Dubnium

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.

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.

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

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 20°C & 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

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