Isotopes of mendelevium

Main isotopes of mendelevium (₁₀₁Md)
α	253Es
SF	–
ε	258Fm
β−	258No
α	255Es
α	256Es
ε	260Fm
β−	260No
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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[]

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]}
Nuclide ^{[n 1]}	Excitation energy^{[n 6]}			Half-life	Decay mode ^{[n 4]}	Daughter isotope	Spin and parity ^{[n 5]}^{[n 6]}
²⁴⁴Md^[1]	101	143		0.36(0.14) s	α	²⁴⁰Es
²⁴⁵Md	101	144	245.08081(33)#	0.90(25) ms	SF	(various)	(1/2−)#
²⁴⁵Md	101	144	245.08081(33)#	0.90(25) ms	α (rare)	²⁴¹Es	(1/2−)#
^245mMd	200(100)# keV			400(200) ms [0.35(+23−16) s]	α	²⁴¹Es	(7/2+)
^245mMd	200(100)# keV			400(200) ms [0.35(+23−16) s]	β⁺ (rare)	²⁴⁵Fm	(7/2+)
²⁴⁶Md	101	145	246.08171(28)#	1.0(4) s	α	²⁴²Es
²⁴⁶Md	101	145	246.08171(28)#	1.0(4) s	β⁺ (rare)	²⁴⁶Fm
²⁴⁷Md	101	146	247.08152(22)#	1.12(22) s	SF	(various)	1/2−#
²⁴⁷Md	101	146	247.08152(22)#	1.12(22) s	α (rare)	²⁴³Es	1/2−#
^247mMd				~0.2 s	α (99.99%)	²⁴³Es
^247mMd				~0.2 s	SF (10⁻⁴%)	(various)
²⁴⁸Md	101	147	248.08282(26)#	7(3) s	β⁺ (80%)	²⁴⁸Fm
					α (20%)	²⁴⁴Es
					β⁺, SF (.05%)	(various)
²⁴⁹Md	101	148	249.08291(22)#	24(4) s	α (60%)	²⁴⁵Es	(7/2−)
²⁴⁹Md	101	148	249.08291(22)#	24(4) s	β⁺ (40%)	²⁴⁹Fm	(7/2−)
^249mMd	100(100)# keV			1.9(9) s			(1/2−)
²⁵⁰Md	101	149	250.08442(32)#	52(6) s	β⁺ (93%)	²⁵⁰Fm
					α (7%)	²⁴⁶Es
					β⁺, SF (.02%)	(various)
²⁵¹Md	101	150	251.084774(20)	4.0(5) min	β⁺ (90%)	²⁵¹Fm	7/2−#
²⁵¹Md	101	150	251.084774(20)	4.0(5) min	α (10%)	²⁴⁷Es	7/2−#
²⁵²Md	101	151	252.08643(14)#	2.3(8) min	β⁺ (50%)	²⁵²Fm
²⁵²Md	101	151	252.08643(14)#	2.3(8) min	α (50%)	²⁴⁸Es
²⁵³Md	101	152	253.08714(3)#	12(8) min [6(+12−3) min]	β⁺	²⁵³Fm	7/2−#
²⁵³Md	101	152	253.08714(3)#	12(8) min [6(+12−3) min]	α	²⁴⁹Es	7/2−#
²⁵⁴Md	101	153	254.08959(11)#	10(3) min	β⁺	²⁵⁴Fm	(0−)
²⁵⁴Md	101	153	254.08959(11)#	10(3) min	α (rare)	²⁵⁰Es	(0−)
^254mMd	50(100)# keV			28(8) min	β⁺	²⁵⁴Fm	(3−)
^254mMd	50(100)# keV			28(8) min	α (rare)	²⁵⁰Es	(3−)
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−)
²⁵⁶Md	101	155	256.09389(13)#	77(2) min	α (11%)	²⁵²Es	(1−)
²⁵⁷Md	101	156	257.0955424(29)	5.52(5) h	EC (84.8%)	²⁵⁷Fm	(7/2−)
					α (15.2%)	²⁵³Es
					SF (1%)	(various)
²⁵⁸Md	101	157	258.098431(5)	51.5(3) d	α (99.99%)	²⁵⁴Es	(8−)#
					β⁻ (.0015%)	²⁵⁸No
					β⁺ (.0015%)	²⁵⁸Fm
^258mMd	0(200)# keV			57.0(9) min	EC (70%)	²⁵⁸Fm	1−#
					SF (20%)	(various)
					β⁻ (10%)	²⁵⁸No
					α (1.2%)	²⁵⁴Es
²⁵⁹Md^{[n 7]}	101	158	259.10051(22)#	1.60(6) h	SF (98.7%)	(various)	7/2−#
²⁵⁹Md^{[n 7]}	101	158	259.10051(22)#	1.60(6) h	α (1.3%)	²⁵⁵Es	7/2−#
²⁶⁰Md	101	159	260.10365(34)#	27.8(8) d	SF (85%)	(various)
					α (5%)	²⁵⁶Es
					EC (5%)	²⁶⁰Fm
					β⁻ (3.5%)	²⁶⁰No
This table header & footer: view

^ ^mMd – Excited nuclear isomer.
^ ( ) – 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).
^ Modes of decay:

EC: Electron capture

SF: Spontaneous fission
^ ( ) spin value – Indicates spin with weak assignment arguments.
^ ^a ^b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
^ Not directly synthesized, occurs as decay product of ²⁵⁹No

Chronology of isotope discovery[]

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)^[2]
²⁶⁰Md	1989	²⁵⁴Es+¹⁸O, ²²Ne — transfer

References[]

^ Pore, J. L.; Gates, J. M.; Orford, R.; Campbell, C. M.; Clark, R. M.; Crawford, H. L.; Esker, N. E.; Fallon, P.; Gooding, J. A.; Kwarsick, J. T.; Macchiavelli, A. O.; Morse, C.; Rudolph, D.; Såmark-Roth, A.; Santamaria, C.; Shah, R. S.; Stoyer, M. A. (2020). "Identification of the new isotope ²⁴⁴Md" (PDF). Physical Review Letters. 124 (25–26). doi:10.1103/PhysRevLett.124.252502.
^ see nobelium

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.
- 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
Isotopic compositions and standard atomic masses from:
- de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
- Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary. {{cite journal}}: Cite uses deprecated parameter |lay-url= (help)
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.

[1] Md – Excited nuclear isomer.

[2] ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.

[TMS-3] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[4] Modes of decay:

EC: Electron capture

SF: Spontaneous fission

[5] ( ) spin value – Indicates spin with weak assignment arguments.

[TNN-6] # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[8] Not directly synthesized, occurs as decay product of ²⁵⁹No

[Md244-7] Pore, J. L.; Gates, J. M.; Orford, R.; Campbell, C. M.; Clark, R. M.; Crawford, H. L.; Esker, N. E.; Fallon, P.; Gooding, J. A.; Kwarsick, J. T.; Macchiavelli, A. O.; Morse, C.; Rudolph, D.; Såmark-Roth, A.; Santamaria, C.; Shah, R. S.; Stoyer, M. A. (2020). "Identification of the new isotope ²⁴⁴Md" (PDF). Physical Review Letters. 124 (25–26). doi:10.1103/PhysRevLett.124.252502.

[9] see nobelium

[n 1]

[n 2]

[n 3]

[n 4]

[n 5]

[n 6]

[1]

[n 7]

[2]