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Isotopes of Mendelevium

List, data and properties of all known isotopes of Mendelevium.

Content
Atomic properties
Decay properties
NMR active nuclides
Radiation protection
References
Mendelevium isotopes

All of the atomic nuclei of the chemical element Mendelevium are summarized under Mendelevium isotopes; these consist of an atomic nucleus with 101 protons and in the uncharged state of 101 electrons. The difference between the individual Mendelevium isotopes lies in the number of neutrons in the nucleus.

 

Mendelevium is an exclusively synthetically produced radioactive chemical element that is not known in nature. So far, 16 different Md isotopes are known, of which the nuclide 258Md is the longest-lived with a half-life of 51.3 days.

 

Isotope Table: Mendelevium

The two following tables list the most important data and properties of the Mendelevium isotopes. Further information on the individual Mendelevium isotopes is listed on separate pages and can be accessed via the link in column 1.

 

Atomic Properties

Isotope
Nuclide		ENAtomic Mass
[Nuclear Mass]
{Mass Excess}		Spin I
(h/2π)		Parent
123456
Mendelevium-244244101Md143244.08116(40) u
[244.0257617 u]
{75.60005 MeV}
Mendelevium-244m244m101Md143244.08116(40) u
[244.0257617 u]
{75.60005 MeV}
Mendelevium-245245101Md144245.08081(33) u
[245.0254117 u]
{75.27403 MeV}		(1/2-)
Mendelevium-245m245m101Md144245.08081(33) u
[245.0254117 u]
{75.27403 MeV}		(7/2)
Mendelevium-246246101Md145246.08171(28) u
[246.0263117 u]
{76.11237 MeV}
Mendelevium-247247101Md146247.08152(22) u
[247.0261217 u]
{75.93539 MeV}		(7/2-)
Mendelevium-248248101Md147248.08282(25) u
[248.0274217 u]
{77.14633 MeV}
Mendelevium-249249101Md148249.08291(22) u
[249.0275117 u]
{77.23017 MeV}		(7/2-)253Lr
Mendelevium-249m249m101Md148249.08291(22) u
[249.0275117 u]
{77.23017 MeV}		(1/2-)
Mendelevium-250250101Md149250.08441(32) u
[250.0290117 u]
{78.62741 MeV}		254Lr
Mendelevium-251251101Md150251.084774(20) u
[251.0293757 u]
{78.96647 MeV}		(7/2-)255Lr
Mendelevium-252252101Md151252.08643(14) u
[252.0310317 u]
{80.50903 MeV}		256Lr
Mendelevium-253253101Md152253.08714(3) u
[253.0317417 u]
{81.17039 MeV}		(7/2-)257Lr
Mendelevium-254254101Md153254.08959(11) u
[254.0341917 u]
{83.45255 MeV}		258Lr
Mendelevium-254m254m101Md153254.08959(11) u
[254.0341917 u]
{83.45255 MeV}
Mendelevium-255255101Md154255.091083(7) u
[255.0356847 u]
{84.84327 MeV}		(7/2-)259Lr
255No
Mendelevium-256256101Md155256.09389(13) u
[256.0384917 u]
{87.45797 MeV}		(1-)260Lr
Mendelevium-257257101Md156257.0955380(17) u
[257.0401397 u]
{88.99307 MeV}		(7/2-)
Mendelevium-258258101Md157258.098430(5) u
[258.0430317 u]
{91.68695 MeV}		(8-)
Mendelevium-258m258m101Md157258.098430(5) u
[258.0430317 u]
{91.68695 MeV}		(1-)
Mendelevium-259259101Md158259.10051(21) u
[259.0451117 u]
{93.62446 MeV}		7/2-~259No
Mendelevium-260260101Md159260.10365(34) u
[260.0482517 u]
{96.54935 MeV}

 

Radioactive Decay Properties

IsotopeRadioactive DecayExtern
Half-lifeDecay ModeProbabilityEnergy
789101112
Md-2440.38 sα → 240Es
EC/β+ → 244Fm		> 86 %
< 14 %		8.947(79) MeV
6.633(425) MeV
Md-244m5 msα → 240Es
EC/β+ → 244Fm
SF div		?
?
?
Md-2450.90(25) msα → 241Es
SF → div		?
?		8.98(21) MeV
AL
Md-245mca. 0.35 sα → 241Es
EC/β+ → 245Fm		?
selten
AL
Md-2460.9(2) sα → 242Es
SF → div
EC → 246Fm		?
?
?		8.89(4) MeV

5.93(26) MeV		AL
Md-2471.2(1) sα → 243Es
SF div		> 99.9 %
< 0.1 %		8.764(10) MeV
AL
Md-2487(3) sα → 244Es
EC → 248Fm		20(10) %
80(10) %		8.70(15) MeV
5.25(24) MeV		AL
Md-24921.7(20) sα → 245Es
EC/β+ → 249Fm		> 60 %
≤ 40 %		8.441(18) MeV
3.71(20) MeV		AL
Md-249m1.9(9) sAL
Md-25052(6) sα → 246Es
EC → 250Fm		7(3) %
93(3) %		8.30(20) MeV
4.56(30) MeV		AL
Md-2514.0(5) minα → 247Es
EC/β+ → 251Fm		≤ 10 %
≥ 90 %		7.963(4) MeV
3.013(24) MeV		AL
Md-2522.3(8) minEC → 252Fm≤ 100 %3.69(13) MeVAL
Md-253ca. 6 minEC/β+ → 253Fm
α → 249Es		99.3 %
0.7 %		1.83(3) MeV
7.573(8) MeV		AL
Md-25410(3) minEC/β+ → 254Fm≤ 100 %2.55(10) MeVAL
Md-254m28(8) minEC/β+ → 254Fm≤ 100 %AL
Md-25527(2) minEC/β+ → 255Fm
α → 251Es		93(1) %
7(1) %		1.043(8) MeV
7.9059(26) MeV		AL
Md-25677.7(18) minEC → 256Fm
α → 252Es
SF div.		90.8(7) %
9.2(7) %
< 3 %		1.97(12) MeV
7.74(11) MeV
AL
Md-2575.52(5) hEC → 257Fm
α → 253Es
SF div		85 %
15 %
< 1 %		0.403(5) MeV
7.5576(10)
AL
Md-25851.50(29) dα → 254Es
SF, ε div		~100 %
≤ 0.003 %		7.2713(19) MeV
AL
Md-258m57.0(9) minEC → 258Fm
β- → 258No
SF, β- div
α → 254Es		70 %
10 %
20 %
< 1.2 %		1.26(20) MeV
0.210(100) MeV

7.2713(19) MeV		AL
Md-2591.60(6) hSF div
α → 255Es		< 100 %
< 1.3 %
7.11(20) MeV		AL
Md-26031.8(5) dSF div
α → 256Es
EC → 260Fm
β- → 260No
≤ 25 %
≤ 23 %
≤ 10 %
6.94(30) MeV

0.94(37) MeV		AL

 

Notes (related to the columns):

1 - name of the nuclide, isotope.
2 - E: isotope symbol with mass number (superscript; number of nucleons) and Atomic number (subscript; number of protons).
3 - N: number of neutrons.
4 - relative atomic mass of the Mendelevium isotope (isotopic mass including electrons) and the mass of the atomic nucleus in square brackets (nuclear mass, nuclide mass without electrons), each related to 12C = 12.00000 [2]. In addition, the mass excess is given in MeV.
5 - nuclear spin I, unit: h/2π.
6 - source nuclides: Possible, assumed or actual source nuclides (mother nuclides, parent nuclides). If applicable, the corresponding decay modes can be found in the data for the respective starting nuclide.

7 - isotope notation in short form.
8 - decay: half-live of the Mendelevium isotope (a = years; ; d = days; h = hours; min = minutes; s = seconds).
9 - decay mode: type of decay into the respective daughter nuclides with n = neutron emission; p = proton emission; α = alpha decay; β- = beta minus decay with electron emission; EC = electron capture; β+ = positron emission; ε = β+ and/or EC; Iso = isomeric transition; CD = cluster decay; SF = spontaneous decay.
10 - decay probability in percent (%).
11 - decay energy; Particle energy related to decay type.
12 - other information and notes: AL = Adopted Levels (link to external data [1]).

Miscellaneous:

()- Numbers in brackets: uncertainty to represent the spread of the reported value.
~ - Theoretical values or systematic trends.
  - unlisted-: Nuclides that have already been mentioned in the literature but for some reason can no longer be found in the current nuclide tables because their discovery e.g. has not confirmed.

 

Radiation Protection

According to the Radiation Protection Ordinance (StrlSchV 2018, Germany), the following values (columns 1 to 7) apply to the handling of Mendelevium radionuclides:

NuclideLimit ValueHASS limitSCDaughter NuclidesHalf-life
Md-257107 Bq10 Bq/g5.5 h
Md-258+105 Bq10 Bq/gFm-254, Fm-258, No-25851.5 h

(HASS = High-Activity Sealed Radioactive Sources; SC = surface contamination)

 

Literature Sources and References

Properties of the Mendelevium nucleides

[1] - NuDat: National Nuclear Data Center, Brookhaven National Laboratory, based on ENSDF and the Nuclear Wallet Cards.

[2] - G. Audi et. al.: The NUBASE evaluation of nuclear and decay properties. Nuclear Physics, (2003), DOI 10.1016/j.nuclphysa.2003.11.001.

[3] - Live Chart of Nuclides. Nuclear structure and decay data.

Mendelevium: NMR properties

[4] - N. J. Stone: Table of nuclear magnetic dipole and electric quadrupole moments. Atomic Data and Nuclear Data Tables, (2005), DOI 10.1016/j.adt.2005.04.001.

[5] - Pekka Pyykkö: Year-2008 nuclear quadrupole moments. Molecular Physics, (2008), DOI 10.1080/00268970802018367.

[6] - Pekka Pyykkö: Year-2017 nuclear quadrupole moments. Molecular Physics, (2018), DOI 10.1080/00268976.2018.1426131.

[7] - N. J. Stone: Table of recommended nuclear magnetic dipole moments. IAEA, (2019).

More sources:

[8] - Isotopic abundances, atomic weights and isotopic masses: see respective keyword.

 

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Last update: 2022-12-12

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