Californium - Cf General Information Discovery Californium was discovered by S.G. Thompson, K. Street, A. Ghiorso and G.T.Seaborg in 1950 in California, USA. Appearance Californium is a radioactive, silvery metal. Source Californium did not exist in weighable amounts until ten years after its discovery. The usual method of preparation, producing milligram amounts only, is by neutron bombardment of plutonium. Uses Californium is a very strong neutron emitter. It is therefore used as a portable neutron source for the discovery of metals such as gold and silver. One isotope, 252Cf, is used in cancer therapy. Biological Role Californium has no known biological role. It is toxic due to its radioactivity. General Information Californium is attacked by oxygen, steam and acids, but not by alkalis.

	Physical Information
	Atomic Number		98
	Relative Atomic Mass (12C=12.000)		251 (radioactive)
	Melting Point/K		not available
	Boiling Point/K		not available
	Density/kg m-3		not available
	Ground State Electron Configuration		[Rn]5f107s2
	Electron Affinity(M-M-)/kJ mol-1		not available

	Key Isotopes
	nuclide	249Cf	251Cf	252Cf
	atomic mass	249.07
	natural abundance	0%	0%	0%
	half-life	360 yrs	900 yrs	2.65 yrs

Other Information
Enthalpy of Fusion/kJ mol-1		n/a
Enthalpy of Vaporisation/kJ mol-1		n/a
Oxidation States
main	Cf+3
others	Cf+2, Cf+4

	Ionisation Energies/kJ mol-1
	M - M+	608
	M+ - M2+
	M2+ - M3+
	M3+ - M4+
	M4+ - M5+
	M5+ - M6+
	M6+ - M7+
	M7+ - M8+
	M8+ - M9+
	M9+ - M10+