Curium protactinium

Each of the elements has a number of isotopes (2,4), all radioactive and some of which can be obtained in isotopicaHy pure form. More than 200 in number and mosdy synthetic in origin, they are produced by neutron or charged-particle induced transmutations (2,4). The known radioactive isotopes are distributed among the 15 elements approximately as follows actinium and thorium, 25 each protactinium, 20 uranium, neptunium, plutonium, americium, curium, californium, einsteinium, and fermium, 15 each herkelium, mendelevium, nobehum, and lawrencium, 10 each. There is frequently a need for values to be assigned for the atomic weights of the actinide elements. Any precise experimental work would require a value for the isotope or isotopic mixture being used, but where there is a purely formal demand for atomic weights, mass numbers that are chosen on the basis of half-life and availabiUty have customarily been used. A Hst of these is provided in Table 1. 

Actinium 22 Thorium Protactinium M.04 Uranium 23g.lL1 Neptunium ( -i Plutonium i244 Americium 211 Curium -247i Berkelium -24- Californium 25H Einsteinium 252 Fermium IS Meodeievium 1258 Nobelium 25G... 

Thorium Protactinium Uranium Neptunium Plutonium Ameridum Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrendum... 

This article presents a general discussion of actinide metallurgy, including advanced methods such as levitation melting and chemical vapor-phase reactions. A section on purification of actinide metals by a variety of techniques is included. Finally, an element-by-element discussion is given of the most satisfactory metallurgical preparation for each individual element actinium (included for completeness even though not an actinide element), thorium, protactinium, uranium, neptunium, plutonium, americium, curium, berkelium, californium, and einsteinium. 

Th Thorium 232.03S1 91 Pa Protactinium 92 U Uranium 93 Np Neptunium 94 Pu Plutonium 95 Am Americium 96 Cm Curium 97 Bk Berkelium 98 Cf Californium 99 ES Einsteinium 100 Fm Fermium 101 Md Vlendelevium 102 No Nobelium Lr Lawrencium... 

ACTINIUM THORIUM PROTACTINIUM URANIUM NEPTUNIUM PLUTONIUM AMERICIUM CURIUM BERKELIUM CALIFORNIUM EINSTEINIUM FERMIUM MENDELEVIUM NOBELIUM... 

Curium, aber nicht von Thorium und Protactinium bekannt. Nach der von Burns et al. am Beispiel der Zr-Verbindung durchgefuhrten Struktur-bestimmung des Typs Me Me "F31 wird diese Struktur am bestendurch die Schreibweise 6 NaZrFs NaF wiedergegeben 222>. 

Protactinium is silvery and relatively unreactive, but actinium and curium are so radioactive that they glpw. Neptunium is similar to uranium and plutonium in appearance. Americium is similar and is very electropositive, dissolving readily in acids to give the Am3+ ion. 

Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkellum Caiiiornlum Einsteinium Permium Mendelevlum Nobelium Lawrenaum ... 

Series on Rajdiochemistry, National Academy of Sciences. Reports available from Office of Technical Services, Department of Commerce, Washington, D C. P. C. Stevenson and W. E. Nervik, Actinium (with scandium, yttrium, rare earths), NAS-NS-3020 E. Hyde, Thorium, NAS-NS 3004 H. W. Kirby, Protactinium, NAS-NS-3016 ]. E. Gindler, Uranium, NAS-NS-3030 G. A. Burney and R M. Harbour, Neptunium, NAS-NS-3060 G. H. Coleman and R. W. Hoff, Plutonium, NAS-NS-3058 R. A. Peimeman and R. K Keenan, Americium and Curium,... 

Thorium Protactinium Uranium Nepturtium Plutonium Americium Curium Berkellum Californium Einsteinium Fermium Mendelevium Nobelium lawtenclum... 

Unit cell dimensions for the tetravalent protactinium fluoro complexes are listed in Table VIII. LiPaFs is a member of an isostructural series of 1 1 complexes formed by the actinide elements thorium to curium inclusive (91). Structural details are available for LiUP5 (5S), but bond distances have not been reported for the protactinium complex. The 7 6 complexes, like their actinide(IV) analogs (Th-Cm with Na, Th-Cm with K, and Th-Pu with Rb) are all 4, 114) isostructural with Na7Zr F3 (60) in which each zirconium atom is 8-coordinate and the... 

Ho Holmium Er Erbium Tm Thulium Yb Ytterbium Lu l.utetium f Hf Hafnium Ta Tantalum W Wolfram f Re Rhenium Os Osmium Ir Iridium Pt Platinum Au Gold Hg Mercury Tl Thallium Pb Lead Bi Bismuth Po Polonium At Astatine f Rn Radon Fr Francium f Ra Radium Ac Actinium Th Thorium Pa Protactinium U Uranium Np Neptunium f Pu Plutonium f Am Americium f Cm Curium f Bk Berkelium f Cf Californium i... 

The solution photochemistry of the actinides begins with uranium none has been reported for actinium, thorium, and protactinium. Spectra have been obtained for most of the actinide ions through curium in solution (5). Most studies in actinide photochemistry have been done on uranyl compounds, largely to elucidate the nature of the excited electronic states of the uranyl ion and the details of the mechanisms of its photochemical reactions (5a). Some studies have also been done on the photochemistry of neptunium (6) and plutonium (7). Although not all of these studies are directed specifically toward separations, the chemistry they describe may be applicable. 

In the transthorium elements (with Z above 90) there was around 1955 a controversy 16 17) whether some 6 d electrons might occur, rather than a partly filled 5 f shell in agreement with Eqs. (4) and (5). The situation seems quite complicated in alloys of protactinium, uranium and neptunium with other metals, whereas plutonium may choose between 5 f4 Pu[IV] and 5 fs Pu[III] in the individual alloys or modifications of the element. On the other hand, americium and curium seem al-... 

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