| 释义 |
protactinium Chem.|prəʊtækˈtɪnɪəm|
Also protoactinium |ˌprəʊtəʊækˈtɪnɪəm|.
[mod.L., coined (as protactinium) in Ger. (Hahn & Meitner 1918, in Physik. Zeitschr. XIX. 211/1) see proto- and actinium 2. So named because the principal isotope produces actinium by radioactive decay.]
A radioactive metallic element of the actinide series, which occurs in small quantities as a decay product in uranium ores, and whose longest-lived isotope has a half-life of about 33,000 years. Atomic number 91; symbol Pa.
The spelling protactinium is that adopted by the International Union of Pure and Applied Chemistry.
1918Jrnl. Chem. Soc. CXIV. ii. 346 Assuming that 8% of the uranium atoms disintegrating produce ‘protoactinium’, the quantity in the 73 mg. is that in equilibrium with 86 grams of uranium. 1919Chem. Abstr. XIII. 1181 Protactinium is one of the 5 new radioactive elements occupying a place in the periodic table hitherto vacant. 1934Nature 8 Sept. 386/1 The protoactinium was precipitated with zirconium as phosphate in the earlier stages, partly freed from zirconium by fractional crystallization and precipitated together with tantalum. 1934Times 13 Sept. 9/4 The successful isolation of protactinium, the parent element in the actinium series of radioactive changes, was announced yesterday. 1959New Scientist 17 Dec. 1264/3 From 60 tons of waste material from the production of uranium from its ores, chemists at Windscale have with some difficulty extracted 100 grammes of protactinium. 1962Cotton & Wilkinson Adv. Inorg. Chem. xxxii. 906 Protactinium as 231Pa..occurs in pitchblende, but even the richest ores contain only about 1 part Pa in 107. The isolation of protactinium..is difficult, as indeed is the study of protactinium chemistry generally, owing to the extreme tendency of the compounds to hydrolyze. 1970J. W. Gardner Atoms Today & Tomorrow vi. 99 The decay chain proceeds from thorium (atomic number 90) via protactinium (atomic number 91) to uranium. 1973Phillips & Milner in J. C. Bailar et al. Comprehensive Inorg. Chem. V. 79 Protactinium is the third member of the actinide series, but it possesses many of the properties of the Group V elements in its chemical reactions... The stable valency state in solution is Pa(V), and the existence of Pa(IV) is also possible. |