QUICK REFERENCE
- Symbol: Cf
- Atomic Number: 98
- Atomic Weight: [251]
- Element Classification: Actinide
- Discovered By: Lawrence Berkeley National Laboratory team
- Discovery Date: 1950
- Name Origin: Named after the state of California and the University of California, Berkeley
- Density(g/cc): 15.1
- Melting Point: 900°C
- Boiling Point: 1740°C (estimated)
- Appearance: Silvery-white, radioactive metal
- Atomic Radius(pm): 186 (estimated)
Discovery
Californium was first synthesized on February 9, 1950, by a research team at the Lawrence Berkeley National Laboratory, led by Stanley G. Thompson, Albert Ghiorso, and Glenn T. Seaborg. The element was produced by bombarding a target of curium-242 with alpha particles (helium nuclei) in the 60-inch cyclotron at Berkeley. Californium was the sixth transuranium element to be discovered and was named in honor of the state of California and the University of California, where the element was discovered.
Relation to Other Elements
Californium is part of the actinide series and exhibits characteristics typical of these elements, such as radioactivity and the ability to form multiple oxidation states, with +3 being the most common. Californium-252, one of its most important isotopes, is a strong neutron emitter, which distinguishes it from many other elements and has led to specialized applications.
Natural Occurrence
Californium does not occur naturally on Earth and is produced synthetically in nuclear reactors or particle accelerators.
Uses
Californium has several specialized applications, primarily based on its ability to emit neutrons:
- Neutron Sources: Californium-252 is used in compact neutron sources for neutron activation analysis to detect trace amounts of elements in samples, for oil well logging in the petroleum industry, and in startup neutron sources for some nuclear reactors.
- Medical Uses: Californium-252 is investigated for use in cancer treatment, particularly in neutron therapy, where its neutron emissions are used to kill cancer cells.
- Security and Detection: The intense neutron emission from californium-252 is utilized in devices that scan cargo and luggage for explosives and contraband.
- Scientific Research: Californium is used in research for producing heavier elements and studying the properties of actinides.
The discovery of californium expanded the boundaries of chemistry and physics, contributing to our understanding of the heavy elements. Despite its high cost and radioactivity, californium’s unique properties make it valuable for applications in science, medicine, and security.