Dubnium

TRANSITION METAL · GROUP 5 · PERIOD 7
105
Db
Dubnium
268

Atomic Data

Atomic Number105
SymbolDb
Atomic Weight268 u
Density (STP)N/A
Melting PointN/A °C (None K)
Boiling PointN/A °C (None K)
Electronegativity:
Electron Config.1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 5f14 6s2 6p6 6d3 7s2
Oxidation States+5
Phase at STPSolid
CategoryTransition Metal
Period / Group7 / 5
CAS Number53850-35-4

Electron Configuration

[Rn] 5f14 6d3 7s2

Shell n Subshell Electrons Cumulative
K11s22
L22s24
L22p610
M33s212
M33p618
M33d1028
N44s230
N44p636
N44d1046
N44f1460
O55s262
O55p668
O55d1078
O55f1492
P66s294
P66p6100
P66d3103
Q77s2105
Total 105 105

Isotopes of Dubnium

Dubnium is monoisotopic: ²⁶⁸Db is its only naturally occurring stable isotope, accounting for 100% of all natural Dubnium.

Isotope Symbol Protons Neutrons Abundance Stability
Dubnium-268²⁶⁸Db105163traceStable

Abundance & Occurrence

Dubnium is present in Earth's crust at approximately trace amounts by mass and at approximately trace amounts by mass throughout the universe.

Earth's Crust (ppm by mass)

Dubnium
None ppm
Silicon (ref.)
277,000 ppm
Oxygen (ref.)
461,000 ppm

Universe (ppm by mass)

Dubnium
None ppm
Helium (ref.)
230,000 ppm
Hydrogen (ref.)
739,000 ppm

Discovery & History

1968
Georgy Flerov et al. (Dubna): Dubna scientists reported synthesis of element 105 by bombarding americium with neon ions and proposed the name nielsbohrium: but replication difficulties again triggered a lengthy priority dispute with Berkeley.
1970
Albert Ghiorso et al. (Lawrence Berkeley): Ghiorso's team unambiguously produced element 105 by bombarding californium with nitrogen ions; they proposed the name hahnium after Otto Hahn, while the Dubna team's claim was also partially upheld.
1997
IUPAC: IUPAC settled the naming dispute by assigning dubnium (Db) to element 105, honouring the Dubna laboratory's contributions: the only element explicitly named after a Soviet/Russian research institution.

Read more about the discovery of the periodic table of elements →

Safety & Handling

  • Alpha radiation: Dubnium isotopes are alpha emitters with half-lives of seconds to hours (Db-268, t½ = 29 h is among the longest); production is limited to a few hundred atoms per experiment.
  • No bulk hazard: No macroscopic quantity of dubnium has ever existed; practical safety concerns relate to the accelerator and target activation, not the element itself.
  • Accelerator facility hazards: High-current heavy ion beams activate beam-line components producing short-lived radionuclides; hands-on maintenance of activated components requires careful dose assessment and cooling periods.
  • Regulatory controls: Transactinide synthesis is conducted under national and, where applicable, international nuclear regulatory licences.

Real-World Uses

  • Superheavy element chemistry: Dubnium (Db-262, Db-268) chemistry experiments test whether Group 5 superheavy element behaviour mirrors niobium and tantalum, or is altered by relativistic contraction of the 6d electron orbitals and spin-orbit splitting.
  • Nuclear decay spectroscopy: Dubnium isotope production at accelerators and measurement of their alpha-decay energies and half-lives refine the nuclear shell model in the superheavy region and feed into models predicting the island of stability.
  • No commercial applications: Dubnium is produced in tens to hundreds of atoms per experiment; half-lives range from seconds to hours, and no practical application is possible or anticipated.

Downloadable Resources

Free periodic table reference sheets for classrooms, study sessions, and laboratory use.

Colour PDF Black & White PDF

Frequently Asked Questions

Has dubnium ever been used for anything?

No. Dubnium has no known practical uses. It is produced only a few atoms at a time in particle accelerators and exists only briefly: its most stable isotope (Db-268) has a half-life of about 29 hours. It is studied solely to understand the nuclear and chemical properties of superheavy elements.

How many atoms of dubnium have ever been made?

Dubnium is produced in extremely small quantities: typically a few atoms per experiment. The total number of dubnium atoms ever produced across all experiments worldwide is likely in the range of millions of atoms, but since each atom lives for hours at most, none have accumulated. All experiments are done at the single-atom level using specialised detection techniques.

Is dubnium radioactive?

Yes, all isotopes of dubnium are radioactive. The longest-lived is Db-268 with a half-life of about 29 hours. It decays primarily by alpha emission and spontaneous fission. All dubnium isotopes are too short-lived and produced in too few numbers to pose any radiation hazard outside a specialised nuclear research facility.

How did dubnium get its name?

Dubnium was named after Dubna, Russia, the location of the Joint Institute for Nuclear Research (JINR): one of the two laboratories (along with Berkeley) that contested the discovery of element 105. The Berkeley team proposed hahnium (after Otto Hahn), while the Dubna team proposed nielsbohrium. After lengthy deliberations, IUPAC awarded the name dubnium to element 105 and gave element 107 the name bohrium, acknowledging both institutions' contributions.