Isotopes of mendelevium
(Redirected from Mendelevium-256)
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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.
List of isotopes
Nuclide [n 1] |
Z | N | Isotopic mass (Da) [n 2][n 3] |
Half-life |
Decay mode [n 4] |
Daughter isotope |
Spin and parity [n 5][n 6] | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Excitation energy[n 6] | |||||||||||||||||||
244Md[1] | 101 | 143 | 0.36(0.14) s | α | 240Es | ||||||||||||||
245Md | 101 | 144 | 245.08081(33)# | 0.90(25) ms | SF | (various) | (1/2−)# | ||||||||||||
α (rare) | 241Es | ||||||||||||||||||
245mMd | 200(100)# keV | 400(200) ms [0.35(+23−16) s] |
α | 241Es | (7/2+) | ||||||||||||||
β+ (rare) | 245Fm | ||||||||||||||||||
246Md | 101 | 145 | 246.08171(28)# | 1.0(4) s | α | 242Es | |||||||||||||
β+ (rare) | 246Fm | ||||||||||||||||||
247Md | 101 | 146 | 247.08152(22)# | 1.12(22) s | SF | (various) | 1/2−# | ||||||||||||
α (rare) | 243Es | ||||||||||||||||||
247mMd | ~0.2 s | α (99.99%) | 243Es | ||||||||||||||||
SF (10−4%) | (various) | ||||||||||||||||||
248Md | 101 | 147 | 248.08282(26)# | 7(3) s | β+ (80%) | 248Fm | |||||||||||||
α (20%) | 244Es | ||||||||||||||||||
β+, SF (.05%) | (various) | ||||||||||||||||||
249Md | 101 | 148 | 249.08291(22)# | 24(4) s | α (60%) | 245Es | (7/2−) | ||||||||||||
β+ (40%) | 249Fm | ||||||||||||||||||
249mMd | 100(100)# keV | 1.9(9) s | (1/2−) | ||||||||||||||||
250Md | 101 | 149 | 250.08442(32)# | 52(6) s | β+ (93%) | 250Fm | |||||||||||||
α (7%) | 246Es | ||||||||||||||||||
β+, SF (.02%) | (various) | ||||||||||||||||||
251Md | 101 | 150 | 251.084774(20) | 4.0(5) min | β+ (90%) | 251Fm | 7/2−# | ||||||||||||
α (10%) | 247Es | ||||||||||||||||||
252Md | 101 | 151 | 252.08643(14)# | 2.3(8) min | β+ (50%) | 252Fm | |||||||||||||
α (50%) | 248Es | ||||||||||||||||||
253Md | 101 | 152 | 253.08714(3)# | 12(8) min [6(+12−3) min] |
β+ | 253Fm | 7/2−# | ||||||||||||
α | 249Es | ||||||||||||||||||
254Md | 101 | 153 | 254.08959(11)# | 10(3) min | β+ | 254Fm | (0−) | ||||||||||||
α (rare) | 250Es | ||||||||||||||||||
254mMd | 50(100)# keV | 28(8) min | β+ | 254Fm | (3−) | ||||||||||||||
α (rare) | 250Es | ||||||||||||||||||
255Md | 101 | 154 | 255.091084(7) | 27(2) min | β+ (92%) | 255Fm | (7/2−) | ||||||||||||
α (8%) | 251Es | ||||||||||||||||||
SF (.15%) | (various) | ||||||||||||||||||
256Md | 101 | 155 | 256.09389(13)# | 77(2) min | β+ (89%) | 256Fm | (1−) | ||||||||||||
α (11%) | 252Es | ||||||||||||||||||
257Md | 101 | 156 | 257.0955424(29) | 5.52(5) h | EC (84.8%) | 257Fm | (7/2−) | ||||||||||||
α (15.2%) | 253Es | ||||||||||||||||||
SF (1%) | (various) | ||||||||||||||||||
258Md | 101 | 157 | 258.098431(5) | 51.5(3) d | α (99.99%) | 254Es | (8−)# | ||||||||||||
β− (.0015%) | 258No | ||||||||||||||||||
β+ (.0015%) | 258Fm | ||||||||||||||||||
258mMd | 0(200)# keV | 57.0(9) min | EC (70%) | 258Fm | 1−# | ||||||||||||||
SF (20%) | (various) | ||||||||||||||||||
β− (10%) | 258No | ||||||||||||||||||
α (1.2%) | 254Es | ||||||||||||||||||
259Md[n 7] | 101 | 158 | 259.10051(22)# | 1.60(6) h | SF (98.7%) | (various) | 7/2−# | ||||||||||||
α (1.3%) | 255Es | ||||||||||||||||||
260Md | 101 | 159 | 260.10365(34)# | 27.8(8) d | SF (85%) | (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).
- ^ Not directly synthesized, occurs as decay product of 259No
Chronology of isotope discovery
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)[2] |
260Md | 1989 | 254Es+18O, 22Ne — transfer |
References
- ^ Pore, J. L.; Gates, J. M.; Orford, R.; Campbell, C. M.; Clark, R. M.; Crawford, H. L.; Esker, N. E.; Fallon, P.; Gooding, J. A.; Kwarsick, J. T.; Macchiavelli, A. O.; Morse, C.; Rudolph, D.; Såmark-Roth, A.; Santamaria, C.; Shah, R. S.; Stoyer, M. A. (2020). "Identification of the new isotope 244Md" (PDF). Physical Review Letters. 124 (25–26). doi:10.1103/PhysRevLett.124.252502.
- ^ 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.
- 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
- Isotopic compositions and standard atomic masses from:
- de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
- Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051.
- "News & Notices: Standard Atomic Weights Revised". International Union of Pure and Applied Chemistry. 19 October 2005.
- 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.