Mendelevium (Md)
actinideSolid
प्रमाणित अणुभार
[258]इलेक्ट्रॉन संरूपण
[Rn] 7s2 5f13द्रवणांक
826.85 °Cउत्कलनांक
उपलब्ध नाहीघनता
1.03e+4 kg/m³ऑक्सिडीकरण अवस्था
+2, +3विद्युतऋणता (पॉलिंग)
1.3आयनीकरण ऊर्जा (पहिली)
6.58 eVशोधाचे वर्ष
1955अणुत्रिज्या
उपलब्ध नाहीतपशील
Mendelevium is a synthetic actinide and the first element that was initially identified one atom at a time. All known isotopes are radioactive, and none is present in nature in measurable primordial amounts. Its chemistry is dominated by the +3 oxidation state, broadly resembling neighboring late actinides and lanthanides, with a distinctive accessible +2 state under reducing conditions. Work on mendelevium is limited by very small samples and short half-lives.
Mendelevium does not occur naturally in the Earth’s crust. It was first synthesized in 1955 by Glenn T. Seaborg and his team at the University of California using the reactions 253Es (4He, n) 256Md and 253Es (4He, 2n) 255Md. Mendelevium is named for the Russian scientist, Dmitri Mendeleev (Fig. IUPAC.101.1), who developed the Periodic Table of the chemical elements [636], [637]. There are no applications for isotopes of mendelevium aside from scientific research.
Experiments seem to show that the element possesses a moderately stable dipositive (II) oxidation state in addition to the tripositive (III) oxidation state, which is characteristic of the actinide elements.
Mendelevium was first produced by Stanley G. Thompson, Glenn T. Seaborg, Bernard G. Harvey, Gregory R. Choppin and Albert Ghiorso working at the University of California, Berkeley, in 1955. They bombarded atoms of einsteinium-253 with helium ions using a device known as a cyclotron. This produced atoms of mendelevium-256, an isotope with a half-life of about 77 minutes, and a free neutron. Mendelevium's most stable isotope, mendelevium-258, has a half-life of about 51.5 days. It decays into einsteinium-254 through alpha decay or decays through spontaneous fission.
Mendelevium is named after Dmitri Mendeleev. It is the ninth transuranium element of the actinide series discovered. It was first identified by Ghiorso, Harvey, Choppin, Thompson, and Seaborg in early in 1955 during the bombardment of the isotope 253Es with helium ions in the Berkeley 60-inch cyclotron. The isotope produced was 256Md, which has a half-life of 76 min. This first identification was notable in that 256Md was synthesized on a one-atom-at-a-time basis.
No macroscopic sample of mendelevium has been isolated, so its real bulk appearance is unknown. A metallic solid is expected by periodic trends, but color, texture, density, and other ordinary bulk properties have not been directly measured.
Mendelevium has no practical use outside scientific research. Its isotopes are produced for nuclear-chemistry studies, tracer-scale separation experiments, and investigations of actinide electronic structure and redox behavior. Historically, mendelevium was important in demonstrating that new elements could be discovered and chemically characterized from only a few atoms. It is not used in medicine, industry, consumer products, or power generation.
Since only small amounts of mendelevium have ever been produced, it currently has no uses outside of basic scientific research.
256Md has been used to elucidate some of the chemical properties of mendelevium in aqueous solution.
Mendelevium chemistry has been studied in solution and on surfaces at tracer scale. The Md³⁺ ion is the most stable aqueous form and behaves much like a heavy trivalent actinide. The Md²⁺ ion can be produced by reduction and is unusually important for identifying mendelevium relative to many neighboring actinides. Simple compounds such as mendelevium(III) chloride, MdCl₃, and mendelevium(III) fluoride, MdF₃, are inferred or studied only in minute quantities; no bulk compound chemistry exists.
See more information at the Mendelevium compound page.
The main hazard from mendelevium is ionizing radiation, with risk depending strongly on isotope, activity, chemical form, and containment. The longest-lived isotope, ²⁵⁸Md, has a half-life of about 51 days, while many others decay much faster. Amounts normally handled are extremely small, but work requires specialized radiochemical facilities to prevent contamination and external or internal exposure.
Mendelevium has no significant natural environmental cycle. Any environmental presence would come from specialized nuclear research or decay chains in artificial material and would involve vanishingly small quantities. Because it is radioactive and produced atom by atom or in tracer amounts, its environmental chemistry is inferred mainly from actinide behavior rather than observed field distribution.
Mendelevium is not a traded commodity and has no commercial supply chain. It is made in high-flux reactors or particle accelerators by neutron capture and charged-particle nuclear reactions involving heavy actinide targets, followed by rapid radiochemical separation. Production yields are extremely small, often atom-scale to tracer-scale, and are constrained by target availability, irradiation time, isotope half-life, and the need for specialized laboratories. There is no meaningful recycling market or industrial substitution issue because demand is confined to research.
Made by bombarding einsteinium with helium ions.
Mendelevium is not expected to have appreciable cosmic abundance. Its isotopes have half-lives far too short to survive since stellar nucleosynthesis or Solar System formation. It may be formed transiently in extreme neutron-rich events or in artificial nuclear reactions, but any naturally produced atoms would decay quickly and would not accumulate in planets, meteorites, or interstellar matter.
- Mendelevium was named for Dmitri Mendeleev, the developer of the periodic table.
- The first identification used only about a few atoms produced by bombarding einsteinium.
- Its accessible +2 state is a key diagnostic feature in radiochemical separations.
- ²⁵⁶Md has been used in atom-at-a-time chemical studies despite its short half-life.
- No weighing, casting, or visual inspection of elemental mendelevium has been possible.
प्रतिमा
गुणधर्म
भौतिक
- व्हॅन डर वाल्स त्रिज्या
- 246 pm सर्व घटकांच्या व्हॅन डर वाल्स त्रिज्या ची तुलना करा →
- घनता
- 1.03 × 104 kg/m³ सर्व घटकांच्या घनता ची तुलना करा →
- STP येथे अवस्था
- घन सर्व घटकांच्या STP येथे अवस्था ची तुलना करा →
- द्रवणांक
- 826.85 °C सर्व घटकांच्या द्रवणांक ची तुलना करा →
रासायनिक
- विद्युतऋणता (पॉलिंग)
- 1.3 सर्व घटकांच्या विद्युतऋणता (पॉलिंग) ची तुलना करा →
- इलेक्ट्रॉन आसक्ती
- 0.997 eV
- आयनीकरण ऊर्जा (पहिली)
- 6.58 eV सर्व घटकांच्या आयनीकरण ऊर्जा (पहिली) ची तुलना करा →
- आयनीकरण ऊर्जा (दुसरी)
- 12.400043 eV सर्व घटकांच्या आयनीकरण ऊर्जा (दुसरी) ची तुलना करा →
- आयनीकरण ऊर्जा (तिसरी)
- 24.300084 eV सर्व घटकांच्या आयनीकरण ऊर्जा (तिसरी) ची तुलना करा →
- आयनीकरण ऊर्जा (चौथी)
- 40.000138 eV सर्व घटकांच्या आयनीकरण ऊर्जा (चौथी) ची तुलना करा →
- आयनीकरण ऊर्जा (पाचवी)
- 54.100186 eV सर्व घटकांच्या आयनीकरण ऊर्जा (पाचवी) ची तुलना करा →
- ऑक्सिडीकरण अवस्था
- +2, +3 सर्व घटकांच्या ऑक्सिडीकरण अवस्था ची तुलना करा →
- संयुजा इलेक्ट्रॉन
- 3 सर्व घटकांच्या संयुजा इलेक्ट्रॉन ची तुलना करा →
- इलेक्ट्रॉन संरूपण
- [Rn] 7s2 5f13
उष्मागतिक
- संप्लवन उष्मा
- 4.197544 eV
- अणूकरण उष्मा
- 4.197544 eV
केंद्रकीय
- प्रोटॉन
- 101 सर्व घटकांच्या प्रोटॉन ची तुलना करा →
- न्यूट्रॉन
- 157 सर्व घटकांच्या न्यूट्रॉन ची तुलना करा →
- ज्ञात समस्थानिके
- 19 सर्व घटकांच्या ज्ञात समस्थानिके ची तुलना करा →
- स्थिर समस्थानिके
- 0 सर्व घटकांच्या स्थिर समस्थानिके ची तुलना करा →
- वस्तुमानांक (सर्वाधिक स्थिर)
- 258
- सर्वाधिक स्थिर समस्थानिक
- Md-258
- शोधाचे वर्ष
- 1955
विपुलता
उपलब्ध नाही
स्फटिक संरचना
उपलब्ध नाही
इलेक्ट्रॉन संरचना
- प्रत्येक कवचातील इलेक्ट्रॉन
- 2, 8, 18, 32, 31, 8, 2 सर्व घटकांच्या प्रत्येक कवचातील इलेक्ट्रॉन ची तुलना करा →
ओळखचिन्हे
- CAS क्रमांक
- 7440-11-1 सर्व घटकांच्या CAS क्रमांक ची तुलना करा →
- टर्म चिन्ह
- 2F°7/2
- InChI
- InChI=1S/Md
- InChI की
- MQVSLOYRCXQRPM-UHFFFAOYSA-N
इलेक्ट्रॉन संरूपण मोजलेले
Md: 5f¹³ 7s²[Rn] 5f¹³ 7s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶ 5f¹³ 7s²अणुप्रतिमान
समस्थानिकांमुळे न्यूट्रॉन संख्या, वस्तुमान आणि स्थैर्य बदलते — विद्युतदृष्ट्या उदासीन अणूचे इलेक्ट्रॉन संरूपण बदलत नाही.
योजनात्मक अणुप्रतिमान, प्रमाणानुसार नाही.
अणूची विशिष्ट ओळख
उत्सर्जन / शोषण वर्णपट
समस्थानिक वितरण
स्थिर समस्थानिके नाहीत.
| वस्तुमानांक | अणुवस्तुमान (u) | नैसर्गिक विपुलता | अर्धायुष्य |
|---|---|---|---|
| 256 किरणोत्सारी | २५६.०९३८९ ± ०.०००१३ | उपलब्ध नाही | 77.7 मिनिटे |
| 250 किरणोत्सारी | २५०.०८४४१ ± ०.०००३२ | उपलब्ध नाही | 54 सेकंद |
| 258 किरणोत्सारी | २५८.०९८४३१५ ± ०.०००००५ | उपलब्ध नाही | 51.59 दिवस |
| 261 किरणोत्सारी | २६१.१०५८३ ± ०.०००६२ | उपलब्ध नाही | 40 मिनिटे |
| 260 किरणोत्सारी | २६०.१०३६५ ± ०.०००३४ | उपलब्ध नाही | 27.8 दिवस |
अवस्था / स्थिती
कारण: संप्लवनांकापेक्षा (826.85 °C) 801.9 °C कमी
योजनात्मक, प्रमाणानुसार नाही
अवस्थांतर बिंदू
अवस्थांतर ऊर्जा
संप्लवनांकावर 1 mol चे संप्लवन करण्यासाठी आवश्यक ऊर्जा
घनता
प्रमाणित परिस्थितीत
प्रमाणित परिस्थितीत
अणुवर्णपट
101 पैकी 10 दाखवले आहेत. आयनाच्या विद्युतभारानुसार चढत्या क्रमाने मांडलेले.
ऊर्जा पातळ्यांचा संग्रह ?
| आयन | विद्युतभार | पातळ्या |
|---|---|---|
| Md I | 0 | 2 |
| Md II | +1 | 2 |
| Md III | +2 | 2 |
| Md IV | +3 | 2 |
| Md V | +4 | 2 |
| Md VI | +5 | 2 |
| Md VII | +6 | 2 |
| Md VIII | +7 | 2 |
| Md IX | +8 | 2 |
| Md X | +9 | 2 |
स्फटिक संरचनेची माहिती उपलब्ध नाही
आयनिक त्रिज्या
| विद्युतभार | समन्वय | प्रचक्रण | त्रिज्या |
|---|---|---|---|
| +3 | 9 | उपलब्ध नाही | 109.5 pm |
संयुगे
समस्थानिके (5)
Fourteen isotopes are now recognized. 258Md has a half-life of 2 months. This isotope has been produced by the bombardment of an isotope of einsteinium with ions of helium. Eventually enough 258Md should be made to determine its physical properties.
| वस्तुमानांक | अणुवस्तुमान (u) | नैसर्गिक विपुलता | अर्धायुष्य | क्षय प्रकार | |
|---|---|---|---|---|---|
| 256 किरणोत्सारी | २५६.०९३८९ ± ०.०००१३ | उपलब्ध नाही | 77.7 मिनिटे | β+ =90.8±0.7%α =9.2±0.7%SF<3% | |
| 250 किरणोत्सारी | २५०.०८४४१ ± ०.०००३२ | उपलब्ध नाही | 54 सेकंद | β+ =93.0±0.8%α =7.0±0.8%β+SF =0.026±1.5% | |
| 258 किरणोत्सारी | २५८.०९८४३१५ ± ०.०००००५ | उपलब्ध नाही | 51.59 दिवस | α ≈100%β+<0.0015% β-<0.0015% | |
| 261 किरणोत्सारी | २६१.१०५८३ ± ०.०००६२ | उपलब्ध नाही | 40 मिनिटे | α ? | |
| 260 किरणोत्सारी | २६०.१०३६५ ± ०.०००३४ | उपलब्ध नाही | 27.8 दिवस | SF ≈100%α<5% ε<5% |
विस्तारित गुणधर्म
सहसंयुजी त्रिज्या (विस्तारित)
- सहसंयुजी त्रिज्या (प्युक्को)
- 173 pm
- सहसंयुजी त्रिज्या (प्युक्को, दुहेरी बंध)
- 139 pm
व्हॅन डर वाल्स त्रिज्या
- UFF
- 327.4 pm
क्रमांकन मापनपट्ट्या
- Mendeleev
- 38
- Pettifor
- 36
- Glawe
- 45
विद्युतऋणता मापनपट्ट्या
- Ghosh
- 0
ध्रुवणक्षमता आणि अपस्करण
- द्विध्रुव ध्रुवणक्षमता
- 109 a.u.
- द्विध्रुव ध्रुवणक्षमता (अनिश्चितता)
- 20 a.u.
अवस्थांतरे आणि अपरूपे
| द्रवणांक | 1100.15 K |
ऑक्सिडीकरण अवस्थांचे वर्ग
प्रगत संदर्भ माहिती
स्फटिक त्रिज्यांचा तपशील (1)
| विद्युतभार | CN | प्रचक्रण | rcrystal (pm) | उत्पत्ती |
|---|---|---|---|---|
| 3 | IX | — | 123.5 |
समस्थानिक क्षय प्रकार (45)
| समस्थानिक | मोड | तीव्रता |
|---|---|---|
| 244 | A | 100% |
| 244 | B+ | — |
| 244 | B+SF | 14% |
| 245 | A | 100% |
| 245 | B+ | — |
| 246 | A | 100% |
| 247 | A | 100% |
| 247 | SF | 0.1% |
| 248 | B+ | 80% |
| 248 | A | 20% |
अतिरिक्त माहिती
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
Not Applicable
संदर्भ (1)
- [5] Mendelevium https://education.jlab.org/itselemental/ele101.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
Not Applicable
संदर्भ (1)
- [5] Mendelevium https://education.jlab.org/itselemental/ele101.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 Mendelevium.
The element property data was retrieved from publications.