Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Isotopes of mendelevium
open-in-new
<h2 id="list-of-isotopes">List of isotopes</h2> <table><tbody><tr><th rowspan="2">Nuclide<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a></th><th rowspan="1"><a href="/facts/Atomic_number/bgAr581S"><i>Z</i></a></th><th rowspan="1"><a href="/facts/Neutron_number/eNtwGnVL"><i>N</i></a></th><th rowspan="1"><a href="/facts/Atomic_mass/J1FJY9MV">Isotopic mass</a> (<a href="/facts/Dalton_(unit)/IMATU3vf">Da</a>)<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a><a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a><a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a></th><th rowspan="2"><a href="/facts/Half-life/kGVH8BAB">Half-life</a><a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a></th><th rowspan="2"><a href="/facts/Decay_mode/Ya6FVjt4">Decaymode</a><a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a><a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a></th><th rowspan="2"><a href="/facts/Decay_product/hT0obfLv">Daughterisotope</a></th><th rowspan="2"><a href="/facts/Spin_(particle_physics)/4Jvp7e8P">Spin</a> and<a href="/facts/Parity_(physics)/emSbJ4hD">parity</a><a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a><a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a><a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a></th></tr><tr><th colspan="3">Excitation energy<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a></th></tr><tr><td rowspan="2">244Md<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a></td><td rowspan="2">101</td><td rowspan="2">143</td><td rowspan="2">244.08116(40)#</td><td rowspan="2">0.36(14) s</td><td><a href="/facts/Alpha_decay/rCsHNIUE">α</a></td><td>240Es</td><td rowspan="2">3+#</td></tr><tr><td><a href="/facts/Beta_decay/vxTBlckp">β+</a>, <a href="/facts/Spontaneous_fission/0QuJoVKI">SF</a> (<14%)</td><td>(various)</td></tr><tr><td>244mMd<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a></td><td colspan="3">200(150)# keV</td><td>~9 μs</td><td>IT</td><td>244Md</td><td>7+#</td></tr><tr><td>245Md</td><td>101</td><td>144</td><td>245.08086(28)#</td><td>0.38(10) s</td><td>α</td><td>241Es</td><td>(7/2−)</td></tr><tr><td>245mMd<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a></td><td colspan="3">100(100)# keV</td><td>0.90(25) ms</td><td>SF</td><td>(various)</td><td>1/2−#</td></tr><tr><td>246Md</td><td>101</td><td>145</td><td>246.08171(28)#</td><td>0.92(18) s</td><td>α</td><td>242Es</td><td>1−#</td></tr><tr><td rowspan="3">246mMd<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a></td><td rowspan="3" colspan="3">60(60) keV</td><td rowspan="3">4.4(8) s</td><td>β+ (~67%)</td><td>246Fm</td><td rowspan="3">4−#</td></tr><tr><td>α (<23%)</td><td>242Es</td></tr><tr><td>β+, SF (>10%)</td><td>(various)</td></tr><tr><td rowspan="2">247Md<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a></td><td rowspan="2">101</td><td rowspan="2">146</td><td rowspan="2">247.08152(22)#</td><td rowspan="2">1.20(12) s</td><td>α (99.14%)</td><td>243Es</td><td rowspan="2">(7/2−)</td></tr><tr><td>SF (0.86%)</td><td>(various)</td></tr><tr><td rowspan="2">247mMd</td><td rowspan="2" colspan="3">153 keV</td><td rowspan="2">0.23(3) s</td><td>α (80%)</td><td>243Es</td><td rowspan="2">(1/2−)</td></tr><tr><td>SF (20%)</td><td>(various)</td></tr><tr><td rowspan="3">248Md</td><td rowspan="3">101</td><td rowspan="3">147</td><td rowspan="3">248.08261(20)#</td><td rowspan="3">7(3) s</td><td>β+ (80%)</td><td>248Fm</td><td rowspan="3"></td></tr><tr><td>α (20%)</td><td>244Es</td></tr><tr><td>β+, SF (<0.05%)</td><td>(various)</td></tr><tr><td rowspan="2">249Md</td><td rowspan="2">101</td><td rowspan="2">148</td><td rowspan="2">249.08286(18)</td><td rowspan="2">25.6(9) s</td><td>α (75%)</td><td>245Es</td><td rowspan="2">(7/2−)</td></tr><tr><td>β+ (25%)</td><td>249Fm</td></tr><tr><td>249mMd<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a></td><td colspan="3">100(100)# keV</td><td>1.9(9) s</td><td>α</td><td>245Es</td><td>(1/2−)</td></tr><tr><td rowspan="3">250Md</td><td rowspan="3">101</td><td rowspan="3">149</td><td rowspan="3">250.084165(98)</td><td rowspan="3">54(4) s</td><td>β+ (93.0%)</td><td>250Fm</td><td rowspan="3">2−#</td></tr><tr><td>α (7.0%)</td><td>246Es</td></tr><tr><td>β+, SF (0.026%)</td><td>(various)</td></tr><tr><td>250mMd</td><td colspan="3">120(40) keV</td><td>42.4(45) s</td><td>α</td><td>246Es</td><td>7+#</td></tr><tr><td rowspan="2">251Md</td><td rowspan="2">101</td><td rowspan="2">150</td><td rowspan="2">251.084774(20)</td><td rowspan="2">4.21(23) min</td><td>β+ (90%)</td><td>251Fm</td><td rowspan="2">(7/2−)</td></tr><tr><td>α (10%)</td><td>247Es</td></tr><tr><td>251mMd</td><td colspan="3">53(8) keV</td><td>20# s</td><td></td><td></td><td>(1/2−)</td></tr><tr><td>252Md</td><td>101</td><td>151</td><td>252.086385(98)</td><td>2.3(8) min</td><td>β+</td><td>252Fm</td><td>1+#</td></tr><tr><td rowspan="2">253Md</td><td rowspan="2">101</td><td rowspan="2">152</td><td rowspan="2">253.087143(34)#</td><td rowspan="2">12(8) min</td><td>β+ (~99.3%)</td><td>253Fm</td><td rowspan="2">(7/2−)</td></tr><tr><td>α (~0.7%)</td><td>249Es</td></tr><tr><td>253mMd</td><td colspan="3">60(30) keV</td><td>1# min</td><td></td><td></td><td>(1/2−)</td></tr><tr><td>254Md</td><td>101</td><td>153</td><td>254.08959(11)#</td><td>10(3) min</td><td>β+</td><td>254Fm</td><td>0−#</td></tr><tr><td>254mMd<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a></td><td colspan="3">50(100)# keV</td><td>28(8) min</td><td>β+</td><td>254Fm</td><td>3−#</td></tr><tr><td rowspan="2">255Md</td><td rowspan="2">101</td><td rowspan="2">154</td><td rowspan="2">255.0910817(60)</td><td rowspan="2">27(2) min</td><td>β+ (93%)</td><td>255Fm</td><td rowspan="2">7/2−</td></tr><tr><td>α (7%)</td><td>251Es</td></tr><tr><td rowspan="3">256Md</td><td rowspan="3">101</td><td rowspan="3">155</td><td rowspan="3">256.09389(13)#</td><td rowspan="3">77.7(18) min</td><td>β+ (90.8%)</td><td>256Fm</td><td rowspan="3">(1−)</td></tr><tr><td>α (9.2%)</td><td>252Es</td></tr><tr><td>SF (<3%)</td><td>(various)</td></tr><tr><td rowspan="2">257Md</td><td rowspan="2">101</td><td rowspan="2">156</td><td rowspan="2">257.0955373(17)</td><td rowspan="2">5.52(5) h</td><td><a href="/facts/Electron_capture/EIccoV1u">EC</a> (85%)</td><td>257Fm</td><td rowspan="2">(7/2−)</td></tr><tr><td>α (15%)</td><td>253Es</td></tr><tr><td rowspan="3">258Md</td><td rowspan="3">101</td><td rowspan="3">157</td><td rowspan="3">258.0984336(37)</td><td rowspan="3">51.59(29) d</td><td>α</td><td>254Es</td><td rowspan="3">(8−)#</td></tr><tr><td>β− (<0.0015%)</td><td>258No</td></tr><tr><td>β+ (<0.0015%)</td><td>258Fm</td></tr><tr><td rowspan="3">258mMd<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a></td><td rowspan="3" colspan="3">0(200)# keV</td><td rowspan="3">57.0(9) min</td><td>EC (85%)</td><td>258Fm</td><td rowspan="3">1−#</td></tr><tr><td>SF (<15%)</td><td>(various)</td></tr><tr><td>α (<1.2%)</td><td>254Es</td></tr><tr><td>259Md<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a></td><td>101</td><td>158</td><td>259.10045(11)#</td><td>1.60(6) h</td><td>SF</td><td>(various)</td><td>7/2−#</td></tr><tr><td rowspan="4">260Md</td><td rowspan="4">101</td><td rowspan="4">159</td><td rowspan="4">260.10365(34)#</td><td rowspan="4">27.8(8) d</td><td>SF</td><td>(various)</td><td rowspan="4"></td></tr><tr><td>α (<5%)</td><td>256Es</td></tr><tr><td>EC (<5%)</td><td>260Fm</td></tr><tr><td>β− (<3.5%)</td><td>260No</td></tr><tr><th colspan="20"><i>This table header & footer:</i> <ul><li>view</li></ul></th></tr></tbody></table> <h2 id="chronology-of-isotope-discovery">Chronology of isotope discovery</h2> <table><tbody><tr><th>Isotope</th><th>Discovered</th><th>Reaction</th></tr><tr><td>244Md</td><td>2020</td><td>209Bi(40Ar,5n)</td></tr><tr><td>245Md</td><td>1996</td><td>209Bi(40Ar,4n)</td></tr><tr><td>246Md</td><td>1996</td><td>209Bi(40Ar,3n)</td></tr><tr><td>247Md</td><td>1981</td><td>209Bi(40Ar,2n)</td></tr><tr><td>248Md</td><td>1973</td><td>241Am(12C,5n)</td></tr><tr><td>249Md</td><td>1973</td><td>241Am(12C,4n)</td></tr><tr><td>250Md</td><td>1973</td><td>243Am(12C,5n), 243Am(13C,6n)</td></tr><tr><td>251Md</td><td>1973</td><td>243Am(12C,4n), 243Am(13C,5n)</td></tr><tr><td>252Md</td><td>1973</td><td>243Am(13C,4n)</td></tr><tr><td>253Md</td><td>1992</td><td>243Am(13C,3n)</td></tr><tr><td>254Md</td><td>1970</td><td>253Es(α,3n)</td></tr><tr><td>255Md</td><td>1958</td><td>253Es(α,2n)</td></tr><tr><td>256Md</td><td>1955</td><td>253Es(α,n)</td></tr><tr><td>257Md</td><td>1964</td><td>252Cf(11B,α2n)</td></tr><tr><td>258Md</td><td>1970</td><td>255Es(α,n)</td></tr><tr><td>259Md</td><td>1982</td><td>248Cm(18O,α3n)<a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a></td></tr><tr><td>260Md</td><td>1989</td><td>254Es+18O, 22Ne — transfer</td></tr></tbody></table> <ul><li>Isotope masses from: <ul><li>M. Wang; G. Audi; A. H. Wapstra; F. G. Kondev; M. MacCormick; X. Xu; et al. (2012). <a href="http://amdc.in2p3.fr/masstables/Ame2012/Ame2012b-v2.pdf">"The AME2012 atomic mass evaluation (II). Tables, graphs and references"</a> (PDF). <i>Chinese Physics C</i>. 36 (12): 1603–2014. <a href="/facts/Bibcode_(identifier)/9HtdQSGB">Bibcode</a>:<a href="https://ui.adsabs.harvard.edu/abs/2012ChPhC..36....3M">2012ChPhC..36....3M</a>. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1088%2F1674-1137%2F36%2F12%2F003">10.1088/1674-1137/36/12/003</a>. <a href="/facts/S2CID_(identifier)/ldJsHa2Y">S2CID</a> <a href="https://api.semanticscholar.org/CorpusID:250839471">250839471</a>.</li> <li>Audi, Georges; Bersillon, Olivier; Blachot, Jean; <a href="/facts/Aaldert_Wapstra/9Ylvt18s">Wapstra, Aaldert Hendrik</a> (2003), <a href="https://hal.archives-ouvertes.fr/in2p3-00020241/document">"The NUBASE evaluation of nuclear and decay properties"</a>, <i>Nuclear Physics A</i>, 729: 3–128, <a href="/facts/Bibcode_(identifier)/9HtdQSGB">Bibcode</a>:<a href="https://ui.adsabs.harvard.edu/abs/2003NuPhA.729....3A">2003NuPhA.729....3A</a>, <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1016%2Fj.nuclphysa.2003.11.001">10.1016/j.nuclphysa.2003.11.001</a></li></ul></li> <li>Half-life, spin, and isomer data selected from the following sources. <ul><li>Audi, Georges; Bersillon, Olivier; Blachot, Jean; <a href="/facts/Aaldert_Wapstra/9Ylvt18s">Wapstra, Aaldert Hendrik</a> (2003), <a href="https://hal.archives-ouvertes.fr/in2p3-00020241/document">"The NUBASE evaluation of nuclear and decay properties"</a>, <i>Nuclear Physics A</i>, 729: 3–128, <a href="/facts/Bibcode_(identifier)/9HtdQSGB">Bibcode</a>:<a href="https://ui.adsabs.harvard.edu/abs/2003NuPhA.729....3A">2003NuPhA.729....3A</a>, <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1016%2Fj.nuclphysa.2003.11.001">10.1016/j.nuclphysa.2003.11.001</a></li> <li><a href="/facts/National_Nuclear_Data_Center/SgVzvxLk">National Nuclear Data Center</a>. <a href="http://www.nndc.bnl.gov/nudat2/">"NuDat 2.x database"</a>. <a href="/facts/Brookhaven_National_Laboratory/L2JrG0K1">Brookhaven National Laboratory</a>.</li> <li>Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). <i><a href="/facts/CRC_Handbook_of_Chemistry_and_Physics/qjxzC2Cu">CRC Handbook of Chemistry and Physics</a></i> (85th ed.). <a href="/facts/Boca_Raton,_Florida/9gcNen3S">Boca Raton, Florida</a>: <a href="/facts/CRC_Press/duTuH4hz">CRC Press</a>. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-8493-0485-9.</li> <li>M. Thoennessen (2012). "Discovery of Isotopes of Elements with Z≥100". <i>Atomic Data and Nuclear Data Tables</i>. 99 (3): 312–344. <a href="/facts/ArXiv_(identifier)/H6EtgnBe">arXiv</a>:<a href="https://arxiv.org/abs/1203.2105">1203.2105</a>. <a href="/facts/Bibcode_(identifier)/9HtdQSGB">Bibcode</a>:<a href="https://ui.adsabs.harvard.edu/abs/2013ADNDT..99..312T">2013ADNDT..99..312T</a>. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1016%2Fj.adt.2012.03.003">10.1016/j.adt.2012.03.003</a>. <a href="/facts/S2CID_(identifier)/ldJsHa2Y">S2CID</a> <a href="https://api.semanticscholar.org/CorpusID:94982856">94982856</a>.</li></ul></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>mMd – Excited nuclear isomer. <a href="/wiki/Nuclear_isomer" target="_blank">/wiki/Nuclear_isomer</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>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. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits. <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p># – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS). <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>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. <a href="https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf" target="_blank">https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>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. <a href="https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf" target="_blank">https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Modes of decay: EC:Electron captureSF:Spontaneous fission <a href="/wiki/Electron_capture" target="_blank">/wiki/Electron_capture</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>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. <a href="https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf" target="_blank">https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>( ) spin value – Indicates spin with weak assignment arguments. <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p># – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN). <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p># – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN). <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Discovery of this isotope is disputed due to conflicting data.[3] <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Discovery of this isotope is disputed due to conflicting data.[3] <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Order of ground state and isomer is uncertain. <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Order of ground state and isomer is uncertain. <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>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. <a href="https://doi.org/10.1140%2Fepja%2Fs10050-022-00663-4" target="_blank">https://doi.org/10.1140%2Fepja%2Fs10050-022-00663-4</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>Order of ground state and isomer is uncertain. <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>Order of ground state and isomer is uncertain. <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>Order of ground state and isomer is uncertain. <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>Not directly synthesized, occurs as decay product of 259No <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> <li id="fn:21"><p>see nobelium <a href="/wiki/Nobelium" target="_blank">/wiki/Nobelium</a> <a href="#fnref:21" class="footnote-back-ref">↩</a></p></li> </ol>