Fermium

Not to be confused with "Ferrum", the Latin name for Iron.

einsteinium ← fermium → mendelevium Er ↑ Fm ↓ (Upn) 100Fm Periodic table
Appearance
unknown
General properties
Name, symbol, number	fermium, Fm, 100
Pronunciation	/ˈfɜrmiəm/ fer-mee-əm
Element category	actinide
Group, period, block	n/a, 7, f
Standard atomic weight	(257)
Electron configuration	[Rn] 5f12 7s2
Electrons per shell	2, 8, 18, 32, 30, 8, 2 (Image)
Physical properties
Phase	solid
Melting point	1800 K, 1527 °C, 2781 °F
Atomic properties
Oxidation states	2, 3
Electronegativity	1.3 (Pauling scale)
Ionization energies	1st: 627 kJ·mol−1
Miscellanea
CAS registry number	7440-72-4
Most stable isotopes
Main article: Isotopes of fermium
iso NA half-life DM DE (MeV) DP 252Fm syn 25.39 h SF - - α 7.153 248Cf 253Fm syn 3 d ε 0.333 253Es α 7.197 249Cf 255Fm syn 20.07 h SF - - α 7.241 251Cf 257Fm syn 100.5 d α 6.864 253Cf SF - -
v ·  /ˈfɜrmiəm/ fur-mee-əm) is a synthetic element with the symbol Fm. It is the 100th element in the periodic table and a member of the actinide series. It is 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 fermium metal has not yet been prepared.[1] A total of 19 isotopes are known, with 257Fm being the longest-lived one 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 Nobel laureate Enrico Fermi, one of the pioneers of nuclear physics. Its chemistry is typical of the late actinides, with a preponderance of the +3 oxidation state but also an accessible +2 oxidation state. Owing to the small amounts of produced fermium and its short half-life, there are currently no uses for it outside of basic scientific research. Like all synthetic elements, isotopes of fermium are extremely radioactive and are considered highly toxic. Discovery Fermium was first observed in the fallout from the Ivy Mike nuclear test. The element was named after Enrico Fermi. Fermium was first discovered in the fallout from the 'Ivy Mike' nuclear test (1 November 1952), the first successful test of a hydrogen bomb.[2][3][4] Initial examination of the debris from the explosion had shown the production of a new isotope of plutonium, 244 94Pu: this could only have formed by the absorption of six neutrons by a uranium-238 nucleus followed by two β− decays. At the time, the absorption of neutrons by a heavy nucleus was thought to be a rare process, but the identification of 244 94Pu raised the possibility that still more neutrons could have been absorbed by the uranium nuclei, leading to new elements.[4] Element 99 (einsteinium) was quickly discovered on filter papers which had been flown through the cloud from the explosion (the same sampling technique that had been used to discover 244 94Pu).[4] It was then identified in December 1952 by Albert Ghiorso and co-workers at the University of California at Berkeley.[2][3][4] They discovered the isotope 253Es (half-life 20.5 days) that was made by the capture of 15 neutrons by uranium-238 nuclei – which then underwent seven successive beta decays: $\mathrm{^{238}_{\ 92}U\ \xrightarrow {+\ 15 n} \ ^{253}_{\ 92}U\ \xrightarrow{7 \beta^-} \ ^{253}_{\ 99}Es}$ Some 238U atoms, however, could capture another amount of neutrons (most likely, 16 or 17). The discovery of fermium (Z = 100) required more material, as the yield was expected to be at least an order of magnitude lower than that of element 99, and so contaminated coral from the Enewetak atoll (where the test had taken place) was shipped to the University of California Radiation Laboratory in Berkeley, California, for processing and analysis. About two months after the test, a new component was isolated emitting high-energy α-particles (7.1 MeV) with a half-life of about a day. With such a short half-life, it could only arise from the β− decay of an isotope of einsteinium, and so had to be an isotope of the new element 100: it was quickly identified as 255Fm (t½ = 20.07(7) hours).[4] The discovery of the new elements, and the new data on neutron capture, was initially kept secret on the orders of the U.S. military until 1955 due to Cold War tensions.[4][5][6] Nevertheless, the Berkeley team were able to prepare elements 99 and 100 by civilian means, through the neutron bombardment of plutonium-239, and published this work in 1954 with the disclaimer that it was not the first studies that had been carried out on the elements.[7][8] The 'Ivy Mike' studies were declassified and published in 1955.[5] The Berkeley team had been worried that another group might discover lighter isotopes of element 100 through ion bombardment techniques before they could publish their classified research,[4] and this proved to be the case. A group at the Nobel Institute for Physics in Stockholm independently discovered the element, producing an isotope later confirmed to be 250Fm (t½ = 30 minutes) by bombarding a 238 92U target with oxygen-16 ions, and published their work in May 1954.[9] Nevertheless, the priority of the Berkeley team was generally recognized, and with it the prerogative to name the new element in honour of the recently deceased Enrico Fermi, the developer of the first artificial self-sustained nuclear reactor. Isotopes Main article: Isotopes of fermium Decay pathway of fermium-257 There are 19 isotopes of fermium listed in NUBASE 2003,[10] with atomic weights of 242 to 260,[Note 1] of which 257Fm is the longest-lived with a half-life of 100.5 days. 253Fm has a half-life of 3 days, while 251Fm of 5.3 h, 252Fm of 25.4 h, 254Fm of 3.2 h, 255Fm of 20.1 h, and 256Fm of 2.6 hours. All the remaining ones have half-lives ranging from 30 minutes to less than a millisecond.[10] The neutron-capture product of fermium-257, 258Fm, undergoes spontaneous fission with a half-life of just 370(14) microseconds; 259Fm and 260Fm are also unstable with respect to spontaneous fission (t½ = 1.5(3) s and 4 ms respectively).[10][Note 1] This means that neutron capture cannot be used to create nuclides with a mass number greater than 257, unless carried out in a nuclear explosion. As 257Fm is an α-emitter, decaying to 253Cf, fermium is also the last element that can be prepared by a neutron-capture process.[1][11] Production The High Flux Isotope Reactor at Oak Ridge National Laboratory is one of the places where fermium is produced. Elution: chromatographic separation of Fm(100), Es(99), Cf, Bk, Cm and Am. Fermium is produced by the bombardment of lighter actinides with neutrons in a nuclear reactor. Fermium-257 is the heaviest isotope that is obtained via neutron capture, and can only be produced in nanogram quantities.[Note 2][12] The major source is the 85 MW High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory in Tennessee, USA, which is dedicated to the production of transcurium (Z > 96) elements.[13] In a "typical processing campaign" at Oak Ridge, tens of grams of curium are irradiated to produce decigram quantities of californium, milligram quantities of berkelium and einsteinium and picogram quantities of fermium.[14] However, nanogram[15] and microgram[11] quantities of fermium can be prepared for specific experiments. The quantities of fermium produced in 20–200 kiloton thermonuclear explosions is believed to be of the order of milligrams, although it is mixed in with a huge quantity of debris; 40 picograms of 257Fm was recovered from 10 kilograms of debris from the 'Hutch' test (16 July 1969).[16] After production, the fermium must be separated from other actinides and from lanthanoid fission products. This is usually achieved by ion exchange chromatography, with the standard process using a cation exchanger such as Dowex 50 or TEVA eluted with a solution of ammonium α-hydroxyisobutyrate.[1][17] Smaller cations form more stable complexes with the α-hydroxyisobutyrate anion, and so are preferentially eluted from the column.[1] A rapid fractional crystallization method has also been described.[1][18] Although the most stable isotope of fermium is 257Fm, with a half-life of 100.5 days, most studies are conducted on 255Fm (t½ = 20.07(7) hours) as this isotope can be easily isolated as required as the decay product of 255Es (t½ = 39.8(12) days).[1] Synthesis in nuclear explosions The analysis of the debris at the 10-megaton Ivy Mike nuclear test was a part of long-term project, one of the goals of which was studying the efficiency of production of transuranium elements in high-power nuclear explosions. The motivation for these experiments was as follows: synthesis of such elements from uranium requires multiple neutron capture. The probability of such events increases with the neutron flux, and nuclear explosions are the most powerful neutron sources, providing densities of the order 1023 neutrons/cm² within a microsecond, i.e. about 1029 neutrons/(cm²·s). In comparison, the flux of the HFIR reactor is 5×1015 neutrons/(cm²·s). A dedicated laboratory was set up right at Enewetak Atoll for preliminary analysis of debris, as some isotopes could have decayed by the time the debris samples reached the U.S. The laboratory was receiving samples for analysis, as soon as possible, from airplanes equipped with paper filters which flew over the atoll after the tests. Whereas it was hoped to discover new chemical elements heavier than fermium, those were not found after a series of megaton explosions conducted between 1954 and 1956 at the atoll.[19] Estimated yield of transuranium elements in the U.S. nuclear tests Hutch and Cyclamen.[20] The atmospheric results were supplemented by the underground test data accumulated in the 1960s at the Nevada Test Site, as it was hoped that powerful explosions conducted in confined space might result in improved yields and heavier isotopes. Apart from traditional uranium charges, combinations of uranium with americium and thorium have been tried, as well as a mixed plutonium-neptunium charge. They were less successful in terms of yield that was attributed to stronger losses of heavy isotopes due to enhanced fission rates in heavy-element charges. Isolation of the products was found to be rather problematic, as the explosions were spreading debris through melting and vaporizing rocks under the great depth of 300–600 meters, and drilling to such depth in order to extract the products was both slow and inefficient in terms of collected volumes.[19][20] Among the nine underground tests, which were carried between 1962 and 1969 and codenamed Anacostia (5.2 kilotons, 1962), Kennebec (<5 kilotons, 1963), Par (38, kilotons, 1964), Barbel (<20 kilotons, 1964), Tweed (<20 kilotons, 1965), Cyclamen (13 kilotons, 1966), Kankakee (20-200 kilotons, 1966), Vulcan (25 kilotons, 1966) and Hutch (20-200 kilotons, 1969),[21] the last one was most powerful and had the highest yield of transuranium elements. In the dependence on the atomic mass number, the yield showed a saw-tooth behavior with the lower values for odd isotopes, due to their higher fission rates.[20] The major practical problem of the entire proposal was however collecting the radioactive debris dispersed by the powerful blast. Aircraft filters adsorbed only about 4×10−14 of the total amount and collection of tons of corals at Enewetak Atoll increased this fraction by only two orders of magnitude. Extraction of about 500 kilograms of underground rocks 60 days after the Hutch explosion recovered only about 10−7 of the total charge. The amount of transuranium elements in this 500-kg batch was only 30 times higher than in a 0.4 kg rock picked up 7 days after the test. This observation demonstrated the highly nonlinear dependence of the transuranium elements yield on the amount of retrieved radioactive rock.[22] In order to accelerate sample collection after explosion, shafts were drilled at the site not after but before the test, so that explosion would expel radioactive material from the epicenter, through the shafts, to collecting volumes near the surface. This method was tried in the Anacostia and Kennebec tests and instantly provided hundreds kilograms of material, but with actinide concentration 3 times lower than in samples obtained after drilling; whereas such method could have been efficient in scientific studies of short-lived isotopes, it could not improve the overall collection efficiency of the produced actinides.[23] Although no new elements (apart from einsteinium and fermium) could be detected in the nuclear test debris, and the total yields of transuranium elements were disappointingly low, these tests did provide significantly higher amounts of rare heavy isotopes than previously available in laboratories. So 6×109 atoms of 257Fm could be recovered after the Hutch detonation. They were then used in the studies of thermal-neutron induced fission of 257Fm and in discovery of a new fermium isotope 258Fm. Also the rare 250Cm isotope was synthesized in large quantities, which is very difficult to produce in nuclear reactors from its progenitor 249Cm – the half-life of 249Cm (64 minutes) is much too short for months-long reactor irradiations, but is very "long" on the explosion timescale.[24] Chemistry A fermium-ytterbium alloy used for measuring the enthalpy of vaporization of fermium metal. The chemistry of fermium has only been studied in solution using tracer techniques, and no solid compounds have been prepared. Under normal conditions, fermium exists in solution as the Fm3+ ion, which has a hydration number of 16.9 and an acid dissociation constant of 1.6×10−4 (pKa = 3.8).[25][26] Fermium(3+) forms complexes with a wide variety of organic ligands with hard donor atoms such as oxygen, and these complexes are usually more stable than those of the preceding actinides.[1] It also forms anionic complexes with ligands such as chloride or nitrate and, again, these complexes appear to be more stable than those formed by einsteinium or californium.[27] It is believed that the bonding in the complexes of the later actinides is mostly ionic in character: the Fm3+ ion is expected to be smaller than the preceding An3+ ions because of the higher effective nuclear charge of fermium, and hence fermium would be expected to form shorter and stronger metal–ligand bonds.[1] Fermium(III) can be fairly easily reduced to fermium(II),[28] for example with samarium(II) chloride, with which fermium coprecipitates.[29][30] The electrode potential has been estimated to be similar to that of the ytterbium(III)/(II) couple, or about −1.15 V with respect to the standard hydrogen electrode,[31] a value which agrees with theoretical calculations.[32] The Fm2+/Fm0 couple has an electrode potential of −2.37(10) V based on polarographic measurements.[33] Toxicity Although few people come in contact with fermium, the International Commission on Radiological Protection has set annual exposure limits for the two most stable isotopes. For fermium-253, the ingestion limit was set at 107 Becquerels (1 Bq is equivalent to one decay per second), and the inhalation limit at 105 Bq; for fermium-257, at 105 Bq and 4000 Bq respectively.[34] Notes and references Notes ^ a b The discovery of 260Fm is considered "unproven" in NUBASE 2003.[10] ^ All isotopes of elements Z > 100 can only be produced by accelerator-based nuclear reactions with charged particles and can be obtained only in tracer quantities (e.g., 1 million atoms for Md (Z = 101) per hour of irradiation (see reference 1 below)). References ^ a b c d e f g h Silva, Robert J. (2006). "Fermium, Mendelevium, Nobelium, and Lawrencium". In Morss, Lester R.; Edelstein, Norman M.; Fuger, Jean (PDF). The Chemistry of the Actinide and Transactinide Elements. 3 (3rd ed.). Dordrecht: Springer. pp. 1621–1651. doi:10.1007/1-4020-3598-5_13. http://radchem.nevada.edu/classes/rdch710/files/Fm%20to%20Lr.pdf.  ^ a b "Einsteinium". http://periodic.lanl.gov/elements/99.html. Retrieved 2007-12-07.  ^ a b Fermium – National Research Council Canada. Retrieved 2 December 2007 ^ a b c d e f g Ghiorso, Albert (2003). "Einsteinium and Fermium". Chemical and Engineering News 81 (36). http://pubs.acs.org/cen/80th/einsteiniumfermium.html.  ^ a b Ghiorso, A.; Thompson, S.; Higgins, G.; Seaborg, G.; Studier, M.; Fields, P.; Fried, S.; Diamond, H. et al. (1955). "New Elements Einsteinium and Fermium, Atomic Numbers 99 and 100". Phys. Rev. 99 (3): 1048–1049. Bibcode 1955PhRv...99.1048G. doi:10.1103/PhysRev.99.1048.  ^ Fields, P. R.; Studier, M. H.; Diamond, H.; Mech, J. F.; Inghram, M. G. Pyle, G. L.; Stevens, C. M.; Fried, S.; Manning, W. M. (Argonne National Laboratory, Lemont, Illinois); Ghiorso, A.; Thompson, S. G.; Higgins, G. H.; Seaborg, G. T. (University of California, Berkeley, California): "Transplutonium Elements in Thermonuclear Test Debris", in: Fields, P.; Studier, M.; Diamond, H.; Mech, J.; Inghram, M.; Pyle, G.; Stevens, C.; Fried, S. et al. (1956). "Transplutonium Elements in Thermonuclear Test Debris". Physical Review 102: 180. Bibcode 1956PhRv..102..180F. doi:10.1103/PhysRev.102.180.  ^ Thompson, S. G.; Ghiorso, A.; Harvey, B. G.; Choppin, G. R. (1954). "Transcurium Isotopes Produced in the Neutron Irradiation of Plutonium". Physical Review 93 (4): 908. Bibcode 1954PhRv...93..908T. doi:10.1103/PhysRev.93.908.  ^ Choppin, G. R.; Thompson, S. G.; Ghiorso, A.; Harvey, B. G. (1954). "Nuclear Properties of Some Isotopes of Californium, Elements 99 and 100". Physical Review 94 (4): 1080–1081. Bibcode 1954PhRv...94.1080C. doi:10.1103/PhysRev.94.1080.  ^ Atterling, Hugo; Forsling, Wilhelm; Holm, Lennart W.; Melander, Lars; Åström, Björn (1954). "Element 100 Produced by Means of Cyclotron-Accelerated Oxygen Ions". Physical Review 95 (2): 585–586. Bibcode 1954PhRv...95..585A. doi:10.1103/PhysRev.95.585.2.  ^ a b c d Audi, G.; Bersillon, O.; Blachot, J.; Wapstra, A. H. (2003), "The NUBASE evaluation of nuclear and decay properties", Nucl. Phys. A 729: 3–128, Bibcode 2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001, http://amdc.in2p3.fr/nubase/Nubase2003.pdf  ^ a b Greenwood, Norman N.; Earnshaw, A. (1984). Chemistry of the Elements. Oxford: Pergamon. p. 1262. ISBN 0-08-022057-6.  ^ Luig, Heribert; Keller, Cornelius; Wolf, Walter; Shani, Jashovam; Miska, Horst; Zyball, Alfred; Gervé, Andreas; Balaban, Alexandru T. et al. (2000). Radionuclides. doi:10.1002/14356007.a22_499.  ^ "High Flux Isotope Reactor". Oak Ridge National Laboratory. http://neutrons.ornl.gov/facilities/HFIR/. Retrieved 2010-09-23.  ^ Porter, C. E.; Riley, F. D., Jr.; Vandergrift, R. D.; Felker, L. K. (1997). "Fermium Purification Using Teva™ Resin Extraction Chromatography". Sep. Sci. Technol. 32 (1–4): 83–92. doi:10.1080/01496399708003188.  ^ Sewtz, M.; Backe, H.; Dretzke, A.; Kube, G.; Lauth, W.; Schwamb, P.; Eberhardt, K.; Grüning, C. et al. (2003). "First Observation of Atomic Levels for the Element Fermium (Z = 100)". Phys. Rev. Lett. 90 (16): 163002. Bibcode 2003PhRvL..90p3002S. doi:10.1103/PhysRevLett.90.163002.  ^ Hoff, R. W.; Hulet, E. K. (1970). Engineering with Nuclear Explosives. 2. pp. 1283–1294.  ^ Choppin, G. R.; Harvey, B. G.; Thompson, S. G. (1956). "A new eluant for the separation of the actinide elements". J. Inorg. Nucl. Chem. 2 (1): 66–68. doi:10.1016/0022-1902(56)80105-X.  ^ Mikheev, N. B.; Kamenskaya, A. N.; Konovalova, N. A.; Rumer, I. A.; Kulyukhin, S. A. (1983). "High-speed method for the separation of fermium from actinides and lanthanides". Radiokhimiya 25 (2): 158–161.  ^ a b Seaborg, p. 39 ^ a b c Seaborg, p. 40 ^ United States Nuclear Tests July 1945 through September 1992, DOE/NV--209-REV 15, December 2000 ^ Seaborg, p. 43 ^ Seaborg, p. 44 ^ Seaborg, p. 47 ^ Lundqvist, Robert; Hulet, E. K.; Baisden, T. A.; Näsäkkälä, Elina; Wahlberg, Olof (1981). "Electromigration Method in Tracer Studies of Complex Chemistry. II. Hydrated Radii and Hydration Numbers of Trivalent Actinides". Acta Chem. Scand., Ser. A 35: 653–661. doi:10.3891/acta.chem.scand.35a-0653.  ^ Hussonnois, H.; Hubert, S.; Aubin, L.; Guillaumont, R.; Boussieres, G. (1972). Radiochem. Radioanal. Lett. 10: 231–238.  ^ Thompson, S. G.; Harvey, B. G.; Choppin, G. R.; Seaborg, G. T. (1954). "Chemical Properties of Elements 99 and 100". J. Am. Chem. Soc. 76 (24): 6229–6236. doi:10.1021/ja01653a004.  ^ Malý, Jaromír (1967). "The amalgamation behaviour of heavy elements 1. Observation of anomalous preference in formation of amalgams of californium, einsteinium, and fermium". Inorg. Nucl. Chem. Lett. 3 (9): 373–381. doi:10.1016/0020-1650(67)80046-1.  ^ Mikheev, N. B.; Spitsyn, V. I.; Kamenskaya, A. N.; Gvozdec, B. A.; Druin, V. A.; Rumer, I. A.; Dyachkova, R. A.; Rozenkevitch, N. A. et al. (1972). "Reduction of fermium to divalent state in chloride aqueous ethanolic solutions". Inorg. Nucl. Chem. Lett. 8 (11): 929–936. doi:10.1016/0020-1650(72)80202-2.  ^ Hulet, E. K.; Lougheed, R. W.; Baisden, P. A.; Landrum, J. H.; Wild, J. F.; Lundqvist, R. F. (1979). "Non-observance of monovalent Md". J. Inorg. Nucl. Chem. 41 (12): 1743–1747. doi:10.1016/0022-1902(79)80116-5.  ^ Mikheev, N. B.; Spitsyn, V. I.; Kamenskaya, A. N.; Konovalova, N. A.; Rumer, I. A.; Auerman, L. N.; Podorozhnyi, A. M. (1977). "Determination of oxidation potential of the pair Fm2+/Fm3+". Inorg. Nucl. Chem. Lett. 13 (12): 651–656. doi:10.1016/0020-1650(77)80074-3.  ^ Nugent, L. J. (1975). MTP Int. Rev. Sci.: Inorg. Chem., Ser. One 7: 195–219.  ^ Samhoun, K.; David, F.; Hahn, R. L.; O'Kelley, G. D.; Tarrant, J. R.; Hobart, D. E. (1979). "Electrochemical study of mendelevium in aqueous solution: No evidence for monovalent ions". J. Inorg. Nucl. Chem. 41 (12): 1749–1754. doi:10.1016/0022-1902(79)80117-7.  ^ Koch, Lothar (2000). Transuranium Elements, in Ullmann's Encyclopedia of Industrial Chemistry. Wiley. doi:10.1002/14356007.a27_167.  Literature Robert J. Silva: Fermium, Mendelevium, Nobelium, and Lawrencium, in: Lester R. Morss, Norman M. Edelstein, Jean Fuger (Hrsg.): The Chemistry of the Actinide and Transactinide Elements, Springer, Dordrecht 2006; ISBN 1-4020-3555-1, p. 1621–1651; doi:10.1007/1-4020-3598-5_13. Seaborg, G.T. (ed.) (1978) Proceedings of the Symposium Commemorating the 25th Anniversary of Elements 99 and 100, 23 January 1978, Report LBL-7701 Gmelins Handbuch der anorganischen Chemie, System Nr. 71, Transurane: Teil A 1 II, p. 19–20; Teil A 2, p. 47; Teil B 1, p. 84. Wikimedia Foundation. 2010. Игры ⚽ Нужна курсовая? Francium Frédéric Chopin Look at other dictionaries: Fermium — Einsteinium ← Fermium → Mendélévium Er …   Wikipédia en Français fermium — [ fɛrmjɔm ] n. m. • 1957; de Fermi, n. pr. (→ fermion) ♦ Chim., phys. Élément artificiel radioactif (Fm; no at. 100; m. at. [des isotopes] 248 à 256), huitième élément transuranien découvert dans la série des actinides. ● fermium nom masculin (de …   Encyclopédie Universelle fermium — n. the transuranic element of atomic number 100; symbol Fm. The atomic weight of the most stable isotope, having a half life of about 80 days, is 257. The first isotope, Fm255 was discovered in 1952 in the debris of a thermonuclear explosion.… …   The Collaborative International Dictionary of English fermium — Symbol: Fm Atomic number: 100 Atomic weight: (253) Radioactive metallic transuranic element, belongs to the actinoids. Ten known isotopes, most stable is Fm 257 with a half life of 10 days. First identified by Albert Ghiorso and associates in the …   Elements of periodic system Fermium — discovered in the debris of a 1952 U.S. nuclear test in the Pacific, named 1955 for Italian born U.S. physicist Enrico Fermi (1901 1954) …   Etymology dictionary fermium — ☆ fermium [fer′mē əm, fʉr′mē əm ] n. [ModL: so named (1955) by A. Ghiorso and co workers, after FERMI Enrico (in honor of his studies in nuclear physics) + IUM] a radioactive, metallic chemical element, one of the actinides, produced by intense… …   English World dictionary Fermium — Eigenschaften …   Deutsch Wikipedia fermium — /ferr mee euhm/, n. Chem., Physics. a transuranic element. Symbol: Fm; at. no.: 100. [1950 55; named after E. FERMI; see IUM] * * * ▪ chemical element  (Fm), synthetic chemical element of the actinoid series of the periodic table, atomic number… …   Universalium Fermium — fermis statusas T sritis fizika atitikmenys: angl. fermium vok. Fermium, n rus. фермий, m pranc. fermium, m …   Fizikos terminų žodynas fermium — fermis statusas T sritis fizika atitikmenys: angl. fermium vok. Fermium, n rus. фермий, m pranc. fermium, m …   Fizikos terminų žodynas 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. 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