| 词汇 | berkelium |
| 释义 | berkelium noun[ U ] uk /bɜːˈkiː.li.əm/ us /ˈbɜ˞ː.kli.əm/ (symbolBk) a chemical element that is a soft, silver-white metal, and is radioactive: （放射性元素）锫 Berkelium is a very expensive and rare element.锫是一种非常昂贵的稀有元素。 He realized that berkelium could be extracted at the same time. The element was manufactured in a particle accelerator by smashing together isotopes of calcium and a radioactive element called berkelium. Chemical elements actinium alkali metal americium antimony astatine bismuth brimstone calcium fluorine germanium lithium manganese nickel plutonium quicksilver selenium silicon sodium sulphur transition metal Examples of berkeliumberkelium The production resulted in 22 milligrams of berkelium, enough to perform the experiment. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. The isotope which is the easiest to synthesize is berkelium-249. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. The production of the second-important isotope berkelium-247 involves the irradiation of the rare isotope curium-244 with high-energy alpha particles. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. In a thermal reactor, much of it will therefore be converted to berkelium-250 which quickly decays to californium-250. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. The coordination of the berkelium atom in its trivalent fluoride and chloride is tricapped trigonal prismatic, with a coordination number of 9. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. He was part of the team that discovered elements 97 and 98 (berkelium and californium) in 1949 and 1950. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Since ununseptium has 117 protons in its nucleus and calcium has 20, they thus needed to use berkelium, which has 97 protons in its nucleus. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Berkelium is a soft, silvery-white, radioactive metal. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Specifically, berkelium-249 has a moderately large neutron capture cross section of 710 barns for thermal neutrons, 1200 barns resonance integral, but very low fission cross section for thermal neutrons. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. The most difficult steps in the synthesis of berkelium were its separation from the final products and the production of sufficient quantities of americium for the target material. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. All of the elements with higher atomic numbers, however, have been first discovered in the laboratory, with neptunium, plutonium, americium, curium, berkelium and californium later also discovered in nature. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Other elements are named after modern states or cities, with berkelium and californium being named after the city and the state where these elements were discovered. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. The radioactive decay of uranium produces transient amounts of actinium and protactinium, and atoms of neptunium, americium, curium, berkelium and californium are occasionally produced from transmutation reactions in uranium ores. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. 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 19491950. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. The remaining 7 transient elements (technetium, promethium, neptunium, americium, curium, berkelium, and californium) occur only rarely, as products of rare nuclear reaction processes involving uranium or other heavy elements. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. See all examples of berkelium These examples are from corpora and from sources on the web. Any opinions in the examples do not represent the opinion of the Cambridge Dictionary editors or of Cambridge University Press or its licensors. |
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