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Isotopes of mendelevium

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Isotopes of mendelevium (101Md)
Main isotopes[1] Decay
abun­dance half-life (t1/2) mode pro­duct
256Md synth 77.7 min ε 256Fm
α 252Es
257Md synth 5.52 h ε 257Fm
α 253Es
SF
258Md synth 51.5 d α 254Es
ε 258Fm
β 258No
259Md synth 1.60 h SF
α 255Es
260Md synth 31.8 d SF
α 256Es
ε 260Fm
β 260No

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

[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:
  1. ^ mMd – Excited nuclear isomer.
  2. ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. ^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. ^ Modes of decay:
    EC: Electron capture
    SF: Spontaneous fission
  5. ^ ( ) spin value – Indicates spin with weak assignment arguments.
  6. ^ a b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  7. ^ a b Discovery of this isotope is disputed due to conflicting data.[3]
  8. ^ a b c d e Order of ground state and isomer is uncertain.
  9. ^ 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]
  1. ^ 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.
  2. ^ 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.
  3. ^ 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.
  4. ^ 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.
  5. ^ see nobelium