Californium
actinideProperties
| Property | Value |
|---|---|
| Atomic Mass | 251 amu |
| Category | actinide |
| Period | 7 |
| Electron Configuration | [Rn] 5f10 7s2 |
| Electronegativity | 1.3 (Pauling) |
| Oxidation States | 4, 3 |
| Melting Point | 1173 K (899.9 °C) |
| Boiling Point | 1743 K (1469.8 °C) |
| Density | 15.1 g/cm³ |
| Discovered By | Glenn T. Seaborg, Albert Ghiorso, Stanley G. Thompson, Kenneth Street Jr. (1950) |
About Californium
Californium is the only transuranium element with a real industrial market, and it earned that market by being the most concentrated source of neutrons humans can put in a steel pencil. Cf-252 spontaneously fissions about 3% of the time it decays, throwing off roughly 2.3 × 10¹² neutrons per second per gram with an average energy of 2.1 MeV. A microgram fits on the head of a pin and lights up a moisture-density gauge or a fission counter brightly enough to see oil sands logging while drilling. Glenn Seaborg's group made the first 5,000 atoms in 1950 by alpha-bombarding ²⁴²Cm in the Berkeley 60-inch cyclotron, and the Department of Energy has produced Cf-252 in milligram quantities at the High Flux Isotope Reactor at Oak Ridge ever since — by long-chain neutron capture starting from curium targets, which is why the price hovers around $27 million per gram. The chemistry follows the trivalent actinide pattern: Cf³⁺ in solution, soluble fluorides, sesquioxide, behavior that closely mirrors dysprosium's.
Fun Fact
A single microgram of Cf-252 emits about 2.3 million neutrons per second — enough to startup-test a commercial power reactor, but small enough to ship in a pencil-sized capsule.
Common Uses
- Cf-252 neutron startup sources for commercial power reactors
- Neutron well-logging gauges for oilfield porosity and moisture surveys
- Prompt gamma neutron activation analysis for explosives and contraband
- Cf-252 brachytherapy seeds for cervical and brain tumors
- Cf-249 targets used at JINR Dubna to synthesize tennessine