined physical data or material properties of californium.

Melting point900 °CBoiling point1470 °CDensity15.1 g cm-3


Use of Californium

The element has a certain practical importance in the form of the isotope californium-252, which is used in various areas as a neutron source.


External Data, Identifiers

CAS registry number7440-71-3InChI =1S/CfInChIKeyHGLDOAKPQXAFKI-UHFFFAOYSA-NPubChem ID23997


Literature Sources and References

[1] - S. G. Thomson:
New element californium (atomic number 98).
In: OSTI Technical Report, (1950), DOI https://www.osti.gov/biblio/381639.

[2] - Thomas Albrecht-Schmitt:
Californium gleaming.
In: Nature Chemistry, (2014), DOI 10.1038/nchem.2035.

[3] - Samantha K. Cary, Monica Vasiliu, Ryan E. Baumbach et al.:
Emergence of californium as the second transitional element in the actinide series.
In: Nature Communications, (2015), DOI 10.1038/ncomms7827.


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Last update: 2022-12-05

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