Science, Tech, Math › Science Californium Facts Chemical & Physical Properties of Californium Share Flipboard Email Print Electron configuration of a californium atom. GregRobson/CC BY-SA 2.0 UK/Wikimedia Commons Science Chemistry Periodic Table Basics Chemical Laws Molecules Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated July 22, 2018 Californium is a radioactive rare earth element that can be used as a neutron source. Atomic Number: 98Symbol: CfAtomic Weight: 251.0796Discovery: G.T. Seaborg, S.G. Tompson, A. Ghiorso, K. Street Jr. 1950 (United States)Word Origin: State and University of California Properties: Californium metal has not been produced. Californium (III) is the only ion stable in aqueous solutions. Attempts to reduce or oxidize californium (III) have been unsuccessful. Californium-252 is a very strong neutron emitter. Uses: Californium is an efficient neutron source. It is used in neutron moisture gauges and as a portable neutron source for metal detection. Isotopes: The isotope Cf-249 results from the beta decay of Bk-249. Heavier isotopes of californium are produced by intense neutron irradiation by the reactions. Cf-249, Cf-250, Cf-251, and Cf-252 have been isolated. Sources: Californium was first produced in 1950 by bombarding Cm-242 with 35 MeV helium ions. Electron Configuration [Rn] 7s2 5f10 Californium Physical Data Element Classification: Radioactive Rare Earth (Actinide)Density (g/cc): 15.1Melting Point (K): 900Atomic Radius (pm): 295Pauling Negativity Number: 1.3First Ionizing Energy (kJ/mol): (610)Oxidation States: 4, 3 References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange's Handbook of Chemistry (1952), CRC Handbook of Chemistry & Physics (18th Ed.)