Dubnium (Db)
transition-metalSolid
標準原子量
[268]電子配置
[Rn] 7s2 5f14 6d3融点
データなし沸点
データなし密度
2.93e+4 kg/m³酸化数
+3, +4, +5電気陰性度（Pauling）
データなし第1イオン化エネルギー
6.8 eV発見年
1967原子半径
139 pm詳細
Dubnium is a synthetic transactinide element in group 5, below tantalum. It is known only from accelerator-produced atoms of radioactive isotopes, so its chemistry is studied by rapid, highly sensitive methods rather than by weighing or handling bulk material. Its observed behavior is broadly consistent with a heavy group 5 element, though relativistic effects and nuclear instability make its chemistry experimentally difficult.
Dubnium does not occur naturally in the Earth’s crust. Credit for the first synthesis of this element is given jointly to Albert Ghiorso and his team at the University of California in Berkeley and Georgi Flerov and his team at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia (Fig. IUPAC.105.1). The element is named for the location of the Joint Institute for Nuclear Research (JINR) laboratory in Dubna, Russia [646], [647]. Dubnium has no isotopic applications outside of scientific research.
Dubnium is named after the site of the Joint Institute for Nuclear Research in Dubna, Russia.
Scientists working at the Joint Institute for Nuclear Research in Dubna, Russia, first reported the production of dubnium in 1967. They bombarded atoms of americium-243 with ions of neon-22, forming atoms of dubnium-260 and five free neutrons and atoms of dubnium-261 and four free neutrons. In 1970, a group of scientists working at the Lawrence Radiation Laboratory, now known as the Lawrence Berkeley Laboratory, in Berkeley, California, bombarded atoms of californium-249 with ions of nitrogen-15, forming atoms of dubnium-260 and 4 free neutrons. Credit for the discovery of dubnium is still under debate. Dubnium's most stable isotope, dubnium-268, has a half-life of about 32 hours and decays through spontaneous fission.
In 1967 G.N. Flerov reported that a Soviet team working at the Joint Institute for Nuclear Research at Dubna may have produced a few atoms of 260105 and 261105 by bombarding 243Am with 22Ne. The evidence was based on time-coincidence measurements of alpha energies.
In 1970 Dubna scientists synthesized Element 105 and, by the end of April 1970, "had investigated all the types of decay of the new element and had determined its chemical properties," according to a report in 1970. The Soviet group had not proposed a name for 105. In late April 1970, it was announced that 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). When a15N 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.
Ghiorso and his associates have attempted to confirm Soviet findings by more sophisticated methods without success. The Berkeley Group proposed the name hahnium after the late German scientist Otto Hahn (1879-1968) and symbol Ha. However, the International Union of Pure and Applied Chemistry panel members in 1977 recommended that element 105 be named to Dubnium (symbol Db) after the site of the Joint Institute for Nuclear Research in Russia. Unfortunately, the name hahnium will not be used again according to the rules for naming new elements. Some scientists still use the earlier name of hahnium because it had been used for about 25 years.
No macroscopic sample of dubnium has been prepared, and its visible appearance is unknown. Metallic bulk properties such as color, density, melting point, and hardness are therefore predicted or extrapolated rather than directly measured.
Dubnium has no practical use outside scientific research. Its isotopes are produced in nuclear reaction experiments to study superheavy nuclei, decay chains, spontaneous fission, and the chemical behavior of the heaviest group 5 element. Individual atoms have also been used in comparative transactinide chemistry, where separation behavior is measured before radioactive decay. There are no commercial, industrial, medical, or consumer applications.
Due to the small amounts produced and its short half-life, there are currently no uses for dubnium outside of basic scientific research.
Dubnium chemistry has been investigated mainly in aqueous and gas-phase separation systems at the atom-at-a-time scale. The most accessible oxidation state is expected to be +5, by analogy with niobium and tantalum, and experiments support formation of group 5-like halide and oxyhalide species. Volatile dubnium pentachloride, DbCl₅, and dubnium oxychloride, DbOCl₃, are inferred in thermochromatography studies, although such species are not isolated as ordinary samples. Lower oxidation states remain poorly characterized.
See more information at the Dubnium compound page.
The safety hazards of dubnium are dominated by radioactivity rather than ordinary chemical toxicity. All known isotopes are short-lived, and some decay by alpha emission or spontaneous fission. The quantities made are far below macroscopic toxicological relevance, but accelerator targets, recoil products, and daughter nuclides require radiological controls. Isotope-specific half-lives and decay modes determine the actual hazard in an experiment.
Dubnium has no known natural environmental cycle. Any atoms formed in laboratories decay rapidly and are produced in quantities too small to create measurable environmental concentrations. Its environmental chemistry, mobility, and biological uptake have not been directly observed in bulk systems. If released from an experiment, its significance would be local and radiological, governed mainly by decay and containment of associated radioactive materials.
Dubnium has no commodity market, no industrial supply chain, and no role in trade or recycling. Production is limited to specialized heavy-ion accelerator experiments, typically by bombarding actinide or heavy-element targets with lighter ions and separating a few atoms from intense backgrounds. The limiting factors are accelerator time, target preparation, detection efficiency, and isotope half-life, not ore availability or conventional refining cost. Substitution is not relevant because its only use is as a research subject.
Made by bombarding californium-249 with a beam of nitrogen-15
Dubnium is not expected to occur naturally in detectable amounts in the universe because all known isotopes are too short-lived to survive since nucleosynthesis events. It may be formed transiently in extreme neutron-rich environments or in artificial nuclear reactions, but no extraterrestrial reservoir is known. Its cosmic abundance is effectively zero for practical purposes.
- Dubnium was named for Dubna, the Russian research center associated with early transactinide work.
- Its chemistry must often be completed in seconds or less after an atom is created.
- The longest-lived known dubnium isotopes still have half-lives far too short for stockpiling.
- Dubnium sits in group 5, but it cannot be studied by ordinary beaker-scale chemistry.
- Single-atom experiments compare where a dubnium atom travels, deposits, or elutes before it decays.
画像
性質
物理的性質
- 原子半径（経験値）
- 139 pm 全元素の原子半径（経験値）を比較 →
- 密度
- 2.93 × 104 kg/m³ 全元素の密度を比較 →
化学的性質
- 電子親和力
- 0.56 eV
- 第1イオン化エネルギー
- 6.8 eV 全元素の第1イオン化エネルギーを比較 →
- 第2イオン化エネルギー
- 14.000048 eV 全元素の第2イオン化エネルギーを比較 →
- 第3イオン化エネルギー
- 23.10008 eV 全元素の第3イオン化エネルギーを比較 →
- 第4イオン化エネルギー
- 33.000114 eV 全元素の第4イオン化エネルギーを比較 →
- 第5イオン化エネルギー
- 43.000148 eV 全元素の第5イオン化エネルギーを比較 →
- 酸化数
- +3, +4, +5 全元素の酸化数を比較 →
- 価電子
- 5 全元素の価電子を比較 →
- 電子配置
- [Rn] 7s2 5f14 6d3
熱力学的性質
データなし
原子核
- 陽子数
- 105 全元素の陽子数を比較 →
- 中性子数
- 163 全元素の中性子数を比較 →
- 既知の同位体
- 16 全元素の既知の同位体を比較 →
- 安定同位体
- 0 全元素の安定同位体を比較 →
- 質量数（最も安定な同位体）
- 268
- 最も安定な同位体
- Db-268
- 発見年
- 1967
存在度
データなし
結晶構造
データなし
電子構造
- 各電子殻の電子数
- 2, 8, 18, 32, 32, 11, 2 全元素の各電子殻の電子数を比較 →
識別子
- CAS登録番号
- 53850-35-4 全元素のCAS登録番号を比較 →
- 項記号
- 4F3/2
- InChI
- InChI=1S/Db
- InChI Key
- PUKKTGLVJQVIOF-UHFFFAOYSA-N
電子配置 予測値
Db: 5f¹⁴ 6d³ 7s²[Rn] 5f¹⁴ 6d³ 7s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶ 5f¹⁴ 6d³ 7s²原子モデル
同位体によって中性子数、質量、安定性は変わりますが、中性原子の電子配置は変わりません。
模式的な原子モデルです。実際の縮尺とは異なります。
原子の指紋
発光／吸収スペクトル
同位体分布
安定同位体はありません。
| 質量数 | 原子質量（u） | 天然存在比 | 半減期 |
|---|---|---|---|
| 259 放射性 | 259.109492 ± 0.000057 | データなし | 510 ms |
| 266 放射性 | 266.12103 ± 0.0003 | データなし | 80 分 |
| 255 放射性 | 255.10707 ± 0.00045 | データなし | 54 ms |
| 262 放射性 | 262.11407 ± 0.00015 | データなし | 34 秒 |
| 263 放射性 | 263.11499 ± 0.00018 | データなし | 29 秒 |
相／状態
相・状態のデータはありません
原子スペクトル
全94件中10件を表示しています。 イオンの電荷の昇順で並べています。
準位データの収録状況 ?
| イオン | 電荷 | 準位 |
|---|---|---|
| Db I | 0 | 2 |
| Db II | +1 | 2 |
| Db III | +2 | 2 |
| Db IV | +3 | 2 |
| Db V | +4 | 2 |
| Db VI | +5 | 2 |
| Db VII | +6 | 2 |
| Db VIII | +7 | 2 |
| Db IX | +8 | 2 |
| Db X | +9 | 2 |
相・状態のデータはありません
化合物
同位体 (5)
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 a 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 s. 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 s. Seven isotopes of element 105 (unnilpentium) are now recognized.
| 質量数 | 原子質量（u） | 天然存在比 | 半減期 | 崩壊形式 | |
|---|---|---|---|---|---|
| 259 放射性 | 259.109492 ± 0.000057 | データなし | 510 ms | α =100% | |
| 266 放射性 | 266.12103 ± 0.0003 | データなし | 80 分 | α ?SF =?β+ ? | |
| 255 放射性 | 255.10707 ± 0.00045 | データなし | 54 ms | SF ≈67%α ? | |
| 262 放射性 | 262.11407 ± 0.00015 | データなし | 34 秒 | SF =52±0.4%α =48±0.4%β+ ? | |
| 263 放射性 | 263.11499 ± 0.00018 | データなし | 29 秒 | SF =56±1.4%α =37±1.4%β+ =6.9±1.6% |
詳細な性質
共有結合半径（詳細）
- 共有結合半径（Pyykkö）
- 149 pm
- 共有結合半径（Pyykkö、二重結合）
- 136 pm
- 共有結合半径（Pyykkö、三重結合）
- 126 pm
番号付けの尺度
- Mendeleev
- 50
分極率と分散
- 双極子分極率
- 42 a.u.
- 双極子分極率（不確かさ）
- 4 a.u.
酸化数の分類
専門参考データ
同位体の崩壊形式 (35)
| 同位体 | モード | 強度 |
|---|---|---|
| 255 | SF | 67% |
| 255 | A | — |
| 256 | A | 70% |
| 256 | B+ | 30% |
| 256 | SF | — |
| 257 | A | 94% |
| 257 | SF | 6% |
| 257 | B+ | — |
| 258 | A | 64% |
| 258 | B+ | 36% |
追加データ
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
Not Applicable
参考文献 (1)
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
Not Applicable
参考文献 (1)
参考文献
(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 Dubnium.