一二三四区视频,亚洲少妇熟女色,日本久热无码视频网,欧美国产日韩大尺度,亚洲a视频,久久少妇一区二区,日韩999无码视频,刺激久久久久久久,啊啊啊啊不要啊在线

fermium

fermium Struktur
CAS-Nr.
Englisch Name:
fermium
Synonyma:
CBNumber:
CB4945925
Summenformel:
Fm
Molgewicht:
257
MOL-Datei:
Mol file

fermium Eigenschaften

Sicherheit

fermium Chemische Eigenschaften,Einsatz,Produktion Methoden

Physikalische Eigenschaften

Fermium is the eighth transuranic element in the actinide series of group 14 (IVA) of theperiodic table. Similar to einsteinium, fermium was produced and discovered in the debrisresulting from the explosion of the nuclear hydrogen bomb in 1952. Its existence was keptsecret because of security measures that were established during World War II, thus keepingAlbert Ghiorso and his colleagues at the University of California at Berkeley from receivingcredit for the discovery until 1955. Fermium’s melting point is thought to be about1500+degrees Celsius, but its boiling point and density are unknown since so little of it isproduced and because of the short half-lives of its isotopes.

Isotopes

There are a total of 21 isotopes of fermium. Their half-lives range from fermium-258’s 370 microseconds to fermium-257’s 100.5 days, which is the longest of allits isotopes. None of fermium’s isotopes exist in nature. All are artificially produced andare radioactive.

Origin of Name

Named after and to honor the scientist Enrico Fermi.

Occurrence

Fermium does not exist in nature. All of it is artificially produced in cyclotrons, isotopeparticle accelerators, or nuclear reactors by a very complicated decay process involving six stepsof nuclear bombardment followed by the decay of beta particles, as follows:1. Plutonium-239 (plus 2 neutrons) to 94Pu-241 → americium-241+ β-.2. Americium-241 (plus 1 neutron) to 95Am-242 → to curium-242 + β-.3. Curium-242 (plus 7 neutrons) to 96Cm-249 → to berkelium-249 + β-.4. Berkelium-249 (plus 7 neutrons) to 97Bk-250 → to californium-250 + β-.5. Califorium-250 (plus 3 neutrons) to 98Ca-253 → to einsteinium-253 + β-.6. Einstenium-253 (plus 1 neutron) to 99Es-254 → to fermium-254 + β-.

History

Fermium, the eighth transuranium element of the actinide series to be discovered, was identified by Ghiorso and co-workers in 1952 in the debris from a thermonuclear explosion in the Pacific in work involving the University of California Radiation Laboratory, the Argonne National Laboratory, and the Los Alamos Scientific Laboratory. The isotope produced was the 20-hour 255Fm. During 1953 and early 1954, while discovery of elements 99 and 100 was withheld from publication for security reasons, a group from the Nobel Institute of Physics in Stockholm bombarded 238U with 16O ions, and isolated a 30-min α-emitter, which they ascribed to 250100, without claiming discovery of the element. This isotope has since been identified positively, and the 30-min half-life confirmed. The chemical properties of fermium have been studied solely with tracer amounts, and in normal aqueous media only the (III) oxidation state appears to exist. The isotope 254Fm and heavier isotopes can be produced by intense neutron irradiation of lower elements such as plutonium by a process of successive neutron capture interspersed with beta decays until these mass numbers and atomic numbers are reached. Twenty isotopes and isomers of fermium are known to exist. 257Fm, with a half-life of about 100.5 days, is the longest lived. 250Fm, with a half-life of 30 min, has been shown to be a product of decay of Element 254102. It was by chemical identification of 250Fm that production of Element 102 (nobelium) was confirmed. Fermium would probably have chemical properties resembling erbium.

Charakteristisch

The chemical characteristics of fermium are not very well known, but they are similarto its homologue erbium, the rare-earth element located just above it in the lanthanideseries.
The nuclear reaction in the hydrogen bomb that produced fermium was the result of theacquisition of 17 neutrons by uranium from the explosion resulting in uranium-255 and somegamma radiation. U-255 decays by β-electron emission to form fermium-255, as depicted inthe equation as follows: 92U-238 + 17 neutrons and gamma radiation → 92U-255 → 100Fm-255 + the emission of 8 electrons.

Verwenden

Because such small amounts of fermium are produced and because the half-lives of its isotopesare so short, there are no commercial uses for it except for basic scientific research.

Definition

Element 100, aw 254, valence of 3, half-life 3 h. A synthetic radioactive element with atomic number 100 discovered in 1952. Fermium has since been prepared in a nuclear reactor by irradiating californium, plutonium, or einsteinium with neutrons in a cycl

Hazard

All the radioisotopes of fermium are dangerous radiation hazards. There is little chance ofcoming in contact with one of fermium’s isotopes given that they all have very short half-livesand do not exist for long periods. In addition, very small amounts are produced and mainlyavailable for research purposes.

fermium Upstream-Materialien And Downstream Produkte

Upstream-Materialien

Downstream Produkte


fermium Anbieter Lieferant Produzent Hersteller Vertrieb H?ndler.

Global( 0)Lieferanten
Firmenname Telefon E-Mail Land Produktkatalog Edge Rate
Copyright 2019 ? ChemicalBook. All rights reserved
昭平县| 浙江省| 伊川县| 金川县| 旺苍县| 隆尧县| 蒙自县| 郎溪县| 连城县| 肇源县| 略阳县| 长汀县| 山丹县| 揭阳市| 游戏| 阿尔山市| 乌兰县| 芦溪县| 茂名市| 工布江达县| 长垣县| 苍梧县| 皋兰县| 东至县| 威宁| 大宁县| 龙南县| 邯郸市| 屯留县| 卢龙县| 鹤山市| 渑池县| 肥西县| 灌云县| 普兰店市| 蒙自县| 白山市| 烟台市| 文昌市| 玛多县| 洛南县|