Isotopes of mendelevium#Mendelevium-260

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.

List of isotopes

{{Isotopes table

|symbol=Md

|refs=NUBASE2020, AME2020 II

|notes=m, unc(), mass#, exen#, spin(), spin#, SF, EC,

}}

|-id=Mendelevium-244

| rowspan=2|²⁴⁴Md{{refn|group=n|name=244md|Discovery of this isotope is disputed due to conflicting data.{{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 |doi=10.1103/PhysRevLett.126.182501|arxiv=2101.06076 }}}}

| rowspan=2 style="text-align:right" | 101

| rowspan=2 style="text-align:right" | 143

| rowspan=2|244.08116(40)#

| rowspan=2|{{val|0.30|0.19|0.09|u=s}}
[{{val|0.36|(14)|u=s}}]

| α

| ²⁴⁰Es

| rowspan=2|3+#

| β⁺, SF (<14%)

| (various)

|-id=Mendelevium-244m

| style="text-indent:1em" | ^244mMd

| colspan="3" style="text-indent:2em" | 200(150)# keV

| ~9 μs

| IT

| ²⁴⁴Md

| 7+#

|-id=Mendelevium-245

| ²⁴⁵Md

| style="text-align:right" | 101

| style="text-align:right" | 144

| 245.08086(28)#

| 0.38(10) s

| α

| ²⁴¹Es

| (7/2−)

|-id=Mendelevium-245m

| style="text-indent:1em" | ^245mMdOrder of ground state and isomer is uncertain.

| colspan="3" style="text-indent:2em" | 100(100)# keV

| 0.90(25) ms

| SF

| (various)

| 1/2−#

|-id=Mendelevium-246

| ²⁴⁶Md

| style="text-align:right" | 101

| style="text-align:right" | 145

| 246.08171(28)#

| 0.92(18) s

| α

| ²⁴²Es

| 1−#

|-id=Mendelevium-246m

| rowspan=3 style="text-indent:1em" | ^246mMd

| rowspan=3 colspan="3" style="text-indent:2em" | 60(60) keV

| 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|{{val|1.20|(12)|u=s}}{{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 }}

| α (99.14%)

| ²⁴³Es

| rowspan=2|(7/2−)

| SF (0.86%)

| (various)

|-id=Mendelevium-247m

| rowspan=2 style="text-indent:1em" | ^247mMd

| rowspan=2 colspan="3" style="text-indent:2em" | 153 keV

| 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|{{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|{{val|25.6|(9)|u=s}}

| α (75%)

| ²⁴⁵Es

| rowspan=2|(7/2−)

| β⁺ (25%)

| ²⁴⁹Fm

|-id=Mendelevium-249m

| style="text-indent:1em" | ^249mMd

| colspan="3" style="text-indent:2em" | 100(100)# keV

| {{val|1.5|1.2|0.5|u=s}}
[{{val|1.9|(9)|u=s}}]

| α

| ²⁴⁵Es

| (1/2−)

|-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|54(4) 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) keV

| 42.4(45) 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|{{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) keV

| 20# s

| (1/2−)

|-id=Mendelevium-252

| ²⁵²Md

| style="text-align:right" | 101

| style="text-align:right" | 151

| 252.086385(98)

| {{val|2.3|(8)|u=min}}

| β⁺

| ²⁵²Fm

| 1+#

| rowspan=2|²⁵³Md

| rowspan=2 style="text-align:right" | 101

| rowspan=2 style="text-align:right" | 152

| rowspan=2|253.087143(34)#

| rowspan=2|{{val|6.4|11.6|3.6|u=min}}
[{{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) keV

| 1# min

| 1/2−#

|-id=Mendelevium-254

| ²⁵⁴Md

| style="text-align:right" | 101

| style="text-align:right" | 153

| 254.08959(11)#

| {{val|10|(3)|u=min}}

| β⁺

| ²⁵⁴Fm

| 0−#

|-id=Mendelevium-254m

| style="text-indent:1em" | ^254mMd

| colspan="3" style="text-indent:2em" | 50(100)# keV

| {{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|{{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|{{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|{{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|{{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

| rowspan=3 colspan="3" style="text-indent:2em" | 0(200)# keV

| rowspan=3|{{val|57.0|(9)|u=min}}

| EC (85%)

| ²⁵⁸Fm

| rowspan=3|1−#

| SF (<15%)

| (various)

| α (<1.2%)

| ²⁵⁴Es

|-id=Mendelevium-259

| ²⁵⁹MdNot directly synthesized, occurs as decay product of ²⁵⁹No

| style="text-align:right" | 101

| style="text-align:right" | 158

| 259.10045(11)#

| {{val|1.60|(6)|u=h}}

| SF

| (various)

| 7/2−#

| rowspan=4|²⁶⁰Md

| rowspan=4 style="text-align:right" | 101

| rowspan=4 style="text-align:right" | 159

| rowspan=4|260.10365(34)#

| rowspan=4|{{val|27.8|(8)|u=d}}

| SF

| (various)

| rowspan=4|

| α (<5%)

| ²⁵⁶Es

| EC (<5%)

| ²⁶⁰Fm

| β⁻ (<3.5%)

| ²⁶⁰No

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)see nobelium
id=Mendelevium-260 \| ²⁶⁰Md	1989	²⁵⁴Es+¹⁸O, ²²Ne — transfer

References

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}}
{{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 }}

Category:Mendelevium

Mendelevium