Isotopes of mendelevium

{{Short description|none}} {{Infobox mendelevium isotopes}} 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 10 isomers. The longest-lived isotope is ²⁵⁸Md with a half-life of 51.6 days, and the longest-lived isomer is ^258mMd with a half-life of 57 minutes.

== List of isotopes == {{Anchor|Mendelevium-256m|Mendelevium-261|Mendelevium-262}}

<!--Please delete anchor(s) from the list above or table below if adding a dedicated isotope section(s).-->

{{Isotopes table |symbol=Md |refs=NUBASE2020, AME2020 II,<!--updated 2024-09-30--> IsotopeFRIB, IsomerFRIB |notes=m, unc(), mass#, exen#, spin(), spin#, SF, EC, discoveryname }} |-id=Mendelevium-244 | rowspan=2|²⁴⁴Md{{refn|group=n|name=244md|Discovery of this isotope is disputed due to conflicting data.<ref>{{cite journal |last1=Heßberger |first1=F. P. |last2=Block |first2=M. |last3=Düllmann |first3=Ch. E. |last4=Yakushev |first4=A. |last5=Leino |first5=M. |last6=Uusitalo |first6=J. |title=Some Remarks on the Discovery of Md 244 |journal=Physical Review Letters |date=3 May 2021 |volume=126 |issue=18 |article-number=182501 |doi=10.1103/PhysRevLett.126.182501|pmid=34018761 |arxiv=2101.06076 }}</ref>}} | rowspan=2 style="text-align:right" | 101 | rowspan=2 style="text-align:right" | 143 | rowspan=2|244.08116(40)# | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/244.pdf 2020] | rowspan=2|{{val|0.30|0.19|0.09|u=s}}<br>[{{val|0.36|(14)|u=s}}] | α | ²⁴⁰Es | rowspan=2|3+# |- | β⁺, SF (<14%) | (various) |-id=Mendelevium-244m | style="text-indent:1em" | ^244mMd<ref group="n" name="244md"/> | colspan="3" style="text-indent:2em" | 200(150)#&nbsp;keV | style="text-align:center" | (2020)<ref group="n"> Half-life only estimated, not included in discovery database </ref> | ~9&nbsp;μs | IT | ²⁴⁴Md | 7+# |-id=Mendelevium-245 | ²⁴⁵Md | style="text-align:right" | 101 | style="text-align:right" | 144 | 245.08086(28)# | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/245.pdf 1996] | 0.38(10)&nbsp;s | α | ²⁴¹Es | (7/2−) |-id=Mendelevium-245m | style="text-indent:1em" | ^245mMd<ref group="n" name="order">Order of ground state and isomer is uncertain.</ref> | colspan="3" style="text-indent:2em" | 100(100)#&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/101/245Md-1.pdf 1996] | 0.90(25)&nbsp;ms | SF | (various) | 1/2−# |-id=Mendelevium-246 | ²⁴⁶Md | style="text-align:right" | 101 | style="text-align:right" | 145 | 246.08171(28)# | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/246.pdf 1996] | 0.92(18)&nbsp;s | α | ²⁴²Es | 1−# |-id=Mendelevium-246m | rowspan=3 style="text-indent:1em" | ^246mMd<ref group="n" name="order"/> | rowspan=3 colspan="3" style="text-indent:2em" | 60(60)&nbsp;keV | rowspan=3 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/101/246Md-1.pdf 2010] | rowspan=3|{{val|4.4|(8)|u=s}} | β⁺ (~67%) | ²⁴⁶Fm | rowspan=3|4−# |- | α (<23%) | ²⁴²Es |- | β⁺, SF (>10%) | (various) |-id=Mendelevium-247 | rowspan=2|²⁴⁷Md | rowspan=2 style="text-align:right" | 101 | rowspan=2 style="text-align:right" | 146 | rowspan=2|247.08152(22)# | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/247.pdf 1981] | rowspan=2|{{val|1.20|(12)|u=s}}<ref name=247Md>{{cite journal |last1=Heßberger |first1=F. P. |last2=Antalic |first2=S. |last3=Giacoppo |first3=F. |last4=Andel |first4=B. |last5=Ackermann |first5=D. |last6=Block |first6=M. |last7=Heinz |first7=S. |last8=Khuyagbaatar |first8=J. |last9=Kojouharov |first9=I. |last10=Venhart |first10=M. |title=Alpha-gamma decay studies of ²⁴⁷Md |journal=The European Physical Journal A |date=25 January 2022 |volume=58 |issue=1 |pages=11 |doi=10.1140/epja/s10050-022-00663-4 |bibcode=2022EPJA...58...11H |s2cid=246281669 |issn=1434-601X|doi-access=free }}</ref> | α (99.14%) | ²⁴³Es | rowspan=2|(7/2−) |- | SF (0.86%)<ref name=247Md/> | (various) |-id=Mendelevium-247m | rowspan=2 style="text-indent:1em" | ^247mMd<ref name=247Md/> | rowspan=2 colspan="3" style="text-indent:2em" | 153&nbsp;keV | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/101/247Md-1.pdf 2010] | rowspan=2|{{val|0.23|(3)|u=s}} | α (80%) | ²⁴³Es | rowspan=2|(1/2−) |- | SF (20%) | (various) |-id=Mendelevium-248 | rowspan=3|²⁴⁸Md | rowspan=3 style="text-align:right" | 101 | rowspan=3 style="text-align:right" | 147 | rowspan=3|248.08261(20)# | rowspan=3 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/248.pdf 1973] | rowspan=3|{{val|7|(3)|u=s}} | β⁺ (80%) | ²⁴⁸Fm | rowspan=3| |- | α (20%) | ²⁴⁴Es |- | β⁺, SF (<0.05%) | (various) |-id=Mendelevium-249 | rowspan=2|²⁴⁹Md | rowspan=2 style="text-align:right" | 101 | rowspan=2 style="text-align:right" | 148 | rowspan=2|249.08286(18) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/249.pdf 1973] | rowspan=2|{{val|25.6|(9)|u=s}} | α (75%) | ²⁴⁵Es | rowspan=2|(7/2−) |- | β⁺ (25%) | ²⁴⁹Fm |-id=Mendelevium-249m1 | style="text-indent:1em" | ^249m1Md<ref group="n" name="order"/> | colspan="3" style="text-indent:2em" | 100(100)#&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/101/249Md-1.pdf 2001] | {{val|1.5|1.2|0.5|u=s}}<br>[{{val|1.9|(9)|u=s}}] | α | ²⁴⁵Es | (1/2−) |-id=Mendelevium-249m2 | style="text-indent:1em" | ^249m2Md | colspan="3" style="text-indent:2em" | ≥910#&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/101/249Md-2.pdf 2021] | 2.8(5)&nbsp;ms | | | (19/2−) |-id=Mendelevium-250 | rowspan=3|²⁵⁰Md | rowspan=3 style="text-align:right" | 101 | rowspan=3 style="text-align:right" | 149 | rowspan=3|250.084165(98) | rowspan=3 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/250.pdf 1973] | rowspan=3|54(4)&nbsp;s | β⁺ (93.0%) | ²⁵⁰Fm | rowspan=3|2−# |- | α (7.0%) | ²⁴⁶Es |- | β⁺, SF (0.026%) | (various) |-id=Mendelevium-250m | style="text-indent:1em" | ^250mMd | colspan="3" style="text-indent:2em" | 120(40)&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/101/250Md-1.pdf 2019] | 42.4(45)&nbsp;s | α | ²⁴⁶Es | 7+# |-id=Mendelevium-251 | rowspan=2|²⁵¹Md | rowspan=2 style="text-align:right" | 101 | rowspan=2 style="text-align:right" | 150 | rowspan=2|251.084774(20) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/251.pdf 1973] | rowspan=2|{{val|4.21|(23)|u=min}} | β⁺ (90%) | ²⁵¹Fm | rowspan=2|(7/2−) |- | α (10%) | ²⁴⁷Es |-id=Mendelevium-251m | style="text-indent:1em" | ^251mMd | colspan="3" style="text-indent:2em" | 53(8)&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/101/251Md-1.pdf 2021] | 20#&nbsp;s | | | (1/2−) |-id=Mendelevium-252 | ²⁵²Md | style="text-align:right" | 101 | style="text-align:right" | 151 | 252.086385(98) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/252.pdf 1973] | {{val|2.3|(8)|u=min}} | β⁺ | ²⁵²Fm | 1+# |-id=Mendelevium-253 | rowspan=2|²⁵³Md | rowspan=2 style="text-align:right" | 101 | rowspan=2 style="text-align:right" | 152 | rowspan=2|253.087143(34)# | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/253.pdf 1992] | rowspan=2|{{val|6.4|11.6|3.6|u=min}}<br>[{{val|12|(8)|u=min}}] | β⁺ (~99.3%) | ²⁵³Fm | rowspan=2|(7/2−) |- | α (~0.7%) | ²⁴⁹Es |-id=Mendelevium-253m | style="text-indent:1em" | ^253mMd | colspan="3" style="text-indent:2em" | 60(30)&nbsp;keV | style="text-align:center" | (1971)<ref group="n"> Half-life not measured, not included in discovery database </ref> | 1#&nbsp;min | | | 1/2−# |-id=Mendelevium-254 | ²⁵⁴Md | style="text-align:right" | 101 | style="text-align:right" | 153 | 254.08959(11)# | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/254.pdf 1970] | {{val|10|(3)|u=min}} | β⁺ | ²⁵⁴Fm | 0−# |-id=Mendelevium-254m | style="text-indent:1em" | ^254mMd<ref group="n" name="order"/> | colspan="3" style="text-indent:2em" | 50(100)#&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/101/254Md-1.pdf 1970] | {{val|28|(8)|u=min}} | β⁺ | ²⁵⁴Fm | 3−# |-id=Mendelevium-255 | rowspan=2|²⁵⁵Md | rowspan=2 style="text-align:right" | 101 | rowspan=2 style="text-align:right" | 154 | rowspan=2|255.0910817(60) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/255.pdf 1958] | rowspan=2|{{val|27|(2)|u=min}} | β⁺ (93%) | ²⁵⁵Fm | rowspan=2|7/2− |- | α (7%) | ²⁵¹Es |-id=Mendelevium-256 | rowspan=3|²⁵⁶Md | rowspan=3 style="text-align:right" | 101 | rowspan=3 style="text-align:right" | 155 | rowspan=3|256.09389(13)# | rowspan=3 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/256.pdf 1955] | rowspan=3|{{val|77.7|(18)|u=min}} | β⁺ (90.8%) | ²⁵⁶Fm | rowspan=3|(1−) |- | α (9.2%) | ²⁵²Es |- | SF (<3%) | (various) |-id=Mendelevium-257 | rowspan=2|²⁵⁷Md | rowspan=2 style="text-align:right" | 101 | rowspan=2 style="text-align:right" | 156 | rowspan=2|257.0955373(17) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/257.pdf 1965] | rowspan=2|{{val|5.52|(5)|u=h}} | EC (85%) | ²⁵⁷Fm | rowspan=2|(7/2−) |- | α (15%) | ²⁵³Es |-id=Mendelevium-258 | rowspan=3|²⁵⁸Md | rowspan=3 style="text-align:right" | 101 | rowspan=3 style="text-align:right" | 157 | rowspan=3|258.0984336(37) | rowspan=3 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/258.pdf 1970] | rowspan=3|{{val|51.59|(29)|u=d}} | α | ²⁵⁴Es | rowspan=3|8−# |- | β⁻ (<0.0015%) | ²⁵⁸No |- | β⁺ (<0.0015%) | ²⁵⁸Fm |-id=Mendelevium-258m | rowspan=3 style="text-indent:1em" | ^258mMd<ref group="n" name="order"/> | rowspan=3 colspan="3" style="text-indent:2em" | 0(200)#&nbsp;keV | rowspan=3 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/101/258Md-1.pdf 1980] | rowspan=3|{{val|57.0|(9)|u=min}} | EC (85%) | ²⁵⁸Fm | rowspan=3|1−# |- | SF (<15%) | (various) |- | α (<1.2%) | ²⁵⁴Es |-id=Mendelevium-259 | ²⁵⁹Md<ref group="n">Not directly synthesized, occurs as decay product of ²⁵⁹No</ref> | style="text-align:right" | 101 | style="text-align:right" | 158 | 259.10045(11)# | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/259.pdf 1982] | {{val|1.60|(6)|u=h}} | SF | (various) | 7/2−# |-id=Mendelevium-260 | rowspan=4|²⁶⁰Md | rowspan=4 style="text-align:right" | 101 | rowspan=4 style="text-align:right" | 159 | rowspan=4|260.10365(34)# | rowspan=4 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/101/260.pdf 1989] | rowspan=4|{{val|27.8|(8)|u=d}} | SF | (various) | rowspan=4| |- | α (<5%) | ²⁵⁶Es |- | EC (<5%) | ²⁶⁰Fm |- | β⁻ (<3.5%) | ²⁶⁰No {{Isotopes table/footer}}

== Chronology of isotope discovery ==

{| class="wikitable" ! Isotope !! Discovered !! Reaction |-id=Mendelevium-244 | ²⁴⁴Md|| 2020|| ²⁰⁹Bi(⁴⁰Ar,5n) |- | ²⁴⁵Md|| 1996|| ²⁰⁹Bi(⁴⁰Ar,4n) |- | ²⁴⁶Md|| 1996|| ²⁰⁹Bi(⁴⁰Ar,3n) |-id=Mendelevium-247 | ²⁴⁷Md|| 1981|| ²⁰⁹Bi(⁴⁰Ar,2n) |-id=Mendelevium-248 | ²⁴⁸Md|| 1973|| ²⁴¹Am(¹²C,5n) |-id=Mendelevium-249 | ²⁴⁹Md|| 1973|| ²⁴¹Am(¹²C,4n) |-id=Mendelevium-250 | ²⁵⁰Md|| 1973|| ²⁴³Am(¹²C,5n), ²⁴³Am(¹³C,6n) |-id=Mendelevium-251 | ²⁵¹Md|| 1973|| ²⁴³Am(¹²C,4n), ²⁴³Am(¹³C,5n) |- | ²⁵²Md|| 1973|| ²⁴³Am(¹³C,4n) |-id=Mendelevium-253 | ²⁵³Md|| 1992|| ²⁴³Am(¹³C,3n) |- | ²⁵⁴Md|| 1970|| ²⁵³Es(α,3n) |-id=Mendelevium-255 | ²⁵⁵Md|| 1958|| ²⁵³Es(α,2n) |-id=Mendelevium-256 | ²⁵⁶Md|| 1955|| ²⁵³Es(α,n) |-id=Mendelevium-257 | ²⁵⁷Md|| 1964|| ²⁵²Cf(¹¹B,α2n) |-id=Mendelevium-258 | ²⁵⁸Md|| 1970|| ²⁵⁵Es(α,n) |- | ²⁵⁹Md|| 1982|| ²⁴⁸Cm(¹⁸O,α3n)<ref>see nobelium</ref> |-id=Mendelevium-260 | ²⁶⁰Md|| 1989|| ²⁵⁴Es+¹⁸O, ²²Ne — transfer |}

== References == {{Reflist}} * Isotope masses from: **{{cite journal |author=M. Wang |author2=G. Audi |author3=A. H. Wapstra |author4=F. G. Kondev |author5=M. MacCormick |author6=X. Xu |year=2012 |title=The AME2012 atomic mass evaluation (II). Tables, graphs and references. |url=http://amdc.in2p3.fr/masstables/Ame2012/Ame2012b-v2.pdf |journal=Chinese Physics C |volume=36 |issue=12 |pages=1603–2014 |doi=10.1088/1674-1137/36/12/003 |bibcode=2012ChPhC..36....3M |s2cid=250839471 |display-authors=etal |archive-date=2013-09-28 |access-date=2013-07-03 |archive-url=https://web.archive.org/web/20130928040033/http://amdc.in2p3.fr/masstables/Ame2012/Ame2012b-v2.pdf |url-status=dead }} **{{NUBASE 2003}} * Half-life, spin, and isomer data selected from the following sources. **{{NUBASE 2003}} **{{NNDC}} **{{CRC85|chapter=11}} **{{cite journal |author=M. Thoennessen |year=2012 |title=Discovery of Isotopes of Elements with Z≥100 |arxiv=1203.2105 |doi=10.1016/j.adt.2012.03.003 |volume=99 |issue=3 |journal=Atomic Data and Nuclear Data Tables |pages=312–344|bibcode=2013ADNDT..99..312T |s2cid=94982856 }}

{{Navbox element isotopes}}

Category:Isotopes of mendelevium Category:Mendelevium Mendelevium