Californium

Californium is a <a href="/facts/Synthetic_element/azU9Nr1m">synthetic chemical element</a>; it has <a href="/facts/Chemical_symbol/2Fe1VAL0">symbol</a> Cf and <a href="/facts/Atomic_number/bgAr581S">atomic number</a> 98. It was first synthesized in 1950 at <a href="/facts/Lawrence_Berkeley_National_Laboratory/tvjPSwC9">Lawrence Berkeley National Laboratory</a> (then the University of California Radiation Laboratory) by bombarding <a href="/facts/Curium/LMyWXg8l">curium</a> with <a href="/facts/Alpha_particle/dzNMs9WP">alpha particles</a> (<a href="/facts/Helium-4/vNsL5qhC">helium-4</a> ions). It is an <a href="/facts/Actinide/kHC4lxJV">actinide</a> element, the sixth <a href="/facts/Transuranium_element/a12PwdAw">transuranium element</a> to be <a href="/facts/Synthetic_element/azU9Nr1m">synthesized</a>, and has the second-highest atomic mass of all elements that have been produced in amounts large enough to see with the <a href="/facts/Naked_eye/ePEIa0lK">naked eye</a> (after <a href="/facts/Einsteinium/RePoIVN9">einsteinium</a>). It was named after the university and the <a href="/facts/U.S._state/PFwcRIYQ">U.S. state</a> of <a href="/facts/California/zLW2vdQJ">California</a>.
Two <a href="/facts/Crystal_structure/bJ4bCeHd">crystalline forms</a> exist at normal pressure: one above and one below 900 °C (1,650 °F). A third form exists at high pressure. Californium slowly tarnishes in air at room temperature. <a href="/facts/Californium_compounds/PaHz9EJY">Californium compounds</a> are dominated by the +3 <a href="/facts/Oxidation_state/W53W6s6V">oxidation state</a>. The most stable of californium's twenty known <a href="/facts/Isotope/KD9B1y6o">isotopes</a> is californium-251, with a <a href="/facts/Half-life/kGVH8BAB">half-life</a> of 898 years. This short half-life means the element is not found in significant quantities in the Earth's crust. 252Cf, with a half-life of about 2.645 years, is the most common isotope used and is produced at <a href="/facts/Oak_Ridge_National_Laboratory/Elq84HKF">Oak Ridge National Laboratory</a> (ORNL) in the United States and <a href="/facts/Research_Institute_of_Atomic_Reactors/NMa2AJF0">Research Institute of Atomic Reactors</a> in Russia.
Californium is one of the few transuranium elements with practical uses. Most of these applications exploit the fact that certain <a href="/facts/Isotopes_of_californium/tX06MlFX">isotopes of californium</a> emit <a href="/facts/Neutron/oRCM1geb">neutrons</a>. For example, californium can be used to help start up <a href="/facts/Nuclear_reactor/8xqjIbge">nuclear reactors</a>, and it is used as a source of neutrons when studying materials using <a href="/facts/Neutron_diffraction/fYXAunDW">neutron diffraction</a> and <a href="/facts/Neutron_spectroscopy/ctfGkmtv">neutron spectroscopy</a>. It can also be used in nuclear synthesis of higher mass elements; <a href="/facts/Oganesson/zs5MQDjV">oganesson</a> (element 118) was synthesized by bombarding californium-249 atoms with <a href="/facts/Calcium-48/cqqfNkMY">calcium-48</a> ions. Users of californium must take into account radiological concerns and the element's ability to disrupt the formation of <a href="/facts/Red_blood_cell/Kggpq8Jh">red blood cells</a> by <a href="/facts/Bioaccumulation/KaHzFKnL">bioaccumulating</a> in skeletal tissue.

Californium open-in-new

Californium