| 词汇 | astatine |
| 释义 | astatine noun[ U ] uk /ˈæs.tə.tiːn/ us /ˈæs.tə.tiːn/ (symbolAt) a chemical element that is radioactive and is the rarest natural element on the Earth's surface: 砹（地球表面最为稀少的一种放射性化学元素） The properties of astatine remain a mystery.砹的属性仍然不为人知。 The lowest element in this group is also a highly radioactive and rare element, astatine. Fluorine and astatine are halogens. What is the physical state of astatine at room temperature? Chemical elements actinium alkali metal americium antimony berkelium bismuth brimstone calcium fluorine germanium lithium manganese nickel plutonium quicksilver selenium silicon sodium sulphur transition metal Examples of astatineastatine She discovered that the element 85 astatine is a product of the natural decay processes. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Accordingly, much less is known about astatine than most other elements. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Four out of these isotopes (astatine-215, astatine-217, astatine-218, and astatine-219) are found due to their production in major natural decay chains. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. The least stable ground state isotope is astatine-213, with a half-life of 125 nanoseconds. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Even though heavier astatine isotopes release less energy, no long-lived astatine isotope exists, due to the increasing role of beta decay (electron emission). From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. All of its isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. There are 32 known isotopes of astatine, with atomic masses (mass numbers) of 191 and 193223. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Astatine, which is usually classified as a nonmetal or a metalloid, has been predicted to have a metallic crystalline structure. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Francium is a highly radioactive metal that decays into astatine, radium, and radon. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. While hydroiodic acid solutions are stable, the hydronium-astatide solution is clearly less stable than the water-hydrogen-astatine system. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Astatine may be dark, or it may have a metallic appearance and be a semiconductor, or it may even be a metal. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. The properties he reported for dakin do not correspond to those of astatine, and the true identity of dakin is not known. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. A visible piece of astatine would be immediately and completely vaporized due to the heat generated by its intense radioactivity. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. The least stable one is astatine-214m1; its half-life of 265 nanoseconds is shorter than those of all ground states except that of astatine-213. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Astatine-219 decays to polonium-215, which itself beta decays to astatine-215 with an even smaller probability of 0.00023%. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. See all examples of astatine 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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