Mendelevium (Md)
actinideSolid
표준 원자량
[258]전자 배치
[Rn] 7s2 5f13녹는점
826.85 °C끓는점
해당 없음밀도
1.03e+4 kg/m³산화 상태
+2, +3전기 음성도(Pauling)
1.3제1 이온화 에너지
6.58 eV발견 연도
1955원자 반지름
해당 없음상세 정보
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.
이미지
특성
물리적 특성
- 반데르발스 반지름
- 246 pm 모든 원소의 반데르발스 반지름 비교 →
- 밀도
- 1.03 × 104 kg/m³ 모든 원소의 밀도 비교 →
- STP에서의 상
- 고체 모든 원소의 STP에서의 상 비교 →
- 녹는점
- 826.85 °C 모든 원소의 녹는점 비교 →
화학적 특성
- 전기 음성도(Pauling)
- 1.3 모든 원소의 전기 음성도(Pauling) 비교 →
- 전자 친화도
- 0.997 eV
- 제1 이온화 에너지
- 6.58 eV 모든 원소의 제1 이온화 에너지 비교 →
- 제2 이온화 에너지
- 12.400043 eV 모든 원소의 제2 이온화 에너지 비교 →
- 제3 이온화 에너지
- 24.300084 eV 모든 원소의 제3 이온화 에너지 비교 →
- 제4 이온화 에너지
- 40.000138 eV 모든 원소의 제4 이온화 에너지 비교 →
- 제5 이온화 에너지
- 54.100186 eV 모든 원소의 제5 이온화 에너지 비교 →
- 산화 상태
- +2, +3 모든 원소의 산화 상태 비교 →
- 원자가 전자
- 3 모든 원소의 원자가 전자 비교 →
- 전자 배치
- [Rn] 7s2 5f13
열역학적 특성
- 승화열
- 4.197544 eV
- 원자화열
- 4.197544 eV
핵 특성
- 양성자 수
- 101 모든 원소의 양성자 수 비교 →
- 중성자 수
- 157 모든 원소의 중성자 수 비교 →
- 알려진 동위원소 수
- 19 모든 원소의 알려진 동위원소 수 비교 →
- 안정 동위원소 수
- 0 모든 원소의 안정 동위원소 수 비교 →
- 질량수(가장 안정한 동위원소)
- 258
- 가장 안정한 동위원소
- Md-258
- 발견 연도
- 1955
존재비
해당 없음
결정 구조
해당 없음
전자 구조
- 전자껍질별 전자 수
- 2, 8, 18, 32, 31, 8, 2 모든 원소의 전자껍질별 전자 수 비교 →
식별자
- CAS 등록 번호
- 7440-11-1 모든 원소의 CAS 등록 번호 비교 →
- 항 기호
- 2F°7/2
- InChI
- InChI=1S/Md
- InChI 키
- MQVSLOYRCXQRPM-UHFFFAOYSA-N
전자 배치 측정값
Md: 5f¹³ 7s²[Rn] 5f¹³ 7s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶ 5f¹³ 7s²원자 모형
동위원소에 따라 중성자 수, 질량, 안정성은 달라지지만, 중성 원자의 전자 배치는 달라지지 않습니다.
개략적인 원자 모형이며 실제 비율과 다릅니다.
원자 지문
방출 / 흡수 스펙트럼
동위원소 분포
안정 동위원소가 없습니다.
| 질량수 | 원자 질량(u) | 천연 존재비 | 반감기 |
|---|---|---|---|
| 256 방사성 | 256.09389 ± 0.00013 | 해당 없음 | 77.7 분 |
| 250 방사성 | 250.08441 ± 0.00032 | 해당 없음 | 54 초 |
| 258 방사성 | 258.0984315 ± 0.000005 | 해당 없음 | 51.59 일 |
| 261 방사성 | 261.10583 ± 0.00062 | 해당 없음 | 40 분 |
| 260 방사성 | 260.10365 ± 0.00034 | 해당 없음 | 27.8 일 |
상 / 상태
이유: 승화점(826.85 °C)보다 801.9 °C 낮음
개략도이며 실제 비율과 다름
상전이점
전이 에너지
승화점에서 1 mol을 승화시키는 데 필요한 에너지
밀도
표준 조건에서
표준 조건에서
원자 스펙트럼
전체 101개 중 10개를 표시합니다. 이온 전하순으로 정렬되었습니다(오름차순).
보유 에너지 준위 데이터 ?
| 이온 | 전하 | 준위 |
|---|---|---|
| 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 |
결정 구조 데이터 없음
이온 반지름
| 전하 | 배위 | 스핀 | 반지름 |
|---|---|---|---|
| +3 | 9 | 해당 없음 | 109.5 pm |
화합물
동위원소 (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.
| 질량수 | 원자 질량(u) | 천연 존재비 | 반감기 | 붕괴 방식 | |
|---|---|---|---|---|---|
| 256 방사성 | 256.09389 ± 0.00013 | 해당 없음 | 77.7 분 | β+ =90.8±0.7%α =9.2±0.7%SF<3% | |
| 250 방사성 | 250.08441 ± 0.00032 | 해당 없음 | 54 초 | β+ =93.0±0.8%α =7.0±0.8%β+SF =0.026±1.5% | |
| 258 방사성 | 258.0984315 ± 0.000005 | 해당 없음 | 51.59 일 | α ≈100%β+<0.0015% β-<0.0015% | |
| 261 방사성 | 261.10583 ± 0.00062 | 해당 없음 | 40 분 | α ? | |
| 260 방사성 | 260.10365 ± 0.00034 | 해당 없음 | 27.8 일 | SF ≈100%α<5% ε<5% |
확장 특성
공유 결합 반지름(확장)
- 공유 결합 반지름(Pyykkö)
- 173 pm
- 공유 결합 반지름(Pyykkö, 이중 결합)
- 139 pm
반데르발스 반지름
- UFF
- 327.4 pm
번호 척도
- Mendeleev
- 38
- Pettifor
- 36
- Glawe
- 45
전기 음성도 척도
- Ghosh
- 0
분극률 및 분산
- 쌍극자 분극률
- 109 a.u.
- 쌍극자 분극률(불확도)
- 20 a.u.
상전이 및 동소체
| 녹는점 | 1100.15 K |
산화 상태 분류
심화 참고 데이터
결정 반지름 상세 정보 (1)
| 전하 | CN | 스핀 | rcrystal (pm) | 기원 |
|---|---|---|---|---|
| 3 | IX | — | 123.5 |
동위원소 붕괴 방식 (45)
| 동위원소 | 모드 | 세기 |
|---|---|---|
| 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% |
추가 데이터
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
Not Applicable
참고 문헌 (1)
- [5] Mendelevium https://education.jlab.org/itselemental/ele101.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
Not Applicable
참고 문헌 (1)
- [5] Mendelevium https://education.jlab.org/itselemental/ele101.html
참고 문헌
(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.