DUBNIUM

introduction

Numéro atomique: 105
Groupe: 5 or V B
Poids atomique: 262
Période: 7
Numero CAS: 53850-35-4

Classification

chalcogènes
Halogène
Gaz rare
lanthanides
actinides
Rare Earth Element
Groupe Platine Métal
Transuranium
Pas d'isotopes stables
Solide
Liquide
Gaz
Solide (prédit)

La description • Usages / Fonction

In 1967 G. N. Flerov reported that a Soviet team working at the Joint Institute for Nuclear Research at Dubna may have produced a few atoms of 260105 and 261105 by bombarding 243Am with 22Ne. Their evidence was based on time-coincidence measurements of alpha energies. More recently, it was reported that early in 1970 Dubna scientists synthesized Element 105 and that by the end of April 1970 “had investigated all the types of decay of the new element and had determined its chemical properties.” The Soviet group proposed the name joliotium for Element 105. In late April 1970, it was announced that Ghiorso, Nurmia, Harris, K. A. Y. Eskola, and P. L. Eskola, working at the University of California at Berkeley, had positively identified Element 105. The discovery was made by bombarding a target of 249Cf with a beam of 84 MeV nitrogen nuclei in the Heavy Ion Linear Accelerator (HILAC). When a 15N nuclear is absorbed by a 249Cf nucleus, four neutrons are emitted and a new atom of 260105 with a halflife of 1.6 s is formed. While the first atoms of Element 105 are said to have been detected conclusively on March 5, 1970, there is evidence that Element 105 had been formed in Berkeley experiments a year earlier by the method described. Ghiorso and his associates have attempted to confirm Soviet findings by more sophisticated methods without success. In October 1971, it was announced that two new isotopes of Element 105 were synthesized with the heavy ion linear accelerator by A. Ghiorso and co-workers at Berkeley. Element 261105 was produced both by bombarding 250Cf with 15N and by bombarding 249Bk with 16O. The isotope emits 8.93-MeV alpha particles and decays to 257Lr with a half-life of about 1.8 s. Element 262105 was produced by bombarding 249Bk with 18O. It emits 8.45 MeV alpha particles and decays to 258Lr with a half-life of about 40 s. Eight isotopes of Element 105 are now recognized. In 1997, the International Union of Pure and Applied Chemistry adopted the name dubnium for Element 105. 1

Propriétés physiques

Densité:   g/cm3

* - at 1 atm

Configuration de l'électron

Configuration de l'électron: [Rn] 7s2 5f14 6d3
Bloque: d
Plus haut niveau d'énergie occupés: 7
Électrons de valence: 

Nombres quantiques:

n = 6
ℓ = 2
m = 0
ms = +½

Bonding

isotopes

Nuclide Masse 2 Demi vie 2 Spin nucléaire 2 Énergie de liaison
255Db 255.10740(45)# 1.7(5) s [1.6(+6-4) s] 1,882.89 MeV
256Db 256.10813(31)# 1.9(4) s [1.6(+5-3) s] 1,890.96 MeV
257Db 257.10772(24)# 1.53(17) s [1.50(+19-15) s] (9/2+) 1,899.03 MeV
258Db 258.10923(37)# 4.5(6) s 1,907.10 MeV
259Db 259.10961(23)# 0.51(16) s 1,915.17 MeV
260Db 260.11130(25)# 1.52(13) s 1,913.93 MeV
261Db 261.11206(25)# 1.8(4) s 1,922.00 MeV
262Db 262.11408(20)# 35(5) s 1,930.07 MeV
263Db 263.11499(18)# 29(9) s [27(+10-7) s] 1,938.14 MeV
264Db 264.11740(25)# 3# min 1,946.21 MeV
265Db 265.1186(3)# 15# min 1,954.29 MeV
266Db 266.12103(39)# 20# min 1,953.04 MeV
267Db 267.12238(50)# 73(+350-33) min 1,961.11 MeV
268Db 268.12545(57)# 32(+11-7) h 1,969.18 MeV
269Db 269.12746(83)# 3# h 1,977.26 MeV
270Db 270.13071(77)# 1# h 1,976.01 MeV
Les valeurs marquées # ne sont pas purement dérivées des données expérimentales, mais au moins en partie des tendances systématiques. Spins avec de faibles arguments d'affectation sont entre parenthèses. 2

Abondance

Information de sécurité


Fiche signalétique - ACI Alloys, Inc.

Pour plus d'informations

Liens externes:

Sources

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:10.
(2) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(5) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).