Isotopes of mendelevium
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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 |
Daughter isotope |
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Excitation energy[n 6] | |||||||||||||||||||
244Md[2] | 101 | 143 | 0.30+0.19 −0.09 s |
α | 240Es | ||||||||||||||
245Md[2] | 101 | 144 | 245.08081(33)# | 0.33+0.15 −0.08 s |
α | 241Es | 7/2−# | ||||||||||||
β+ (rare) | 245Fm | ||||||||||||||||||
245mMd | 200(100)# keV | 0.90(25) ms | SF | (various) | 1/2−# | ||||||||||||||
246Md[3] | 101 | 145 | 246.08171(28)# | 0.9(2) s | α | 242Es | |||||||||||||
β+? | 246Fm | ||||||||||||||||||
246mMd | 4.4(8) s | β+ (>67%) | 246Fm | ||||||||||||||||
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) | ||||||||||||||||||
β+? | 247Fm | ||||||||||||||||||
247mMd | 153 keV | 0.23(3) s | α (80%) | 243Es | (1/2−) | ||||||||||||||
SF (20%) | (various) | ||||||||||||||||||
248Md | 101 | 147 | 248.08282(26)# | 7(3) s | β+ (80%) | 248Fm | |||||||||||||
α (20%) | 244Es | ||||||||||||||||||
β+, SF (.05%) | (various) | ||||||||||||||||||
249Md[5] | 101 | 148 | 249.08291(22)# | 26(1) s | α (75%) | 245Es | (7/2−) | ||||||||||||
β+ (25%) | 249Fm | ||||||||||||||||||
249mMd[6] | 100(100)# keV | 1.5+1.2 −0.5 s |
α | 245Es | (1/2−) | ||||||||||||||
250Md[7] | 101 | 149 | 250.08442(32)# | 54(4) s | β+ (93.0%) | 250Fm | |||||||||||||
α (7.0%) | 246Es | ||||||||||||||||||
β+, SF (0.026%) | (various) | ||||||||||||||||||
251Md[8] | 101 | 150 | 251.084774(20) | 4.27(26) min | β+ (90%) | 251Fm | (7/2−) | ||||||||||||
α (10%) | 247Es | ||||||||||||||||||
252Md | 101 | 151 | 252.08643(14)# | 2.3(8) min | β+ | 252Fm | |||||||||||||
α (rare)[9] | 248Es | ||||||||||||||||||
253Md | 101 | 152 | 253.08714(3)# | 12(8) min [6.4+11.6 −3.6 min] |
β+ (~99%)[10] | 253Fm | (7/2−) | ||||||||||||
α (~1%) | 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 (rare) | (various) | ||||||||||||||||||
258Md[11] | 101 | 157 | 258.098431(5) | 51.59(29) d | α | 254Es | (8−)# | ||||||||||||
β− (<0.0015%) | 258No | ||||||||||||||||||
β+ (<0.0015%) | 258Fm | ||||||||||||||||||
258mMd | 0(200)# keV | 57.0(9) min | EC | 258Fm | 1−# | ||||||||||||||
SF (<15%) | (various) | ||||||||||||||||||
α (<1.2%) | 254Es | ||||||||||||||||||
β− (rare) | 258No | ||||||||||||||||||
259Md[n 7][12] | 101 | 158 | 259.10051(22)# | 1.60(6) h | SF | (various) | 7/2−# | ||||||||||||
α (rare) | 255Es | ||||||||||||||||||
260Md[13] | 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).
- ^ 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)[14] |
260Md | 1989 | 254Es+18O, 22Ne — transfer |
References
- 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. S2CID 250839471.
- Audi, Georges; Bersillon, Olivier; Blachot, Jean;
- 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.
- Half-life, spin, and isomer data selected from the following sources.
- Audi, Georges; Bersillon, Olivier; Blachot, Jean;
- 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.). 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. S2CID 94982856.