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Isotopes of mendelevium

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Isotopes of mendelevium (101Md)
Main isotopes Decay
abun­dance half-life (t1/2) mode pro­duct
Md synth 77.7 min ε Fm
α Es
Md synth 5.52 h ε Fm
α Es
SF
Md synth 51.5 d α Es
ε Fm
β No
Md synth 1.60 h SF
α Es
Md synth 31.8 d SF
α Es
ε Fm
β No

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 Md (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 Md to Md, and 5 isomers. The longest-lived isotope is Md with a half-life of 51.3 days, and the longest-lived isomer is Md with a half-life of 57 minutes.

List of isotopes


Nuclide
Z N Isotopic mass (Da)
Half-life
Decay
mode

Daughter
isotope

Spin and
parity
Excitation energy
Md 101 143 244.08116(40)# 0.36(14) s α Es 3+#
β, SF (<14%) (various)
Md 200(150)# keV ~9 μs IT Md 7+#
Md 101 144 245.08086(28)# 0.38(10) s α Es (7/2−)
Md 100(100)# keV 0.90(25) ms SF (various) 1/2−#
Md 101 145 246.08171(28)# 0.92(18) s α Es 1−#
Md 60(60) keV 4.4(8) s β (~67%) Fm 4−#
α (<23%) Es
β, SF (>10%) (various)
Md 101 146 247.08152(22)# 1.20(12) s α (99.14%) Es (7/2−)
SF (0.86%) (various)
Md 153 keV 0.23(3) s α (80%) Es (1/2−)
SF (20%) (various)
Md 101 147 248.08261(20)# 7(3) s β (80%) Fm
α (20%) Es
β, SF (<0.05%) (various)
Md 101 148 249.08286(18) 25.6(9) s α (75%) Es (7/2−)
β (25%) Fm
Md 100(100)# keV 1.9(9) s α Es (1/2−)
Md 101 149 250.084165(98) 54(4) s β (93.0%) Fm 2−#
α (7.0%) Es
β, SF (0.026%) (various)
Md 120(40) keV 42.4(45) s α Es 7+#
Md 101 150 251.084774(20) 4.21(23) min β (90%) Fm (7/2−)
α (10%) Es
Md 53(8) keV 20# s (1/2−)
Md 101 151 252.086385(98) 2.3(8) min β Fm 1+#
Md 101 152 253.087143(34)# 12(8) min β (~99.3%) Fm (7/2−)
α (~0.7%) Es
Md 60(30) keV 1# min (1/2−)
Md 101 153 254.08959(11)# 10(3) min β Fm 0−#
Md 50(100)# keV 28(8) min β Fm 3−#
Md 101 154 255.0910817(60) 27(2) min β (93%) Fm 7/2−
α (7%) Es
Md 101 155 256.09389(13)# 77.7(18) min β (90.8%) Fm (1−)
α (9.2%) Es
SF (<3%) (various)
Md 101 156 257.0955373(17) 5.52(5) h EC (85%) Fm (7/2−)
α (15%) Es
Md 101 157 258.0984336(37) 51.59(29) d α Es (8−)#
β (<0.0015%) No
β (<0.0015%) Fm
Md 0(200)# keV 57.0(9) min EC (85%) Fm 1−#
SF (<15%) (various)
α (<1.2%) Es
Md 101 158 259.10045(11)# 1.60(6) h SF (various) 7/2−#
Md 101 159 260.10365(34)# 27.8(8) d SF (various)
α (<5%) Es
EC (<5%) Fm
β (<3.5%) No
This table header & footer:
  1. Md – 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. ^ # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  7. ^ Discovery of this isotope is disputed due to conflicting data.
  8. ^ Order of ground state and isomer is uncertain.
  9. Not directly synthesized, occurs as decay product of No

Chronology of isotope discovery

Isotope Discovered Reaction
Md 2020 Bi(Ar,5n)
Md 1996 Bi(Ar,4n)
Md 1996 Bi(Ar,3n)
Md 1981 Bi(Ar,2n)
Md 1973 Am(C,5n)
Md 1973 Am(C,4n)
Md 1973 Am(C,5n), Am(C,6n)
Md 1973 Am(C,4n), Am(C,5n)
Md 1973 Am(C,4n)
Md 1992 Am(C,3n)
Md 1970 Es(α,3n)
Md 1958 Es(α,2n)
Md 1955 Es(α,n)
Md 1964 Cf(B,α2n)
Md 1970 Es(α,n)
Md 1982 Cm(O,α3n)
Md 1989 Es+O, Ne — transfer

References

  1. ^ 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 Md". 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
Isotopes of the chemical elements
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Period Hydrogen and
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