"the elements directly above them in the periodic table were named. However, the element directly above element 98 in the periodic table, dysprosium, has a name that simply means ""hard to get at"" so the researchers decided to set aside the informal naming convention. They added that ""the best we can do is to point out [that] ... searchers a century ago found it difficult to get to California."" Weighable quantities of californium were first produced by the irradiation of plutonium targets at the Materials Testing Reactor at the National Reactor Testing Station in eastern Idaho; and these findings were"
"9, 1950. It was the sixth transuranium element to be discovered; the team announced its discovery on March 17, 1950. To produce californium, a microgram-sized target of curium-242 () was bombarded with 35 MeV-alpha particles () in the cyclotron at Berkeley, which produced californium-245 () plus one free neutron (). Only about 5,000 atoms of californium were produced in this experiment, and these atoms had a half-life of 44 minutes. The discoverers named the new element after the university and the state. This was a break from the convention used for elements 95 to 97, which drew inspiration from how"
"pressure: one above and one below . A third form exists at high pressure. Californium slowly tarnishes in air at room temperature. Compounds of californium are dominated by the +3 oxidation state. The most stable of californium's twenty known isotopes is californium-251, which has a half-life of 898 years. This short half-life means the element is not found in significant quantities in the Earth's crust. Californium-252, with a half-life of about 2.64 years, is the most common isotope used and is produced at the Oak Ridge National Laboratory in the United States and the Research Institute of Atomic Reactors in"
"Isotopes of californium Californium (Cf) is an artificial element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was Cf in 1950. There are 20 known radioisotopes ranging from Cf to Cf and one nuclear isomer, Cf. The longest-lived isotope is Cf with a half-life of 900 years. Californium-252 (Cf-252) undergoes spontaneous fission and is used in small sized neutron sources. Fission neutrons have an energy range of 0 to 13 MeV with a mean value of 2.3 MeV and a most probable value of"
"Russia. Californium is one of the few transuranium elements that have practical applications. Most of these applications exploit the property of certain isotopes of californium to emit neutrons. For example, californium can be used to help start up nuclear reactors, and it is employed as a source of neutrons when studying materials using neutron diffraction and neutron spectroscopy. Californium can also be used in nuclear synthesis of higher mass elements; oganesson (element 118) was synthesized by bombarding californium-249 atoms with calcium-48 ions. Users of californium must take into account radiological concerns and the element's ability to disrupt the formation of"
"which is similar to trivalent lanthanide metals but smaller than more familiar metals, such as aluminium (70 GPa). Californium exhibits oxidation states of 4, 3, or 2. It typically forms eight or nine bonds to surrounding atoms or ions. Its chemical properties are predicted to be similar to other primarily 3+ valence actinide elements and the element dysprosium, which is the lanthanide above californium in the periodic table. The element slowly tarnishes in air at room temperature, with the rate increasing when moisture is added. Californium reacts when heated with hydrogen, nitrogen, or a chalcogen (oxygen family element); reactions with"
"of 2.645 years. All the remaining isotopes have half-lives shorter than a year, and the majority of these have half-lives shorter than 20 minutes. The isotopes of californium range in mass number from 237 to 256. Californium-249 is formed from the beta decay of berkelium-249, and most other californium isotopes are made by subjecting berkelium to intense neutron radiation in a nuclear reactor. Although californium-251 has the longest half-life, its production yield is only 10% due to its tendency to collect neutrons (high neutron capture) and its tendency to interact with other particles (high neutron cross-section). Californium-252 is a very"
"to obtain microgram amounts of sub-micrometer thick films. Traces of californium can be found near facilities that use the element in mineral prospecting and in medical treatments. The element is fairly insoluble in water, but it adheres well to ordinary soil; and concentrations of it in the soil can be 500 times higher than in the water surrounding the soil particles. Fallout from atmospheric nuclear testing prior to 1980 contributed a small amount of californium to the environment. Californium isotopes with mass numbers 249, 252, 253, and 254 have been observed in the radioactive dust collected from the air after"
"strong neutron emitter, which makes it extremely radioactive and harmful. Californium-252 undergoes alpha decay 96.9% of the time to form curium-248 while the remaining 3.1% of decays are spontaneous fission. One microgram (µg) of californium-252 emits 2.3 million neutrons per second, an average of 3.7 neutrons per spontaneous fission. Most of the other isotopes of californium decay to isotopes of curium (atomic number 96) via alpha decay. Californium was first synthesized at the University of California Radiation Laboratory in Berkeley, by the physics researchers Stanley G. Thompson, Kenneth Street, Jr., Albert Ghiorso, and Glenn T. Seaborg on or about February"
"Copernicium Copernicium is a synthetic chemical element with symbol Cn and atomic number 112. It is an extremely radioactive element, and can only be created in a laboratory. The most stable known isotope, copernicium-285, has a half-life of approximately 29 seconds. Copernicium was first created in 1996 by the GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany. It is named after the astronomer Nicolaus Copernicus. In the periodic table of the elements, copernicium is a d-block transactinide element and a group 12 element. During reactions with gold, it has been shown to be an extremely volatile metal, so"
"elements emit α particles, gamma rays and neutrons. Californium(III) polyborate Californium polyborate is a covalent compound with formula Cf[BO(OH)]. In this compound the californium is in a +3 oxidation state. Californium polyborate is unusual in that californium is covalently bound to the borate. Californium was expected to resemble lanthanide elements in being highly ionic. The polyborate anion is polarisable and flexible. The 5f, 6d, 7s, and 7p orbitals of californium are all involved on the bonding. Most valence electrons are in the 5f orbital, and a significant fraction () in the 6d orbital, and smaller fractions of one electron are"
"a nuclear explosion. Californium is not a major radionuclide at United States Department of Energy legacy sites since it was not produced in large quantities. Californium was once believed to be produced in supernovas, as their decay matches the 60-day half-life of Cf. However, subsequent studies failed to demonstrate any californium spectra, and supernova light curves are now thought to follow the decay of nickel-56. The transuranic elements from americium to fermium, including californium, occurred naturally in the natural nuclear fission reactor at Oklo, but no longer do so. Californium is produced in nuclear reactors and particle accelerators. Californium-250 is"
"bombardment of Cm with neon (Ne), magnesium (Mg), or calcium (Ca) yielded certain isotopes of seaborgium (Sg), hassium (Hs and Hs), and livermorium (Lv, Lv, and possibly Lv). Californium was discovered when a microgram-sized target of curium-242 was irradiated with 35 MeV alpha particles using the cyclotron at Berkeley: Only about 5,000 atoms of californium were produced in this experiment. The most practical application of Cm — though rather limited in total volume — is as α-particle source in the alpha particle X-ray spectrometers (APXS). These instruments were installed on the Sojourner, Mars, Mars 96, Mars Exploration Rovers and Philae"
"Calcium Calcium is a chemical element with symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth's crust and the third most abundant metal, after iron and aluminium. The most common calcium compound on Earth is calcium carbonate, found in limestone and the fossilised remnants of early sea life; gypsum, anhydrite, fluorite, and apatite are also sources of calcium. The"
"of use, reactor start-up (48.3%), fuel rod scanning (25.3%), and activation analysis (19.4%). By 1994 most californium-252 was used in neutron radiography (77.4%), with fuel rod scanning (12.1%) and reactor start-up (6.9%) as important but distant secondary uses. Californium-251 has a very small calculated critical mass of about , high lethality, and a relatively short period of toxic environmental irradiation. The low critical mass of californium led to some exaggerated claims about possible uses for the element. In October 2006, researchers announced that three atoms of oganesson (element 118) had been identified at the Joint Institute for Nuclear Research in"
"sites produce californium-252: the Oak Ridge National Laboratory in the United States, and the Research Institute of Atomic Reactors in Dimitrovgrad, Russia. As of 2003, the two sites produce 0.25 grams and 0.025 grams of californium-252 per year, respectively. Three californium isotopes with significant half-lives are produced, requiring a total of 15 neutron captures by uranium-238 without nuclear fission or alpha decay occurring during the process. Californium-253 is at the end of a production chain that starts with uranium-238, includes several isotopes of plutonium, americium, curium, berkelium, and the californium isotopes 249 to 253 (see diagram). Californium-252 has a number"
"Dubna, Russia, as the product of bombardment of californium-249 with calcium-48, making it the heaviest element ever synthesized. The target for this experiment contained about 10 mg of californium-249 deposited on a titanium foil of 32 cm area. Californium has also been used to produce other transuranium elements; for example, element 103 (later named lawrencium) was first synthesized in 1961 by bombarding californium with boron nuclei. Californium that bioaccumulates in skeletal tissue releases radiation that disrupts the body's ability to form red blood cells. The element plays no natural biological role in any organism due to its intense radioactivity and"
"compounds, since the formation of californium brings not only chemical contamination, but also free-radical effects and self-heating from the emitted alpha particles. Berkelium is a soft, silvery-white, radioactive actinide metal. In the periodic table, it is located to the right of the actinide curium, to the left of the actinide californium and below the lanthanide terbium with which it shares many similarities in physical and chemical properties. Its density of 14.78 g/cm lies between those of curium (13.52 g/cm) and californium (15.1 g/cm), as does its melting point of 986 °C, below that of curium (1340 °C) but higher than"
"Einsteinium Einsteinium is a synthetic element with symbol Es and atomic number 99. A member of the actinide series, it is the seventh transuranic element. Einsteinium was discovered as a component of the debris of the first hydrogen bomb explosion in 1952, and named after Albert Einstein. Its most common isotope einsteinium-253 (half-life 20.47 days) is produced artificially from decay of californium-253 in a few dedicated high-power nuclear reactors with a total yield on the order of one milligram per year. The reactor synthesis is followed by a complex process of separating einsteinium-253 from other actinides and products of their"
"Americium Americium is a synthetic chemical element with symbol Am and atomic number 95. It is radioactive and a transuranic member of the actinide series, in the periodic table located under the lanthanide element europium, and thus by analogy was named after the Americas. Americium was first produced in 1944 by the group of Glenn T. Seaborg from Berkeley, California, at the Metallurgical Laboratory of the University of Chicago, a part of the Manhattan Project. Although it is the third element in the transuranic series, it was discovered fourth, after the heavier curium. The discovery was kept secret and only"
"Californium(III) polyborate Californium polyborate is a covalent compound with formula Cf[BO(OH)]. In this compound the californium is in a +3 oxidation state. Californium polyborate is unusual in that californium is covalently bound to the borate. Californium was expected to resemble lanthanide elements in being highly ionic. The polyborate anion is polarisable and flexible. The 5f, 6d, 7s, and 7p orbitals of californium are all involved on the bonding. Most valence electrons are in the 5f orbital, and a significant fraction () in the 6d orbital, and smaller fractions of one electron are in the 7s and 7p orbitals. Californium(III) polyborate"
"December 1949 by Glenn T. Seaborg, Albert Ghiorso, Stanley G. Thompson, and Kenneth Street, Jr.. They used the 60-inch cyclotron at the University of California, Berkeley. Similar to the nearly simultaneous discovery of americium (element 95) and curium (element 96) in 1944, the new elements berkelium and californium (element 98) were both produced in 1949–1950. The name choice for element 97 followed the previous tradition of the Californian group to draw an analogy between the newly discovered actinide and the lanthanide element positioned above it in the periodic table. Previously, americium was named after a continent as its analogue europium,"
"dry hydrogen and aqueous mineral acids are rapid. Californium is only water-soluble as the californium(III) cation. Attempts to reduce or oxidize the +3 ion in solution have failed. The element forms a water-soluble chloride, nitrate, perchlorate, and sulfate and is precipitated as a fluoride, oxalate, or hydroxide. Californium is the heaviest actinide to exhibit covalent properties, as is observed in the californium borate. Twenty radioisotopes of californium have been characterized, the most stable being californium-251 with a half-life of 898 years, californium-249 with a half-life of 351 years, californium-250 with a half-life of 13.08 years, and californium-252 with a half-life"
"Curium Curium is a transuranic radioactive chemical element with symbol Cm and atomic number 96. This element of the actinide series was named after Marie and Pierre Curie – both were known for their research on radioactivity. Curium was first intentionally produced and identified in July 1944 by the group of Glenn T. Seaborg at the University of California, Berkeley. The discovery was kept secret and only released to the public in November 1947. Most curium is produced by bombarding uranium or plutonium with neutrons in nuclear reactors – one tonne of spent nuclear fuel contains about 20 grams of"
"Fermium Fermium is a synthetic element with symbol Fm and atomic number 100. It is an actinide and the heaviest element that can be formed by neutron bombardment of lighter elements, and hence the last element that can be prepared in macroscopic quantities, although pure fermium metal has not yet been prepared. A total of 19 isotopes are known, with Fm being the longest-lived with a half-life of 100.5 days. It was discovered in the debris of the first hydrogen bomb explosion in 1952, and named after Enrico Fermi, one of the pioneers of nuclear physics. Its chemistry is typical"
"Uranium Uranium is a chemical element with symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weakly radioactive because all isotopes of uranium are unstable, with half-lives varying between 159,200 years and 4.5 billion years. The most common isotopes in natural uranium are uranium-238 (which has 146 neutrons and accounts for over 99%) and uranium-235 (which has 143 neutrons). Uranium has the highest atomic weight of the primordially occurring elements. Its density is"
"It was then officially named by the International Union of Pure and Applied Chemistry (IUPAC) after Nicolaus Copernicus on February 19, 2010, the 537th anniversary of Copernicus' birth. Like in most other d-block groups, the abundance in Earth's crust of group 12 elements decreases with higher atomic number. Zinc is with 65 parts per million (ppm) the most abundant in the group while cadmium with 0.1 ppm and mercury with 0.08 ppm are orders of magnitude less abundant. Copernicium, as a synthetic element with a half-life of a few minutes, may only be present in the laboratories where it was"
"bound to the borate. Californium is the second-heaviest element for which an organometallic compound is known. CpCf (Cp = CH) was prepared from reaction of CpBe and CfCl on microgram scale and characterized by X-ray crystallography. Californium compounds Few compounds of californium have been made and studied. The only californium ion that is stable in aqueous solutions is the californium(III) cation. The other two oxidation states are IV (strong oxidizing agents) and II (strong reducing agents). The element forms a water-soluble chloride, nitrate, perchlorate, and sulfate and is precipitated as a fluoride, oxalate or hydroxide. If problems of availability of"
"Berkelium Berkelium is a transuranic radioactive chemical element with symbol Bk and atomic number 97. It is a member of the actinide and transuranium element series. It is named after the city of Berkeley, California, the location of the Lawrence Berkeley National Laboratory (then the University of California Radiation Laboratory) where it was discovered in December 1949. Berkelium was the fifth transuranium element discovered after neptunium, plutonium, curium and americium. The major isotope of berkelium, Bk, is synthesized in minute quantities in dedicated high-flux nuclear reactors, mainly at the Oak Ridge National Laboratory in Tennessee, USA, and at the Research"
"for modern chemical research and as such, the University has renovated and converted some of the rooms into offices, classrooms, and small research laboratories. Following the FUSRAP remediation work, Gillman Hall has been certified as safe to current radiologic standards. The University of California is responsible for maintenance and monitoring of the shielded contamination. Gilman Hall Gilman Hall is a building on the campus of the University of California, Berkeley. Room 307 was where Glenn T. Seaborg and his coworkers identified plutonium as a new element on February 23, 1941 and as such, is designated a National Historic Landmark. The"
"+3 oxidation states include the sulfide and metallocene. Californium(IV) oxide (black brown, CfO), californium(IV) fluoride (green, CfF) represent the IV oxidation state. The II state is represented by californium(II) bromide (yellow, CfBr) and californium(II) iodide (dark violet, CfI). Californium(IV) oxide (CfO) is a black-brown solid that has a cubic crystal structure with a lattice parameter, the distance between unit cells in the crystal, of 531.0 ± 0.2 pm. Crystals of californium(III) oxide normally have a body-centered cubic symmetry. They convert to a monoclinic form upon heating to about 1400 °C and melt at 1750 °C. Californium(III) chloride (CfCl) is an"
"Livermorium Livermorium is a synthetic chemical element with symbol Lv and has an atomic number of 116. It is an extremely radioactive element that has only been created in the laboratory and has not been observed in nature. The element is named after the Lawrence Livermore National Laboratory in the United States, which collaborated with the Joint Institute for Nuclear Research (JINR) in Dubna, Russia to discover livermorium during experiments made between 2000 and 2006. The name of the laboratory refers to the city of Livermore, California where it is located, which in turn was named after the rancher and"
"of the fifty bombardments contained samples emitting (8.5 ± 0.1) MeV alpha particles, which were in drops which eluted earlier than fermium (atomic number ""Z"" = 100) and californium (""Z"" = 98). The half-life reported was 10 minutes and was assigned to either 102 or 102, although the possibility that the alpha particles observed were from a presumably short-lived mendelevium (""Z"" = 101) isotope created from the electron capture of element 102 was not excluded. The team proposed the name ""nobelium"" (No) for the new element, which was immediately approved by IUPAC, a decision which the Dubna group characterized in"