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Hf

Ta

W

Rf

Db

Sg

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Element Fact
Iridium is the most corrosion-resistant metal known. Together with platinum, it is used to make the international prototype of the kilogram, which is the standard definition for the unit of mass.

Dubnium, Db

dubnium sample

Atomic number: 105
Atomic mass: [262] (no stable nuclide)
Natural abundance: -
Isotopes: -

History and Production

Named after the Joint Institute for Nuclear Research in Dubna, Russia. Discovered in Dubna by G.N. Flerov and others in 1967, after americium was bombarded with neon ions. In their experiments 260Db and 261Db may have produced. In a seperate incident, A. Ghiorso and co-workers at Berkeley in 1970 claimed to have positively identified the Element 105, by bombarding a target of 249Cf with 15N nuclei in the Heavy Ion Linear Accelerator. 260Db with a half-life of 1.6 seconds was reported to have formed. In 1971, the same groups at Berkeley claimed to have synthesized two new isotopes, 261Db and 262Db. Initially, the name for the new element has been suggested as hahnium and joliotium, named after O. Hahn and J.-F. Joliot and Mme. Joliot-Curie. However, the naming issue was resolved by IUPAC in 1997 and Element 105 was given the name dubnium.

Physical Data

Only few atoms have ben produced which quickly dissappear by spontaneous fission. The properties of the element therefore is not known.

Interatomic distance: -
Melting point: n/a
Boiling point: n/a
Thermal conductivity/Wm-1K-1: n/a
Density/kgm-3: 39000 (est.)

Standard Thermodynamic Data (atomic gas)

Enthalpy of formation: -
Gibbs free energy of formation: -
Entropy: -
Heat capacity: -

Electronic data

Electronic configuration: Electronic configuration: [Rn] 5f14 6d3 7s2
Term symbol: 4F3/2
Electron affinity: -   Electronegativity (Pauline): -
Ionization energy (first, second, third): 640 (est.), -, - kJ/mol

Chemical properties


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