Hassium (Hs)
transition-metalSolid
Standard Atomic Weight
[270]Electron configuration
[Rn] 7s2 5f14 6d6Melting point
N/ABoiling point
N/ADensity
4.07e+4 kg/m³Oxidation states
+3, +4, +6, +8Electronegativity (Pauling)
N/AIonization energy (1st)
7.6 eVDiscovery year
1984Atomic radius
126 pmDetails
Hassium is a synthetic transactinide element in group 8, below osmium. It is known only from atom-at-a-time production in heavy-ion reactions, and all confirmed isotopes are radioactive and short-lived. Its chemistry is important mainly because it tests whether very heavy elements still follow periodic trends despite strong relativistic effects. Experiments show behavior consistent with a heavy osmium analogue, especially in the formation of a volatile tetroxide.
Hassium does not occur naturally in the Earth’s crust. Hassium was first synthesized by German scientists at the GSI Center for Heavy Ion Research in Darmstadt, Germany in 1984 using the nuclear reaction 208Pb (58Fe, n) 265Hs (Fig. IUPAC.108.1). The element is named for Hassia (the Latin name for the German state of Hesse), whose former capital was Darmstadt [651], [652], [653]. Hassium is used in chemical and heavy element research.
Hassium was first produced by Peter Armbruster, Gottfried Münzenber and their team working at the Gesellschaft für Schwerionenforschung in Darmstadt, Germany in 1984. They bombarded atoms of lead-208 with ions of iron-58 with a device known as a linear accelerator. This produced atoms of hassium-265, an isotope with a half-life of about 2 milliseconds (0.002 seconds), and a free neutron. Hassium's most stable isotope, hassium-270, has a half-life of about 22 seconds. It decays into seaborgium-266 through alpha decay.
Its name is Latin "Hassias" meaning "Hess," from the German state. Discovered by Peter Armbruster, Gottfried Munzenber and co-workers at GSI in Darmstadt, Germany in 1984.
No macroscopic sample of hassium has been prepared, so its visible appearance is unknown. Calculations predict a dense metallic solid under ordinary conditions, but color, crystal form, and most bulk physical properties have not been observed directly.
Hassium has no commercial, medical, or industrial use. Its use is confined to nuclear and chemical research, where individual atoms are made to study superheavy-element stability, decay chains, and relativistic effects on chemical behavior. Chemical experiments with hassium are also used to test group 8 periodicity at the end of the known periodic table. The element is not available in quantities suitable for materials testing or applied technology.
Since only small amounts of hassium have ever been produced, it currently has no uses outside of basic scientific research.
The best-established chemical species is hassium tetroxide (HsO₄), formed in atom-at-a-time gas-phase experiments under oxidizing conditions. Its behavior is broadly comparable to osmium tetroxide (OsO₄), supporting the placement of hassium in group 8 and the accessibility of the +8 oxidation state. Other oxidation states and compounds are mainly predicted from theory or inferred by analogy with ruthenium and osmium. No isolable bulk hassium compound has been characterized.
See more information at the Hassium compound page.
Hassium isotopes are intensely radioactive on an atom-by-atom basis, decaying mainly by alpha emission and spontaneous fission, depending on the isotope. Because only a few atoms are produced, ordinary chemical toxicity has no practical relevance. The real hazards in hassium work come from accelerator operations, radioactive targets and products, recoil collection systems, and contamination control in specialized laboratories.
Hassium has no confirmed natural occurrence and no known environmental cycle. Atoms produced in laboratories decay rapidly, so environmental transport, bioaccumulation, and ecological effects have not been observed. If released as individual atoms or simple compounds, its chemistry would probably resemble that of a very heavy group 8 element, but this remains experimentally limited and environmentally irrelevant at present production scales.
Hassium has no commodity market, no industrial demand, and no practical supply chain. It is produced only in specialized nuclear laboratories by bombarding heavy actinide or lead targets with accelerated ions, yielding at most small numbers of atoms. The limiting factors are accelerator access, target preparation, detection efficiency, and isotope half-life rather than raw material price. There is no recycling or stockpiling of hassium as a usable material, because produced atoms decay during the experiment.
Formed by the bombardment of lead-208 with iron-58.
Hassium is not expected to persist as a primordial element because its known isotopes have half-lives far too short on geological or cosmic timescales. Superheavy nuclei in this mass region may be formed transiently in extreme neutron-rich nucleosynthesis, but no extraterrestrial hassium has been detected. Any such atoms would decay into lighter nuclides unless an unknown long-lived isotope existed.
- Hassium was named after Hesse, the German state where it was first synthesized.
- Its chemical study has been performed with single atoms carried through apparatus before they decay.
- The volatile tetroxide was central to confirming its group 8 character.
- Known hassium isotopes are identified largely through their decay chains.
- No weighed sample of hassium has ever existed.
Images
Properties
Physical
- Atomic radius (empirical)
- 126 pm Compare Atomic radius (empirical) of all elements →
- Density
- 4.07 × 104 kg/m³ Compare Density of all elements →
Chemical
- Electron affinity
- 1.1 eV
- Ionization energy (1st)
- 7.6 eV Compare Ionization energy (1st) of all elements →
- Ionization energy (2nd)
- 18.200063 eV Compare Ionization energy (2nd) of all elements →
- Ionization energy (3rd)
- 29.300101 eV Compare Ionization energy (3rd) of all elements →
- Ionization energy (4th)
- 37.70013 eV Compare Ionization energy (4th) of all elements →
- Ionization energy (5th)
- 51.200176 eV Compare Ionization energy (5th) of all elements →
- Oxidation states
- +3, +4, +6, +8 Compare Oxidation states of all elements →
- Valence electrons
- 8 Compare Valence electrons of all elements →
- Electron configuration
- [Rn] 7s2 5f14 6d6
Thermodynamic
N/A
Nuclear
- Protons
- 108 Compare Protons of all elements →
- Neutrons
- 161 Compare Neutrons of all elements →
- Known isotopes
- 18 Compare Known isotopes of all elements →
- Stable isotopes
- 0 Compare Stable isotopes of all elements →
- Mass number (most stable)
- 270
- Most stable isotope
- Hs-269
- Discovery year
- 1984
Abundance
N/A
Crystal Structure
N/A
Electronic Structure
- Electrons per shell
- 2, 8, 18, 32, 32, 14, 2 Compare Electrons per shell of all elements →
Identifiers
- CAS number
- 54037-57-9 Compare CAS number of all elements →
- Term symbol
- 4
- InChI
- InChI=1S/Hs
- InChI Key
- OBDWMWVOVYJOMI-UHFFFAOYSA-N
Electron Configuration Predicted
Hs: 5f¹⁴ 6d⁶ 7s²[Rn] 5f¹⁴ 6d⁶ 7s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶ 5f¹⁴ 6d⁶ 7s²Atomic model
Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.
Schematic atomic model, not to scale.
Atomic Fingerprint
Emission / Absorption Spectrum
Isotope Distribution
No stable isotopes.
| Mass number | Atomic mass (u) | Natural abundance | Half-life |
|---|---|---|---|
| 273 Radioactive | 273.14168 ± 0.0004 | N/A | 1060 ms |
| 274 Radioactive | 274.1433 ± 0.00063 | N/A | 500 ms |
| 275 Radioactive | 275.14667 ± 0.00063 | N/A | 280 ms |
| 276 Radioactive | 276.14846 ± 0.00086 | N/A | 100 ms |
| 280 Radioactive | 280.159335 ± 0.000644 | N/A | 100 ms |
Phase / State
Phase/state data not available
Atomic Spectra
Showing 10 of 97. Sorted by ion charge (ascending).
Levels Holdings ?
| Ion | Charge | Levels |
|---|---|---|
| Hs I | 0 | 2 |
| Hs II | +1 | 2 |
| Hs III | +2 | 2 |
| Hs IV | +3 | 2 |
| Hs V | +4 | 2 |
| Hs VI | +5 | 2 |
| Hs VII | +6 | 2 |
| Hs VIII | +7 | 2 |
| Hs IX | +8 | 2 |
| Hs X | +9 | 2 |
Phase/state data not available
Compounds
Isotopes (5)
| Mass number | Atomic mass (u) | Natural abundance | Half-life | Decay mode | |
|---|---|---|---|---|---|
| 273 Radioactive | 273.14168 ± 0.0004 | N/A | 1060 ms | α ≈100%SF ? | |
| 274 Radioactive | 274.1433 ± 0.00063 | N/A | 500 ms | α ?SF ? | |
| 275 Radioactive | 275.14667 ± 0.00063 | N/A | 280 ms | α =100% | |
| 276 Radioactive | 276.14846 ± 0.00086 | N/A | 100 ms | α ?SF ? | |
| 280 Radioactive | 280.159335 ± 0.000644 | N/A | 100 ms | α ?SF ? |
Extended Properties
Covalent Radii (Extended)
- Covalent radius (Pyykkö)
- 134 pm
- Covalent radius (Pyykkö, double)
- 125 pm
- Covalent radius (Pyykkö, triple)
- 118 pm
Numbering Scales
- Mendeleev
- 62
Polarizability & Dispersion
- Dipole polarizability
- 36 a.u.
- Dipole polarizability (unc.)
- 4 a.u.
Oxidation State Categories
Advanced Reference Data
Isotope Decay Modes (33)
| Isotope | Mode | Intensity |
|---|---|---|
| 263 | A | 100% |
| 263 | SF | — |
| 264 | A | 70% |
| 264 | SF | 30% |
| 265 | A | 100% |
| 265 | SF | — |
| 266 | A | 76% |
| 266 | SF | 24% |
| 267 | A | 80% |
| 267 | SF | — |
Additional Data
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
Not Applicable
References (1)
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
Not Applicable
References (1)
References
(8)
Data deposited in or computed by PubChem
The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.
Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.
The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.
Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/
The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.
The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database
This section provides all form of data related to element Hassium.