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.
Quick Facts Main isotopes, Decay ...
Close
More information Nuclide, Z ...
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[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[n 7] |
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[n 7] |
60(60) keV |
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][n 7] |
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[n 7] |
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[n 7] |
0(200)# keV |
57.0(9) min |
EC |
258Fm |
1−# |
SF (<15%) |
(various) |
α (<1.2%) |
254Es |
β− (rare) |
258No |
259Md[n 8][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: |
Close
( ) – 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).
( ) spin value – Indicates spin with weak assignment arguments.
# – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
Order of ground state and isomer is uncertain.
Not directly synthesized, occurs as decay product of 259No
More information Isotope, Discovered ...
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 |
Close
Khuyagbaatar, J.; Albers, H. M.; Block, M.; Brand, H.; Cantemir, R. A.; Di Nitto, A.; Düllmann, Ch. E.; Götz, M.; Götz, S.; Heßberger, F. P.; Jäger, E.; Kindler, B.; Kratz, J. V.; Krier, J.; Kurz, N.; Lommel, B.; Lens, L.; Mistry, A.; Schausten, B.; Uusitalo, J.; Yakushev, A. (1 October 2020). "Search for Electron-Capture Delayed Fission in the New Isotope 244Md". Physical Review Letters. 125 (14): 142504. Bibcode:2020PhRvL.125n2504K. doi:10.1103/PhysRevLett.125.142504. PMID 33064498. S2CID 223546973. Antalic, S.; Heßberger, F. P.; Hofmann, S.; Ackermann, D.; Heinz, S.; Kindler, B.; Kojouharov, I.; Kuusiniemi, P.; Leino, M.; Lommel, B.; Mann, R.; Šáro, Š. (20 November 2009). "Studies of neutron-deficient mendelevium isotopes at SHIP". The European Physical Journal A. 43 (1): 35. doi:10.1140/epja/i2009-10896-0. ISSN 1434-601X. S2CID 121963345. 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. Briselet, R.; Theisen, Ch.; Vandebrouck, M.; Marchix, A.; Airiau, M.; Auranen, K.; Badran, H.; Boilley, D.; Calverley, T.; Cox, D.; Déchery, F.; Defranchi Bisso, F.; Drouart, A.; Gall, B.; Goigoux, T.; Grahn, T.; Greenlees, P. T.; Hauschild, K.; Herzan, A.; Herzberg, R. D.; Jakobsson, U.; Julin, R.; Juutinen, S.; Konki, J.; Leino, M.; Lightfoot, A.; Lopez-Martens, A.; Mistry, A.; Nieminen, P.; Pakarinen, J.; Papadakis, P.; Partanen, J.; Peura, P.; Rahkila, P.; Rubert, J.; Ruotsalainen, P.; Sandzelius, M.; Saren, J.; Scholey, C.; Sorri, J.; Stolze, S.; Sulignano, B.; Uusitalo, J.; Ward, A.; Zielińska, M. (14 February 2019). "Production cross section and decay study of $^{243}\mathrm{Es}$ and $^{249}\mathrm{Md}$". Physical Review C. 99 (2): 024614. arXiv:1809.10400. doi:10.1103/PhysRevC.99.024614. S2CID 119533032. Heßberger, F.P.; Hofmann, S.; Ackermann, D.; Ninov, V.; Leino, M.; Münzenberg, G.; Saro, S.; Lavrentev, A.; Popeko, A.G.; Yeremin, A.V.; Stodel, Ch. (1 September 2001). "Decay properties of neutron-deficient isotopes 256, 257Db, 255Rf, 252, 253Lr". The European Physical Journal A - Hadrons and Nuclei. 12 (1): 57–67. Bibcode:2001EPJA...12...57H. doi:10.1007/s100500170039. ISSN 1434-601X. S2CID 117896888. Retrieved 1 July 2023. Chatillon, A.; Theisen, Ch.; Greenlees, P. T.; Auger, G.; Bastin, J. E.; Bouchez, E.; Bouriquet, B.; Casandjian, J. M.; Cee, R.; Clément, E.; Dayras, R.; de France, G.; de Toureil, R.; Eeckhaudt, S.; Görgen, A.; Grahn, T.; Grévy, S.; Hauschild, K.; Herzberg, R. -D.; Ikin, P. J. C.; Jones, G. D.; Jones, P.; Julin, R.; Juutinen, S.; Kettunen, H.; Korichi, A.; Korten, W.; Le Coz, Y.; Leino, M.; Lopez-Martens, A.; Lukyanov, S. M.; Penionzhkevich, Yu. E.; Perkowski, J.; Pritchard, A.; Rahkila, P.; Rejmund, M.; Saren, J.; Scholey, C.; Siem, S.; Saint-Laurent, M. G.; Simenel, C.; Sobolev, Yu. G.; Stodel, Ch.; Uusitalo, J.; Villari, A.; Bender, M.; Bonche, P.; Heenen, P. -H. (1 November 2006). "Spectroscopy and single-particle structure of the odd- Z heavy elements 255Lr, 251Md and 247Es". The European Physical Journal A - Hadrons and Nuclei. 30 (2): 397–411. Bibcode:2006EPJA...30..397C. doi:10.1140/epja/i2006-10134-5. ISSN 1434-601X. S2CID 123346991. Retrieved 1 July 2023. Antalic, S.; Heßberger, F. P.; Ackermann, D.; Heinz, S.; Hofmann, S.; Kalaninová, Z.; Kindler, B.; Khuyagbaatar, J.; Kojouharov, I.; Kuusiniemi, P.; Leino, M.; Lommel, B.; Mann, R.; Nishio, K.; Šáro, Š.; Streicher, B.; Sulignano, B.; Venhart, M. (20 May 2011). "Isomeric states in 253No and 253Fm". The European Physical Journal A. 47 (5): 62. Bibcode:2011EPJA...47...62A. doi:10.1140/epja/i2011-11062-y. ISSN 1434-601X. S2CID 121080273.
- 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. S2CID 250839471.
- 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
- 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. S2CID 94982856.