Bohrium (Bh)
transition-metalSolid
Masse atomique relative standard
[270]Configuration électronique
[Rn] 7s2 5f14 6d5Point de fusion
N/DPoint d’ébullition
N/DMasse volumique
3,71e+4 kg/m³États d’oxydation
+3, +4, +5, +7Électronégativité (Pauling)
N/DÉnergie d’ionisation (1re)
7,7 eVAnnée de découverte
1976Rayon atomique
128 pmDétails
Bohrium is a synthetic transactinide element in group 7, below rhenium. It has no stable isotopes and has been made only atom by atom in heavy-ion nuclear reactions or as decay products of heavier superheavy nuclei. Its chemistry is known from a small number of rapid experiments and is consistent with a very heavy group 7 metal, with the +7 state especially important. No natural role or technological use is known.
Bohrium does not occur naturally in the Earth’s crust. Bohrium was first synthesized by German scientists at the GSI Center for Heavy Ion Research in Darmstadt, Germany in 1981 using the nuclear reaction 209Bi (54Cr, n) 262Bh. The element is named for Niels Bohr (Fig. IUPAC.107.1), the Nobel Prize winning physicist [649], [650]. Bohrium has no known isotopic applications aside from scientific research.
Bohrium is named after Niels Bohr.
First produced in 1976 by scientists working at the Joint Institute for Nuclear Research in Dubna, Russia, and later confirmed in 1981 by Peter Armbruster, Gottfried Münzenber and their team working at the Gesellschaft für Schwerionenforschung in Darmstadt, Germany, bohrium was produced by bombarding a target of bismuth-209 with ions of chromium-54. Bohrium's most stable isotope, bohrium-270, has a half-life of about 1 minute. It decays into dubnium-266 through alpha decay.
Formally known as Ns, Nielsbohrium
In 1976 Soviet scientists at Dubna announced they had synthesized element 107 by bombarding 204Bi with heavy nuclei of 54Cr. Reports say that experiments in 1975 had allowed scientists "to glimpse" the new element for 2/1000 s. A rapidly rotating cylinder, coated with a thin layer of bismuth metal, was used as a target. This was bombarded by a stream of 54Cr ions fired tangentially.
The existence of element 107 was confirmed by a team of West German physicists at the Heavy Ion Research Laboratory at Darmstadt, who created and identified six nuclei of element 107.
No macroscopic sample of bohrium has been prepared, so its visible appearance is unknown. It is expected from periodic trends and calculations to be a dense metallic solid under ordinary conditions, but this has not been directly observed.
Bohrium has no practical use outside scientific research. Its isotopes are used as subjects in nuclear-structure studies, decay-chain assignments, and tests of models for superheavy-element stability. Chemical experiments with individual atoms have also used bohrium to examine whether group trends continue into the 6d transition series. The element is not available for devices, materials, medicine, or industrial chemistry.
Since only a few atoms of bohrium have ever been made, there are currently no uses for bohrium outside of basic scientific research.
No weighable bohrium compound has been isolated. The best established chemical evidence concerns bohrium in the +7 oxidation state, especially a volatile oxychloride assigned as bohrium oxychloride, BhO₃Cl, formed and transported in gas-phase atom-at-a-time experiments. Its behavior resembles that of rhenium oxychloride, ReO₃Cl, supporting placement in group 7. Other oxidation states and compounds, including oxides and halides, are predicted by analogy and relativistic calculations but remain poorly characterized experimentally.
See more information at the Bohrium compound page.
Bohrium isotopes are radioactive and decay by alpha emission or spontaneous fission, depending on the isotope. Because only a few atoms are produced, chemical toxicity has not been measured and is not a practical exposure issue outside specialized laboratories. The main hazards in production experiments are ionizing radiation, activated targets and equipment, and decay products handled under accelerator radiological controls.
Bohrium has no known natural occurrence and no environmental cycle. Any atom released from an experiment would decay rapidly to other nuclides, so persistence, transport, and bioaccumulation of elemental bohrium have not been observed. Its environmental relevance is therefore limited to controlled research facilities and the management of radioactive activation products from those facilities.
Bohrium has no commodity market, commercial supply chain, or recoverable inventory. It is produced in accelerator experiments by fusing heavy target nuclei with ion beams, for example in reactions involving bismuth or actinide targets, or it appears in decay chains of heavier synthetic elements. Production yields are at the level of individual atoms, and separation is performed only for immediate detection or chemical study. Economic considerations are those of superheavy-element research infrastructure rather than material demand, substitution, or recycling.
Obtained by bombarding bismuth-204 with chromium-54.
Bohrium is not expected to survive as a primordial element because all known and predicted accessible isotopes are far too short-lived on geological or cosmic timescales. Superheavy nuclei near bohrium could be formed transiently in extreme neutron-rich nucleosynthesis, but no extraterrestrial bohrium has been detected. Claims about longer-lived superheavy nuclei remain theoretical for this element.
- Bohrium is named for Niels Bohr, with the spelling chosen to fit the usual element-name ending.
- The accepted symbol is Bh; the temporary systematic name was unniseptium.
- Unambiguous identification relies on correlated decay chains, not on collecting visible material.
- Atom-at-a-time chemistry showed bohrium behaves more like rhenium than like a chemically anomalous outlier.
- The first confirmed syntheses used cold-fusion heavy-ion reactions.
Images
Propriétés
Propriétés physiques
- Rayon atomique (empirique)
- 128 pm Comparer : Rayon atomique (empirique) de tous les éléments →
- Masse volumique
- 3,71 × 104 kg/m³ Comparer : Masse volumique de tous les éléments →
Propriétés chimiques
- Affinité électronique
- 0,44 eV
- Énergie d’ionisation (1re)
- 7,7 eV Comparer : Énergie d’ionisation (1re) de tous les éléments →
- Énergie d’ionisation (2e)
- 17,50006 eV Comparer : Énergie d’ionisation (2e) de tous les éléments →
- Énergie d’ionisation (3e)
- 26,700092 eV Comparer : Énergie d’ionisation (3e) de tous les éléments →
- Énergie d’ionisation (4e)
- 37,300128 eV Comparer : Énergie d’ionisation (4e) de tous les éléments →
- Énergie d’ionisation (5e)
- 49,000169 eV Comparer : Énergie d’ionisation (5e) de tous les éléments →
- États d’oxydation
- +3, +4, +5, +7 Comparer : États d’oxydation de tous les éléments →
- Électrons de valence
- 7 Comparer : Électrons de valence de tous les éléments →
- Configuration électronique
- [Rn] 7s2 5f14 6d5
Propriétés thermodynamiques
N/D
Propriétés nucléaires
- Protons
- 107 Comparer : Protons de tous les éléments →
- Neutrons
- 163 Comparer : Neutrons de tous les éléments →
- Isotopes connus
- 19 Comparer : Isotopes connus de tous les éléments →
- Isotopes stables
- 0 Comparer : Isotopes stables de tous les éléments →
- Nombre de masse (isotope le plus stable)
- 270
- Isotope le plus stable
- Bh-270
- Année de découverte
- 1976
Abondance
N/D
Structure cristalline
N/D
Structure électronique
- Électrons par couche
- 2, 8, 18, 32, 32, 13, 2 Comparer : Électrons par couche de tous les éléments →
Identifiants
- Numéro CAS
- 54037-14-8 Comparer : Numéro CAS de tous les éléments →
- Symbole de terme
- 5/2
- InChI
- InChI=1S/Bh
- Clé InChI
- INOXRQQPOOCQPH-UHFFFAOYSA-N
Configuration électronique Prédit
Bh: 5f¹⁴ 6d⁵ 7s²[Rn] 5f¹⁴ 6d⁵ 7s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶ 5f¹⁴ 6d⁵ 7s²Modèle atomique
Les isotopes diffèrent par leur nombre de neutrons, leur masse et leur stabilité — pas par la configuration électronique de l’atome neutre.
Modèle atomique schématique, non à l’échelle.
Empreinte atomique
Spectre d’émission / d’absorption
Distribution isotopique
Aucun isotope stable.
| Nombre de masse | Masse atomique (u) | Abondance naturelle | Demi-vie |
|---|---|---|---|
| 263 Radioactif | 263,12292 ± 0,00033 | N/D | 200 ms |
| 268 Radioactif | 268,12969 ± 0,00041 | N/D | 190 secondes |
| 262 Radioactif | 262,12297 ± 0,00033 | N/D | 84 ms |
| 276 Radioactif | 276,149169 ± 0,000644 | N/D | 60 secondes |
| 274 Radioactif | 274,14355 ± 0,00065 | N/D | 57 secondes |
Phase / État
Données de phase ou d’état indisponibles
Spectres atomiques
Affichage de 10 sur 96. Tri par charge ionique croissante.
Niveaux répertoriés ?
| Ion | Charge | Niveaux |
|---|---|---|
| Bh I | 0 | 2 |
| Bh II | +1 | 2 |
| Bh III | +2 | 2 |
| Bh IV | +3 | 2 |
| Bh V | +4 | 2 |
| Bh VI | +5 | 2 |
| Bh VII | +6 | 2 |
| Bh VIII | +7 | 2 |
| Bh IX | +8 | 2 |
| Bh X | +9 | 2 |
Données de phase ou d’état indisponibles
Composés
Isotopes (5)
| Nombre de masse | Masse atomique (u) | Abondance naturelle | Demi-vie | Mode de désintégration | |
|---|---|---|---|---|---|
| 263 Radioactif | 263,12292 ± 0,00033 | N/D | 200 ms | α ? | |
| 268 Radioactif | 268,12969 ± 0,00041 | N/D | 190 secondes | α ?SF ? | |
| 262 Radioactif | 262,12297 ± 0,00033 | N/D | 84 ms | α ≈100%SF<20% | |
| 276 Radioactif | 276,149169 ± 0,000644 | N/D | 60 secondes | α ?SF ? | |
| 274 Radioactif | 274,14355 ± 0,00065 | N/D | 57 secondes | α =100% |
Propriétés étendues
Rayons covalents (données étendues)
- Rayon covalent (Pyykkö)
- 141 pm
- Rayon covalent (Pyykkö, liaison double)
- 128 pm
- Rayon covalent (Pyykkö, liaison triple)
- 119 pm
Échelles de numérotation
- Mendeleev
- 58
Polarisabilité et dispersion
- Polarisabilité dipolaire
- 38 a.u.
- Polarisabilité dipolaire (incertitude)
- 4 a.u.
Catégories d’états d’oxydation
Données de référence avancées
Modes de désintégration des isotopes (32)
| Isotope | Mode | Intensité |
|---|---|---|
| 260 | A | 100% |
| 260 | B+ | — |
| 260 | SF | — |
| 261 | A | 100% |
| 261 | SF | — |
| 262 | A | 100% |
| 262 | SF | 20% |
| 263 | A | — |
| 264 | A | 86% |
| 264 | SF | 14% |
Données complémentaires
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
Not Applicable
Références (1)
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
Not Applicable
Références (1)
Références
(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.
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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 Bohrium.