Neptunium (Np)
actinideSolid
मानक परमाणु भार
[237]इलेक्ट्रॉन विन्यास
[Rn] 7s2 5f4 6d1गलनांक
643.85 °Cक्वथनांक
3901.85 °Cघनत्व
2.025e+4 kg/m³ऑक्सीकरण अवस्थाएँ
+2, +3, +4, +5, +6, +7विद्युतऋणात्मकता (पॉलिंग)
1.36आयनन ऊर्जा (प्रथम)
6.265608 eVखोज का वर्ष
1940परमाणु त्रिज्या
175 pmविवरण
Neptunium is a radioactive actinide and the first transuranium element. It is produced mainly by neutron reactions involving uranium in nuclear reactors and occurs naturally only in minute amounts from neutron capture and decay processes in uranium ores. Its chemistry bridges uranium and plutonium, with several accessible oxidation states in solution. The isotope ²³⁷Np is the most important for handling and study because of its long half-life and availability as a reactor by-product.
Neptunium metal buttons (photo courtesy Lawrence Berkeley National Laboratory)
Neptunium was first produced by Edwin M. McMillian and Philip H. Abelson, working at the University of California, Berkeley, in 1940. They produced neptunium-239, an isotope of neptunium with a half-life of about 2.4 days, by bombarding uranium with slow moving neutrons.
Named for the planet Neptune (named after the Roman god of the sea), the next planet out from the Sun after Uranus. There were many early false reports of the discovery of neptunium. The most significant was by Enrico Fermi who believed that bombarding uranium with neutrons followed by beta decay would lead to the formation of element 93. In 1934, he bombarded uranium atoms with neutrons and reported that he had produced elements 93 and 94. As it turned out, Fermi had actually fissioned or split uranium atoms into many fragment radioisotopes. The explanation and announcement of the discovery of fission was later published by Hahn and Strassman, although it was their co-worker Lisa Meitner who had correctly interpreted the results of the experiments. In 1940, with excitement about fission reaching the University of California at Berkeley, Professor Edwin McMillan and graduate student Philip Abelson bombarded uranium with cyclotron-produced moderated (slow) neutrons, resulting not in “fission” but "fusion" of the reactants forming the new element 93, which they named "neptunium":
23892U + 10n → 23992U → 23993Np + β-
Neptunium-239 was the first transuranium element produced synthetically and the first actinide series transuranium element discovered. This isotope has a beta-decay half-life of 2.3565 days, which forms daughter product plutonium-239 with a half-life of 24,000 years.
Metallic neptunium has been prepared in visible quantities. Fresh metal is silvery, dense, and chemically reactive, but it tarnishes in air as oxide layers form. It has several solid allotropes, and bulk physical measurements are limited by radioactivity, scarcity, and self-heating.
Neptunium has no broad commercial use as an element. ²³⁷Np is used in research on actinide chemistry, nuclear fuel cycles, and long-lived radioactive waste behavior. It is also the principal target material for producing ²³⁸Pu by neutron irradiation; ²³⁸Pu is then used in radioisotope heat sources and power systems. Small quantities of neptunium compounds have been used as analytical standards and in radiochemical method development.
Neptunium's most stable isotope, neptunium-237, has a half-life of about 2,144,000 years. It decays into protactinium-233 through alpha decay. Neptunium-237, which is produced in gram quantities as a by-product of the production of plutonium in nuclear reactors, is used in neutron detectors.
Once considered to be completely artificial, extremely small amounts of neptunium are produced naturally in uranium ores through the interaction of atoms of uranium in the ore with neutrons produced by the decay of other atoms of uranium in the ore.
Isotopes in Industry
237Np (with a half-life of 2.14×106 years) is fissionable, meaning that neptunium can be bombarded with neutrons and, as a result, create more neutrons that are free to interact with nearby material and can be used in fast neutron reactors or in nuclear weapons (Fig. IUPAC.93.1) [75] J. Peterson, M. McDonell, L. Haroun, F. Monette, R. D. Hildebrand, A. Taboas. Radiological and Chemical Fact Sheets to Support Health Risk Analyses for Contaminated Areas, Prepared by Argonne National Laboratory Environmental Science Division in collaboration with U.S. Department of Energy, Richland Operations Office and Chicago Operations Office (2014), Feb. 22; http://www.remm.nlm.gov/ANL_ContaminantFactSheets_All_070418.pdf., [603] P. Weiss. Science News.162, 259 (2002)., [604] T. Kenna. J. Anal. At. Spectrom.17, 1471 (2002).. 237Np is used in neutron detection instruments [75] J. Peterson, M. McDonell, L. Haroun, F. Monette, R. D. Hildebrand, A. Taboas. Radiological and Chemical Fact Sheets to Support Health Risk Analyses for Contaminated Areas, Prepared by Argonne National Laboratory Environmental Science Division in collaboration with U.S. Department of Energy, Richland Operations Office and Chicago Operations Office (2014), Feb. 22; http://www.remm.nlm.gov/ANL_ContaminantFactSheets_All_070418.pdf..
Isotopes Used as a Source of Radioactive Isotope(s)
237Np is used in the production of 238Pu (with a half-life of 87.7 years), which is an emitter of alpha particles used in thermoelectric generators and radioisotope-heater units. When 237Np captures a neutron, it becomes 238Np, with a half-life of 2.117 days, which decays to 238Pu [75] J. Peterson, M. McDonell, L. Haroun, F. Monette, R. D. Hildebrand, A. Taboas. Radiological and Chemical Fact Sheets to Support Health Risk Analyses for Contaminated Areas, Prepared by Argonne National Laboratory Environmental Science Division in collaboration with U.S. Department of Energy, Richland Operations Office and Chicago Operations Office (2014), Feb. 22; http://www.remm.nlm.gov/ANL_ContaminantFactSheets_All_070418.pdf..
Neptunium forms compounds in oxidation states from +3 to +7, with +4, +5, and +6 especially important in aqueous chemistry. The neptunyl ion NpO₂⁺ is a characteristic +5 species and is often relatively mobile in oxidizing waters, while NpO₂²⁺ represents +6 chemistry. Neptunium dioxide NpO₂ is a stable refractory oxide and an important solid phase. Halides such as neptunium tetrachloride NpCl₄ and neptunium hexafluoride NpF₆ illustrate the element’s actinide-like coordination and redox behavior.
See more information at the Neptunium compound page.
All neptunium isotopes are radioactive, and hazards depend strongly on isotope, chemical form, and exposure route. ²³⁷Np emits mainly alpha radiation with associated gamma emissions from decay products, so ingestion, inhalation, or contamination of wounds is the principal concern. Finely divided metal and soluble compounds require strict radiological containment. External dose rates can be significant for some samples because of accompanying gamma-emitting impurities or daughters.
Natural neptunium is extremely scarce, but anthropogenic neptunium occurs in spent nuclear fuel, reprocessing wastes, and fallout residues. Environmental behavior is controlled by oxidation state, complexation, mineral sorption, and reducing conditions. Np(V) as NpO₂⁺ can migrate more readily than many tetravalent actinides, whereas Np(IV) tends to form less soluble solids or strongly sorbed species. Its long half-life makes it important in repository performance assessments.
Neptunium is not traded as a commodity and has no ordinary industrial supply chain. Recoverable ²³⁷Np is generated as a by-product in irradiated uranium fuel and can be separated only in specialized nuclear facilities under heavy regulation. Demand is small and centered on research inventories and on target preparation for ²³⁸Pu production. Costs are dominated by radiochemical separation, safeguards, licensing, waste management, and secure storage rather than by ore mining or conventional refining.
Produced by bombarding uranium with slow neutrons.
Neptunium has no stable isotopes, so any primordial neptunium has decayed away. It can be formed in trace amounts by neutron capture in uranium-bearing materials and in nuclear explosions or reactors, and transient neptunium isotopes may occur in astrophysical rapid neutron-capture processes. Its extraterrestrial abundance is effectively negligible compared with long-lived actinides such as uranium and thorium.
- Neptunium was named after Neptune, following uranium’s naming after Uranus.
- ²³⁷Np has a half-life of about 2.14 million years.
- Neptunium was the first element beyond uranium to be identified.
- NpF₆ is volatile, a property relevant to actinide fluoride chemistry.
- The common aqueous Np(V) ion is linear neptunyl, NpO₂⁺.
- Separated neptunium metal darkens on exposure to air.
चित्र
गुण
भौतिक
- परमाणु त्रिज्या (आनुभविक)
- 175 pm सभी तत्वों की परमाणु त्रिज्या (आनुभविक) की तुलना करें →
- सहसंयोजक त्रिज्या
- 190 pm सभी तत्वों की सहसंयोजक त्रिज्या की तुलना करें →
- वान डर वाल्स त्रिज्या
- 221 pm सभी तत्वों की वान डर वाल्स त्रिज्या की तुलना करें →
- घनत्व
- 2.025 × 104 kg/m³ सभी तत्वों की घनत्व की तुलना करें →
- मोलर आयतन
- 0.0211 L/mol
- STP पर प्रावस्था
- ठोस सभी तत्वों की STP पर प्रावस्था की तुलना करें →
- गलनांक
- 643.85 °C सभी तत्वों की गलनांक की तुलना करें →
- क्वथनांक
- 3901.85 °C सभी तत्वों की क्वथनांक की तुलना करें →
- क्रिस्टल संरचना
- विषमलंबाक्ष सभी तत्वों की क्रिस्टल संरचना की तुलना करें →
रासायनिक
- विद्युतऋणात्मकता (पॉलिंग)
- 1.36 सभी तत्वों की विद्युतऋणात्मकता (पॉलिंग) की तुलना करें →
- इलेक्ट्रॉन बंधुता
- 0.48 eV
- आयनन ऊर्जा (प्रथम)
- 6.265608 eV सभी तत्वों की आयनन ऊर्जा (प्रथम) की तुलना करें →
- आयनन ऊर्जा (द्वितीय)
- 11.50004 eV सभी तत्वों की आयनन ऊर्जा (द्वितीय) की तुलना करें →
- आयनन ऊर्जा (तृतीय)
- 19.700068 eV सभी तत्वों की आयनन ऊर्जा (तृतीय) की तुलना करें →
- आयनन ऊर्जा (चतुर्थ)
- 33.800116 eV सभी तत्वों की आयनन ऊर्जा (चतुर्थ) की तुलना करें →
- आयनन ऊर्जा (पंचम)
- 48.000165 eV सभी तत्वों की आयनन ऊर्जा (पंचम) की तुलना करें →
- ऑक्सीकरण अवस्थाएँ
- +2, +3, +4, +5, +6, +7 सभी तत्वों की ऑक्सीकरण अवस्थाएँ की तुलना करें →
- संयोजकता इलेक्ट्रॉन
- 3 सभी तत्वों की संयोजकता इलेक्ट्रॉन की तुलना करें →
- इलेक्ट्रॉन विन्यास
- [Rn] 7s2 5f4 6d1
ऊष्मागतिक
- गलन ऊष्मा
- 0.10364305 eV सभी तत्वों की गलन ऊष्मा की तुलना करें →
- वाष्पन ऊष्मा
- 3.482407 eV सभी तत्वों की वाष्पन ऊष्मा की तुलना करें →
- ऊर्ध्वपातन ऊष्मा
- 4.33228 eV
- परमाणुकरण ऊष्मा
- 4.33228 eV
- परमाणुकरण एन्थैल्पी
- 4.817329 eV
नाभिकीय
- प्रोटॉन
- 93 सभी तत्वों की प्रोटॉन की तुलना करें →
- न्यूट्रॉन
- 144 सभी तत्वों की न्यूट्रॉन की तुलना करें →
- ज्ञात समस्थानिक
- 27 सभी तत्वों की ज्ञात समस्थानिक की तुलना करें →
- स्थिर समस्थानिक
- 0 सभी तत्वों की स्थिर समस्थानिक की तुलना करें →
- द्रव्यमान संख्या (सबसे स्थिर)
- 237
- सबसे स्थिर समस्थानिक
- Np-237
- खोज का वर्ष
- 1940
प्रचुरता
उपलब्ध नहीं
क्रिस्टल संरचना
- जालक स्थिरांक a
- 472 pm
इलेक्ट्रॉनिक संरचना
- प्रति कोश इलेक्ट्रॉन
- 2, 8, 18, 32, 22, 9, 2 सभी तत्वों की प्रति कोश इलेक्ट्रॉन की तुलना करें →
पहचानकर्ता
- CAS संख्या
- 7439-99-8 सभी तत्वों की CAS संख्या की तुलना करें →
- टर्म प्रतीक
- 6L11/2
- InChI
- InChI=1S/Np
- InChI कुंजी
- LFNLGNPSGWYGGD-UHFFFAOYSA-N
इलेक्ट्रॉन विन्यास मापित
Np: 5f⁴ 6d¹ 7s²[Rn] 5f⁴ 6d¹ 7s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶ 5f⁴ 6d¹ 7s²परमाणु मॉडल
समस्थानिक न्यूट्रॉन की संख्या, द्रव्यमान और स्थिरता बदलते हैं — उदासीन परमाणु का इलेक्ट्रॉन विन्यास नहीं।
सांकेतिक परमाणु मॉडल, वास्तविक अनुपात में नहीं।
परमाणु पहचान-चिह्न
उत्सर्जन / अवशोषण स्पेक्ट्रम
समस्थानिक वितरण
कोई स्थिर समस्थानिक नहीं है।
| द्रव्यमान संख्या | परमाणु द्रव्यमान (u) | प्राकृतिक प्रचुरता | अर्धायु |
|---|---|---|---|
| 219 रेडियोधर्मी | 219.03143 ± 0.00021 | उपलब्ध नहीं | 570 us |
| 227 रेडियोधर्मी | 227.034957 ± 0.000078 | उपलब्ध नहीं | 510 ms |
| 222 रेडियोधर्मी | 222.0333 ± 0.00021 | उपलब्ध नहीं | 480 ns |
| 235 रेडियोधर्मी | 235.0440635 ± 0.0000021 | उपलब्ध नहीं | 396.1 दिन |
| 236 रेडियोधर्मी | 236.04657 ± 0.000054 | उपलब्ध नहीं | 153 ky |
प्रावस्था / अवस्था
कारण: गलनांक (643.85 °C) से 618.9 °C कम
सांकेतिक, वास्तविक अनुपात में नहीं
प्रावस्था संक्रमण बिंदु
संक्रमण ऊर्जाएँ
गलनांक पर 1 mol को पिघलाने के लिए आवश्यक ऊर्जा
क्वथनांक पर 1 mol को वाष्पित करने के लिए आवश्यक ऊर्जा
ऊर्ध्वपातनांक पर 1 mol के ऊर्ध्वपातन के लिए आवश्यक ऊर्जा
घनत्व
मानक परिस्थितियों में
मानक परिस्थितियों में
परमाणु स्पेक्ट्रम
93 में से 10 दिखाए जा रहे हैं। आयन के आवेश के अनुसार आरोही क्रम में व्यवस्थित।
उपलब्ध स्पेक्ट्रमी रेखा डेटा ?
| आयन | आवेश | कुल रेखाएँ | संक्रमण प्रायिकताएँ | स्तर पदनाम |
|---|---|---|---|---|
| Np I | 0 | 96 | 0 | 0 |
उपलब्ध ऊर्जा स्तर डेटा ?
| आयन | आवेश | स्तर |
|---|---|---|
| Np I | 0 | 2 |
| Np II | +1 | 2 |
| Np III | +2 | 2 |
| Np IV | +3 | 2 |
| Np V | +4 | 2 |
| Np VI | +5 | 2 |
| Np VII | +6 | 2 |
| Np VIII | +7 | 2 |
| Np IX | +8 | 2 |
| Np X | +9 | 2 |
आयनिक त्रिज्याएँ
| आवेश | उपसहसंयोजन | प्रचक्रण | त्रिज्या |
|---|---|---|---|
| +2 | 6 | उपलब्ध नहीं | 110.00000000000001 pm |
| +3 | 6 | उपलब्ध नहीं | 101 pm |
| +3 | 9 | उपलब्ध नहीं | 117.8 pm |
| +4 | 6 | उपलब्ध नहीं | 87 pm |
| +4 | 8 | उपलब्ध नहीं | 98 pm |
| +5 | 6 | उपलब्ध नहीं | 75 pm |
| +6 | 6 | उपलब्ध नहीं | 72 pm |
| +7 | 6 | उपलब्ध नहीं | 71 pm |
यौगिक
समस्थानिक (5)
There are 25 known radioactive isotopes of neptunium ranging in atomic weights from 225 to 244 with 5 of those as metastable isotopes. The most stable are Np-237 with a half-life of 2.14 million years; Np-236 with a half-life of 154,000 years; and Np-235 with a half-life of 396 days. All of the remaining isotopes have half-lives less than 4.5 days, with most less than 50 minutes. The primary decay mode for isotopes lighter than 237Np is by electron capture with a great deal of alpha emission. The products are mostly isotopes of uranium. The primary decay mode for Np-237 is by alpha-decay forming protactinium. The primary decay mode for the isotopes heavier than Np-237 is by beta-decay, forming plutonium. Neptunium-237, after decaying to protactinium then to uranium, eventually decays to form bismuth-209 and thallium-205. Unlike most other common heavy nuclei which decay to make isotopes of lead this decay chain is known as the neptunium series.
| द्रव्यमान संख्या | परमाणु द्रव्यमान (u) | प्राकृतिक प्रचुरता | अर्धायु | क्षय का प्रकार | |
|---|---|---|---|---|---|
| 219 रेडियोधर्मी | 219.03143 ± 0.00021 | उपलब्ध नहीं | 570 us | α =100% | |
| 227 रेडियोधर्मी | 227.034957 ± 0.000078 | उपलब्ध नहीं | 510 ms | α ≈100%β+ ? | |
| 222 रेडियोधर्मी | 222.0333 ± 0.00021 | उपलब्ध नहीं | 480 ns | α =100% | |
| 235 रेडियोधर्मी | 235.0440635 ± 0.0000021 | उपलब्ध नहीं | 396.1 दिन | ε =99.99740±1.3%α =0.00260±1.3% | |
| 236 रेडियोधर्मी | 236.04657 ± 0.000054 | उपलब्ध नहीं | 153 ky | ε =86.3±0.8%β- =13.5±0.8%α =0.16±0.4% |
विस्तृत गुण
सहसंयोजक त्रिज्याएँ (विस्तृत)
- सहसंयोजक त्रिज्या (प्यूक्को)
- 171 pm
- सहसंयोजक त्रिज्या (प्यूक्को, द्विबंध)
- 136 pm
- सहसंयोजक त्रिज्या (प्यूक्को, त्रिबंध)
- 116 pm
वान डर वाल्स त्रिज्याएँ
- Alvarez
- 282 pm
- UFF
- 342.4 pm
- MM3
- 252 pm
परमाणु और धात्विक त्रिज्याएँ
- परमाणु त्रिज्या (राह्म)
- 281 pm
संख्यांकन मापक्रम
- Mendeleev
- 22
- Pettifor
- 44
- Glawe
- 37
विद्युतऋणात्मकता मापक्रम
- Ghosh
- 0
ध्रुवणीयता और परिक्षेपण
- द्विध्रुव ध्रुवणीयता
- 151 a.u.
- द्विध्रुव ध्रुवणीयता (अनिश्चितता)
- 20 a.u.
प्रावस्था संक्रमण और अपररूप
| गलनांक | 917.15 K |
ऑक्सीकरण अवस्था की श्रेणियाँ
उन्नत संदर्भ डेटा
क्रिस्टल त्रिज्याओं का विवरण (8)
| आवेश | CN | प्रचक्रण | rcrystal (pm) | उत्पत्ति |
|---|---|---|---|---|
| 2 | VI | 124 | ||
| 3 | VI | 115 | from r^3 vs V plots, | |
| 4 | VI | 101 | from r^3 vs V plots, | |
| 4 | VIII | 112 | from r^3 vs V plots, | |
| 5 | VI | 89 | ||
| 6 | VI | 86 | from r^3 vs V plots, | |
| 7 | VI | 85 | Ahrens (1952) ionic radius, | |
| 3 | IX | — | 131.8 |
समस्थानिक क्षय के प्रकार (44)
| समस्थानिक | मोड | तीव्रता |
|---|---|---|
| 219 | A | 100% |
| 220 | A | 100% |
| 221 | A | — |
| 222 | A | 100% |
| 223 | A | 100% |
| 224 | A | 100% |
| 225 | A | 100% |
| 225 | B+ | — |
| 226 | A | 100% |
| 226 | B+ | — |
अतिरिक्त डेटा
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
Not Applicable
संदर्भ (1)
- [5] Neptunium https://education.jlab.org/itselemental/ele093.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
Not Applicable
संदर्भ (1)
- [5] Neptunium https://education.jlab.org/itselemental/ele093.html
संदर्भ
(9)
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 Neptunium.
The element property data was retrieved from publications.