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
257Mdsynth5.52 hε 257Fm
α 253Es
SF –
258Mdsynth51.5 dα 254Es
ε 258Fm
β− 258No
259Mdsynth1.60 hSF–
α 255Es
260Mdsynth31.8 dSF–
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.

Contents

List of isotopes


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] 101143244.08116(40)#0.36(14) s α 240Es3+#
β+, SF (<14%)(various)
244mMd [n 7] 200(150)# keV~9 μsIT244Md7+#
245Md101144245.08086(28)#0.38(10) sα241Es(7/2−)
245mMd [n 8] 100(100)# keV0.90(25) msSF(various)1/2−#
246Md101145246.08171(28)#0.92(18) sα242Es1−#
246mMd [n 8] 60(60) keV4.4(8) sβ+ (~67%)246Fm4−#
α (<23%)242Es
β+, SF (>10%)(various)
247Md [4] 101146247.08152(22)#1.20(12) sα (99.14%)243Es(7/2−)
SF (0.86%)(various)
247mMd153 keV0.23(3) sα (80%)243Es(1/2−)
SF (20%)(various)
248Md101147248.08261(20)#7(3) sβ+ (80%)248Fm
α (20%)244Es
β+, SF (<0.05%)(various)
249Md101148249.08286(18)25.6(9) sα (75%)245Es(7/2−)
β+ (25%)249Fm
249mMd [n 8] 100(100)# keV1.9(9) sα245Es(1/2−)
250Md101149250.084165(98)54(4) sβ+ (93.0%)250Fm2−#
α (7.0%)246Es
β+, SF (0.026%)(various)
250mMd120(40) keV42.4(45) sα246Es7+#
251Md101150251.084774(20)4.21(23) minβ+ (90%)251Fm(7/2−)
α (10%)247Es
251mMd53(8) keV20# s(1/2−)
252Md101151252.086385(98)2.3(8) minβ+252Fm1+#
253Md101152253.087143(34)#12(8) minβ+ (~99.3%)253Fm(7/2−)
α (~0.7%)249Es
253mMd60(30) keV1# min(1/2−)
254Md101153254.08959(11)#10(3) minβ+254Fm0−#
254mMd [n 8] 50(100)# keV28(8) minβ+254Fm3−#
255Md101154255.0910817(60)27(2) minβ+ (93%)255Fm7/2−
α (7%)251Es
256Md101155256.09389(13)#77.7(18) minβ+ (90.8%)256Fm(1−)
α (9.2%)252Es
SF (<3%)(various)
257Md101156257.0955373(17)5.52(5) h EC (85%)257Fm(7/2−)
α (15%)253Es
258Md101157258.0984336(37)51.59(29) dα254Es(8−)#
β− (<0.0015%)258No
β+ (<0.0015%)258Fm
258mMd [n 8] 0(200)# keV57.0(9) minEC (85%)258Fm1−#
SF (<15%)(various)
α (<1.2%)254Es
259Md [n 9] 101158259.10045(11)#1.60(6) hSF(various)7/2−#
260Md101159260.10365(34)#27.8(8) dSF(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. 1 2 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  7. 1 2 Discovery of this isotope is disputed due to conflicting data. [3]
  8. 1 2 3 4 5 Order of ground state and isomer is uncertain.
  9. ↑ Not directly synthesized, occurs as decay product of 259No

Chronology of isotope discovery

IsotopeDiscoveredReaction
244Md2020209Bi(40Ar,5n)
245Md1996209Bi(40Ar,4n)
246Md1996209Bi(40Ar,3n)
247Md1981209Bi(40Ar,2n)
248Md1973241Am(12C,5n)
249Md1973241Am(12C,4n)
250Md1973243Am(12C,5n), 243Am(13C,6n)
251Md1973243Am(12C,4n), 243Am(13C,5n)
252Md1973243Am(13C,4n)
253Md1992243Am(13C,3n)
254Md1970253Es(α,3n)
255Md1958253Es(α,2n)
256Md1955253Es(α,n)
257Md1964252Cf(11B,α2n)
258Md1970255Es(α,n)
259Md1982248Cm(18O,α3n) [5]
260Md1989254Es+18O, 22Ne — transfer

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References

  1. 1 2 3 4 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). 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
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