105
  Db  
262.000000
Dubnium

Name: Dubnium
Symbol: Db
Atomic Number: 105
AtomicWeight: 262.000000
Family: transition metals
CAS RN: 53850-35-4
Description: A synthetic element not present in nature, appearance unknown, probably metallic solid.
State (25 C): Unknown (Synthetic)
Oxidation states:
Valence Electrons: 6d37s2

Boiling Point:  unknown
Melting Point:
unknown
Electrons Energy Level: 2, 8, 18, 32, 32, 11, 2
Isotopes: 16 + None Stable
Heat of Vaporization: unknown
Heat of Fusion: unknown
Density: unknown
Specific Heat: unknown
Atomic Radius: unknown
Ionic Radius: unknown
Electronegativity: unknown
Vapor Pressure: unknown
1s2 2s2p6 3s2p6d10 4s2p6d10f14 5s2p6d10f14 6s2p6d3 7s2

History

Dubnium (named after Dubna, Russia) was reportedly first synthesized by G. N. Flerov in 1967 at the Joint Institute for Nuclear Research in Dubna, Russia (reportedly producing nuclide 260105 and nuclide 261105 by bombarding 243Am with 22Ne).  Their evidence was based on time-coincidence measurements of alpha energies.  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 Albert Ghiorso, Nurmia, Haris, 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) a particle accelerator.  When a 15N nuclear is absorbed by a 249Cf nucleus, four neutrons are emitted and a new atom of 260105 with a half-life 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.

The Berkeley scientists later tried to confirm the Soviet findings using more sophisticated methods but were not successful. They proposed that the new element should be named hahnium (symbol Ha) in honor of the late German scientist Otto Hahn (1879 - 1968).   Consequently this was the name that most American and Western European scientists used.

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 seconds.   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 seconds.  Fifteen isotopes of Element 105 are now recognized.  In 1994 the International Union of Pure and Applied Chemistry recommended the name joliotium for Element 105; however, the matter was not settled.

An element naming controversy erupted over what to name this element after Russian researchers protested. The International Union of Pure and Applied Chemistry (IUPAC) thus adopted unnilpentium, symbol Unp, as a temporary, systematic element name.   However, in 1997 they resolved the dispute and adopted the current name, dubnium (symbol Db), after the city that contains the Russian Joint Institute for Nuclear Research.  Its former names have included hahnium, joliotium and nielsbohrium.

1s2
2s2 2p6
3s2 3p6 3d10
4s2 4p6 4d10 4f14
5s2 5p6 5d10 5f14
6s2 6p6 6d3
7s2

Isotopes

Dubnium , also called eka-tantalum is a highly radioactive synthetic element whose most stable isotope has a half-life of 32 hours, 268Db.  This relatively high stability compared to the surrounding elements on the periodic table gives evidence that by manipulating the number of neutrons in a nucleus, one can alter the stabilities of such nuclei.

atom.gif (700 bytes)

Isotopes  
Atomic Mass
 
Half-Life
255Db 255.10740 1.7 seconds
256Db 256.10813 1.9 seconds
257Db 257.10772 1.53 seconds
258Db 258.10923 4.5 seconds
259Db 259.10961 0.51 seconds
260Db 260.11130 1.52 seconds
261Db 261.11206 1.8 seconds
262Db 262.11408 35 seconds
263Db 263.11499 29 seconds
264Db 264.11740 ~3 minutes
265Db 265.1186 ~15 minutes
266Db 266.12103 ~20 minutes
267Db 267.12238 73 minutes
268Db 268.12545 32 hours
269Db 269.12746 ~3 hours
270Db 270.13071 ~1 hours

atom.gif (700 bytes)

Dubnium Data
 

Atomic Structure

  • Atomic Radius:
  • Atomic Volume:
  • Covalent Radius:
  • Cross Section (Thermal Neutron Capture) Barns: 
  • Crystal Structure:
  • Electron Configuration:
    1s2 2s2p6 3s2p6d10 4s2p6d10f14 5s2p6d10f14 6s2p6d3 7s2
  • Electrons per Energy Level: 2, 8, 18, 32, 32, 11, 2
  • Ionic Radius:
  • Filling Orbital:
  • Number of Electrons (with no charge): 105
  • Number of Neutrons (most common/stable nuclide): 157
  • Number of Protons: 105
  • Oxidation States:
  • Valence Electrons:

Chemical Properties

  • Electrochemical Equivalent:
  • Electron Work Function:
  • Electronegativity: N/A (Pauling); N/A (Allrod Rochow)
  • Heat of Fusion: kJ/mol
  • Incompatibilities:
  • Ionization Potential
    • First:
  • Valence Electron Potential (-eV):

Physical Properties

  • Atomic Mass Average: 262
  • Boiling Point:
  • Coefficient of Lineal Thermal Expansion/K-1: N/A
  • Conductivity
    Electrical:
    Thermal: 0.58 W/cmK
  • Description:
    Man made radioactive element.
  • Flammablity Class:
  • Freezing Point: see melting point
  • Heat of Vaporization:kJ/mol
  • Melting Point:
  • Physical State (at 20C & 1atm):
  • Specific Heat:

Regulatory / Health

  • CAS Number
    • 53850-35-4
  • NFPA 704
    • Health:
    • Fire:
    • Reactivity:
    • Special Hazard: Radioactive
    • OSHA Permissible Exposure Limit (PEL)
      • No limits set by OSHA
    • OSHA PEL Vacated 1989
      • No limits set by OSHA
    • NIOSH Recommended Exposure Limit (REL)
      • No limits set by NIOSH
    • Levels In Humans:
      Note: this data represents naturally occuring levels of elements in the typical human, it DOES NOT represent recommended daily allowances.
      • Blood/mg dm-3: nil
      • Bone/p.p.m: nil
      • Liver/p.p.m: nil
      • Muscle/p.p.m: nil
      • Daily Dietary Intake: nil
      • Total Mass In Avg. 70kg human: nil

    Who / Where / When / How

    • Discoverer: the Joint Institute for Nuclear Research/University of Califorinia
    • Discovery Location: Dubna Russia (USSR)/Berkeley Califorinia
    • Discovery Year: 1970
    • Name Origin:
      After the city of Dubna Russia home to the Joint Institute for Nuclear Research
    • Abundance:
      • Earth's Crust/p.p.m.: nil
      • Seawater/p.p.m.: nil
      • Atmosphere/p.p.m.: nil
      • Sun (Relative to H=1E12): N/A
    • Sources:
      First synthisized by bombarding Am243 with Ne22. Only a small number of atoms of dubnium have ever been produced.
    • Uses:
      None
    • Additional Notes:
      In August of 1997 the International Union of Pure and Applied Chemistry announced the official naming of this element as Dubnium. Db-260 and Db-261 were tentatively reported in 1967 by scientists in Dubna Russia. It was not until 1970 that Db-260 had been confirmed by scientists in Dubna Russia and Berkeley Califorinia USA independantly. In 1992 the IUPAC concluded that credit for this discovery should be shared between the two groups of scientists.

Transition Metals
Group 3
(IIIB)
4
(IVB)
5
(VB)
6
(VIB)
7
(VIIB)
8
(VIIIB)
9
(VIIIB)
10 (VIIIB) 11
(IB)
12
(IIB)
Period 4 21
Sc
44.95
22
Ti
47.86
23
V
50.94
24
Cr
51.99
25
Mn
54.93
26
Fe
55.84
27
Co
58.93
28
Ni
58.69
29
Cu
63.54
30
Zn
65.39
Period 5 39
Y
88.90
40
Zr
91.22
41
Nb
92.90
42
Mo
95.94
43
Tc
98.00
44
Ru
101.0
45
Rh
102.9
46
Pd
106.4
47
Ag
107.8
48
Cd
112.4
Period 6 57
La
138.9
72
Hf
178.4
73
Ta
180.9
74
W
183.8
75
Re
186.2
76
Os
190.2
77
Ir
192.2
78
Pt
195.0
79
Au
196.9
80
Hg
200.5
Period 7 89
Ac
227.0
104
Rf
261.0
105
Db
262.0
106
Sg
266.0
107
Bh
264.0
108
Hs
269.0
109
Mt
268.0
110
Ds
269.0
111
Uuu
272.0
112
Uub
277.0