Mendelevium (101Md) is a synthetic element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 256Md (which was also the first isotope of any element produced one atom at a time) in 1955. There are 17 known radioisotopes, ranging in atomic mass from 244Md to 260Md, and 5 isomers. The longest-lived isotope is 258Md with a half-life of 51.3 days, and the longest-lived isomer is 258mMd with a half-life of 57 minutes.
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List of isotopes
edit
| Nuclide [n 1] |
Z | N | Isotopic mass (Da)[2] [n 2][n 3] |
Half-life[1] |
Decay mode[1] [n 4] |
Daughter isotope |
Spin and parity[1] [n 5][n 6] | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Excitation energy[n 6] | |||||||||||||||||||
| 244Md[n 7] | 101 | 143 | 244.08116(40)# | 0.36(14) s | α | 240Es | 3+# | ||||||||||||
| β+, SF (<14%) | (various) | ||||||||||||||||||
| 244mMd[n 7] | 200(150)# keV | ~9 μs | IT | 244Md | 7+# | ||||||||||||||
| 245Md | 101 | 144 | 245.08086(28)# | 0.38(10) s | α | 241Es | (7/2−) | ||||||||||||
| 245mMd[n 8] | 100(100)# keV | 0.90(25) ms | SF | (various) | 1/2−# | ||||||||||||||
| 246Md | 101 | 145 | 246.08171(28)# | 0.92(18) s | α | 242Es | 1−# | ||||||||||||
| 246mMd[n 8] | 60(60) keV | 4.4(8) s | β+ (~67%) | 246Fm | 4−# | ||||||||||||||
| α (<23%) | 242Es | ||||||||||||||||||
| β+, SF (>10%) | (various) | ||||||||||||||||||
| 247Md[4] | 101 | 146 | 247.08152(22)# | 1.20(12) s | α (99.14%) | 243Es | (7/2−) | ||||||||||||
| SF (0.86%) | (various) | ||||||||||||||||||
| 247mMd | 153 keV | 0.23(3) s | α (80%) | 243Es | (1/2−) | ||||||||||||||
| SF (20%) | (various) | ||||||||||||||||||
| 248Md | 101 | 147 | 248.08261(20)# | 7(3) s | β+ (80%) | 248Fm | |||||||||||||
| α (20%) | 244Es | ||||||||||||||||||
| β+, SF (<0.05%) | (various) | ||||||||||||||||||
| 249Md | 101 | 148 | 249.08286(18) | 25.6(9) s | α (75%) | 245Es | (7/2−) | ||||||||||||
| β+ (25%) | 249Fm | ||||||||||||||||||
| 249mMd[n 8] | 100(100)# keV | 1.9(9) s | α | 245Es | (1/2−) | ||||||||||||||
| 250Md | 101 | 149 | 250.084165(98) | 54(4) s | β+ (93.0%) | 250Fm | 2−# | ||||||||||||
| α (7.0%) | 246Es | ||||||||||||||||||
| β+, SF (0.026%) | (various) | ||||||||||||||||||
| 250mMd | 120(40) keV | 42.4(45) s | α | 246Es | 7+# | ||||||||||||||
| 251Md | 101 | 150 | 251.084774(20) | 4.21(23) min | β+ (90%) | 251Fm | (7/2−) | ||||||||||||
| α (10%) | 247Es | ||||||||||||||||||
| 251mMd | 53(8) keV | 20# s | (1/2−) | ||||||||||||||||
| 252Md | 101 | 151 | 252.086385(98) | 2.3(8) min | β+ | 252Fm | 1+# | ||||||||||||
| 253Md | 101 | 152 | 253.087143(34)# | 12(8) min | β+ (~99.3%) | 253Fm | (7/2−) | ||||||||||||
| α (~0.7%) | 249Es | ||||||||||||||||||
| 253mMd | 60(30) keV | 1# min | (1/2−) | ||||||||||||||||
| 254Md | 101 | 153 | 254.08959(11)# | 10(3) min | β+ | 254Fm | 0−# | ||||||||||||
| 254mMd[n 8] | 50(100)# keV | 28(8) min | β+ | 254Fm | 3−# | ||||||||||||||
| 255Md | 101 | 154 | 255.0910817(60) | 27(2) min | β+ (93%) | 255Fm | 7/2− | ||||||||||||
| α (7%) | 251Es | ||||||||||||||||||
| 256Md | 101 | 155 | 256.09389(13)# | 77.7(18) min | β+ (90.8%) | 256Fm | (1−) | ||||||||||||
| α (9.2%) | 252Es | ||||||||||||||||||
| SF (<3%) | (various) | ||||||||||||||||||
| 257Md | 101 | 156 | 257.0955373(17) | 5.52(5) h | EC (85%) | 257Fm | (7/2−) | ||||||||||||
| α (15%) | 253Es | ||||||||||||||||||
| 258Md | 101 | 157 | 258.0984336(37) | 51.59(29) d | α | 254Es | (8−)# | ||||||||||||
| β− (<0.0015%) | 258No | ||||||||||||||||||
| β+ (<0.0015%) | 258Fm | ||||||||||||||||||
| 258mMd[n 8] | 0(200)# keV | 57.0(9) min | EC (85%) | 258Fm | 1−# | ||||||||||||||
| SF (<15%) | (various) | ||||||||||||||||||
| α (<1.2%) | 254Es | ||||||||||||||||||
| 259Md[n 9] | 101 | 158 | 259.10045(11)# | 1.60(6) h | SF | (various) | 7/2−# | ||||||||||||
| 260Md | 101 | 159 | 260.10365(34)# | 27.8(8) d | SF | (various) | |||||||||||||
| α (<5%) | 256Es | ||||||||||||||||||
| EC (<5%) | 260Fm | ||||||||||||||||||
| β− (<3.5%) | 260No | ||||||||||||||||||
| This table header & footer: | |||||||||||||||||||
- ^ mMd – Excited nuclear isomer.
- ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
- ^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
- ^
Modes of decay:
EC: Electron capture SF: Spontaneous fission - ^ ( ) spin value – Indicates spin with weak assignment arguments.
- ^ a b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
- ^ a b Discovery of this isotope is disputed due to conflicting data.[3]
- ^ a b c d e Order of ground state and isomer is uncertain.
- ^ Not directly synthesized, occurs as decay product of 259No
Chronology of isotope discovery
edit| Isotope | Discovered | Reaction |
|---|---|---|
| 244Md | 2020 | 209Bi(40Ar,5n) |
| 245Md | 1996 | 209Bi(40Ar,4n) |
| 246Md | 1996 | 209Bi(40Ar,3n) |
| 247Md | 1981 | 209Bi(40Ar,2n) |
| 248Md | 1973 | 241Am(12C,5n) |
| 249Md | 1973 | 241Am(12C,4n) |
| 250Md | 1973 | 243Am(12C,5n), 243Am(13C,6n) |
| 251Md | 1973 | 243Am(12C,4n), 243Am(13C,5n) |
| 252Md | 1973 | 243Am(13C,4n) |
| 253Md | 1992 | 243Am(13C,3n) |
| 254Md | 1970 | 253Es(α,3n) |
| 255Md | 1958 | 253Es(α,2n) |
| 256Md | 1955 | 253Es(α,n) |
| 257Md | 1964 | 252Cf(11B,α2n) |
| 258Md | 1970 | 255Es(α,n) |
| 259Md | 1982 | 248Cm(18O,α3n)[5] |
| 260Md | 1989 | 254Es+18O, 22Ne — transfer |
References
edit- ^ a b c d Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
- ^ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
- ^ Heßberger, F. P.; Block, M.; Düllmann, Ch. E.; Yakushev, A.; Leino, M.; Uusitalo, J. (3 May 2021). "Some Remarks on the Discovery of Md 244". Physical Review Letters. 126 (18). arXiv:2101.06076. doi:10.1103/PhysRevLett.126.182501.
- ^ Heßberger, F. P.; Antalic, S.; Giacoppo, F.; Andel, B.; Ackermann, D.; Block, M.; Heinz, S.; Khuyagbaatar, J.; Kojouharov, I.; Venhart, M. (25 January 2022). "Alpha-gamma decay studies of 247Md". The European Physical Journal A. 58 (1): 11. Bibcode:2022EPJA...58...11H. doi:10.1140/epja/s10050-022-00663-4. ISSN 1434-601X. S2CID 246281669.
- ^ see nobelium
- Isotope masses from:
- M. Wang; G. Audi; A. H. Wapstra; F. G. Kondev; M. MacCormick; X. Xu; et al. (2012). "The AME2012 atomic mass evaluation (II). Tables, graphs and references" (PDF). Chinese Physics C. 36 (12): 1603–2014. Bibcode:2012ChPhC..36....3M. doi:10.1088/1674-1137/36/12/003. S2CID 250839471.
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
- Half-life, spin, and isomer data selected from the following sources.
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
- National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
- Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.
- M. Thoennessen (2012). "Discovery of Isotopes of Elements with Z≥100". Atomic Data and Nuclear Data Tables. 99 (3): 312–344. arXiv:1203.2105. Bibcode:2013ADNDT..99..312T. doi:10.1016/j.adt.2012.03.003. S2CID 94982856.