protactiniumn.

Brit.

/ˌprəʊtakˈtɪnɪəm/, U.S.

/ˌproʊtækˈtɪniəm/

Forms:

α. 1900s– proactinium.

β. 1900s– protactinium, 1900s– protoactinium.

Origin: A borrowing from German. Etymon: German Protactinium.

Etymology: < German Protactinium (O. Hahn & L. Meitner 1918, in Physikalische Zeitschr. 19 211/1) < slightly earlier Proactinium ( < pro- pro- prefix² + Actinium actinium n.) with insertion of -t- for euphony; so named because the principal isotope is converted into actinium by radioactive decay.In the form proactinium directly < German Proactinium (see above). In the form protoactinium altered after proto- comb. form. Compare:1970 Biogr. Mem. Fellows Royal Soc. 16 407 By the end of the war the discovery of protactinium (not protoactinium; the t had been inserted to avoid just such a clash of vowels in proactinium, the name first considered) was ready to be published. The form protactinium is that adopted by the International Union of Pure and Applied Chemistry in 1949.

Chemistry.

A rare, radioactive, metallic chemical element, atomic number 91, which is a member of the actinide series and occurs in small quantities as a decay product in uranium ores. Symbol Pa.The longest-lived isotope (protactinium-231) has a half-life of about 32,500 years.

ΘΚΠ

the world > matter > chemistry > elements and compounds > metals > specific elements > protactinium > [noun]

protactinium1918

1918 Jrnl. Chem. Soc. 114 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.

1919 Chem. Abstr. 13 1181 Protactinium is one of the 5 new radioactive elements occupying a place in the periodic table hitherto vacant.

1934 Nature 8 Sept. 386/1 The protoactinium was precipitated with zirconium as phosphate in the earlier stages.

1959 New 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.

1970 J. W. Gardner Atoms Today & Tomorrow vi. 99 The decay chain proceeds from thorium (atomic number 90) via protactinium (atomic number 91) to uranium.

1987 Inorg. Chem. 26 1410 A proactinium complex whose sandwich structure was later demonstrated.

1997 Nature 3 July 21/2 The heaviest-known group-5 element hahnium behaves more like the actinide protactinium and the lighter group-5 element niobium than its closest homologue tantalum.

This entry has been updated (OED Third Edition, June 2007; most recently modified version published online March 2022).

单词	protactinium
释义	protactiniumn. Brit. /ˌprəʊtakˈtɪnɪəm/, U.S. /ˌproʊtækˈtɪniəm/ Forms: α. 1900s– proactinium. β. 1900s– protactinium, 1900s– protoactinium. Origin: A borrowing from German. Etymon: German Protactinium. Etymology: < German Protactinium (O. Hahn & L. Meitner 1918, in Physikalische Zeitschr. 19 211/1) < slightly earlier Proactinium ( < pro- pro- prefix² + Actinium actinium n.) with insertion of -t- for euphony; so named because the principal isotope is converted into actinium by radioactive decay.In the form proactinium directly < German Proactinium (see above). In the form protoactinium altered after proto- comb. form. Compare:1970 Biogr. Mem. Fellows Royal Soc. 16 407 By the end of the war the discovery of protactinium (not protoactinium; the t had been inserted to avoid just such a clash of vowels in proactinium, the name first considered) was ready to be published. The form protactinium is that adopted by the International Union of Pure and Applied Chemistry in 1949. Chemistry. A rare, radioactive, metallic chemical element, atomic number 91, which is a member of the actinide series and occurs in small quantities as a decay product in uranium ores. Symbol Pa.The longest-lived isotope (protactinium-231) has a half-life of about 32,500 years. ΘΚΠ the world > matter > chemistry > elements and compounds > metals > specific elements > protactinium > [noun] protactinium1918 1918 Jrnl. Chem. Soc. 114 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. 1919 Chem. Abstr. 13 1181 Protactinium is one of the 5 new radioactive elements occupying a place in the periodic table hitherto vacant. 1934 Nature 8 Sept. 386/1 The protoactinium was precipitated with zirconium as phosphate in the earlier stages. 1959 New 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. 1970 J. W. Gardner Atoms Today & Tomorrow vi. 99 The decay chain proceeds from thorium (atomic number 90) via protactinium (atomic number 91) to uranium. 1987 Inorg. Chem. 26 1410 A proactinium complex whose sandwich structure was later demonstrated. 1997 Nature 3 July 21/2 The heaviest-known group-5 element hahnium behaves more like the actinide protactinium and the lighter group-5 element niobium than its closest homologue tantalum. This entry has been updated (OED Third Edition, June 2007; most recently modified version published online March 2022). < n.1918
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