Isotopes of mendelevium

Isotopes of mendelevium (₁₀₁Md)
α	252Es
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)^[2] ^{[n 2]}^{[n 3]}	Half-life^[1]	Decay mode^[1] ^{[n 4]}	Daughter isotope	Spin and parity^[1] ^{[n 5]}^{[n 6]}
Nuclide ^{[n 1]}	Excitation energy^{[n 6]}			Half-life^[1]	Decay mode^[1] ^{[n 4]}	Daughter isotope	Spin and parity^[1] ^{[n 5]}^{[n 6]}
²⁴⁴Md^{[n 7]}	101	143	244.08116(40)#	0.36(14) s	α	²⁴⁰Es	3+#
²⁴⁴Md^{[n 7]}	101	143	244.08116(40)#	0.36(14) s	β⁺, SF (<14%)	(various)	3+#
^244mMd^{[n 7]}	200(150)# keV			~9 μs	IT	²⁴⁴Md	7+#
²⁴⁵Md	101	144	245.08086(28)#	0.38(10) s	α	²⁴¹Es	(7/2−)
^245mMd^{[n 8]}	100(100)# keV			0.90(25) ms	SF	(various)	1/2−#
²⁴⁶Md	101	145	246.08171(28)#	0.92(18) s	α	²⁴²Es	1−#
^246mMd^{[n 8]}	60(60) keV			4.4(8) s	β⁺ (~67%)	²⁴⁶Fm	4−#
					α (<23%)	²⁴²Es
					β⁺, SF (>10%)	(various)
²⁴⁷Md^[4]	101	146	247.08152(22)#	1.20(12) s	α (99.14%)	²⁴³Es	(7/2−)
²⁴⁷Md^[4]	101	146	247.08152(22)#	1.20(12) s	SF (0.86%)	(various)	(7/2−)
^247mMd	153 keV			0.23(3) s	α (80%)	²⁴³Es	(1/2−)
^247mMd	153 keV			0.23(3) s	SF (20%)	(various)	(1/2−)
²⁴⁸Md	101	147	248.08261(20)#	7(3) s	β⁺ (80%)	²⁴⁸Fm
					α (20%)	²⁴⁴Es
					β⁺, SF (<0.05%)	(various)
²⁴⁹Md	101	148	249.08286(18)	25.6(9) s	α (75%)	²⁴⁵Es	(7/2−)
²⁴⁹Md	101	148	249.08286(18)	25.6(9) s	β⁺ (25%)	²⁴⁹Fm	(7/2−)
^249mMd^{[n 8]}	100(100)# keV			1.9(9) s	α	²⁴⁵Es	(1/2−)
²⁵⁰Md	101	149	250.084165(98)	54(4) s	β⁺ (93.0%)	²⁵⁰Fm	2−#
					α (7.0%)	²⁴⁶Es
					β⁺, SF (0.026%)	(various)
^250mMd	120(40) keV			42.4(45) s	α	²⁴⁶Es	7+#
²⁵¹Md	101	150	251.084774(20)	4.21(23) min	β⁺ (90%)	²⁵¹Fm	(7/2−)
²⁵¹Md	101	150	251.084774(20)	4.21(23) min	α (10%)	²⁴⁷Es	(7/2−)
^251mMd	53(8) keV			20# s			(1/2−)
²⁵²Md	101	151	252.086385(98)	2.3(8) min	β⁺	²⁵²Fm	1+#
²⁵³Md	101	152	253.087143(34)#	12(8) min	β⁺ (~99.3%)	²⁵³Fm	(7/2−)
²⁵³Md	101	152	253.087143(34)#	12(8) min	α (~0.7%)	²⁴⁹Es	(7/2−)
^253mMd	60(30) keV			1# min			(1/2−)
²⁵⁴Md	101	153	254.08959(11)#	10(3) min	β⁺	²⁵⁴Fm	0−#
^254mMd^{[n 8]}	50(100)# keV			28(8) min	β⁺	²⁵⁴Fm	3−#
²⁵⁵Md	101	154	255.0910817(60)	27(2) min	β⁺ (93%)	²⁵⁵Fm	7/2−
²⁵⁵Md	101	154	255.0910817(60)	27(2) min	α (7%)	²⁵¹Es	7/2−
²⁵⁶Md	101	155	256.09389(13)#	77.7(18) min	β⁺ (90.8%)	²⁵⁶Fm	(1−)
					α (9.2%)	²⁵²Es
					SF (<3%)	(various)
²⁵⁷Md	101	156	257.0955373(17)	5.52(5) h	EC (85%)	²⁵⁷Fm	(7/2−)
²⁵⁷Md	101	156	257.0955373(17)	5.52(5) h	α (15%)	²⁵³Es	(7/2−)
²⁵⁸Md	101	157	258.0984336(37)	51.59(29) d	α	²⁵⁴Es	(8−)#
					β⁻ (<0.0015%)	²⁵⁸No
					β⁺ (<0.0015%)	²⁵⁸Fm
^258mMd^{[n 8]}	0(200)# keV			57.0(9) min	EC (85%)	²⁵⁸Fm	1−#
					SF (<15%)	(various)
					α (<1.2%)	²⁵⁴Es
²⁵⁹Md^{[n 9]}	101	158	259.10045(11)#	1.60(6) h	SF	(various)	7/2−#
²⁶⁰Md	101	159	260.10365(34)#	27.8(8) d	SF	(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).
^ ^a ^b Discovery of this isotope is disputed due to conflicting data.^[3]
^ ^a ^b ^c ^d ^e Order of ground state and isomer is uncertain.
^ 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)^[5]
²⁶⁰Md	1989	²⁵⁴Es+¹⁸O, ²²Ne — transfer

References

^ ^a ^b ^c ^d 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.
^ 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.
^ Heßberger, F. P.; Block, M.; Düllmann, Ch. E.; Yakushev, A.; Leino, M.; Uusitalo, J. (3 May 2021). "Some Remarks on the Discovery of Md 244". Physical Review Letters. 126 (18). doi:10.1103/PhysRevLett.126.182501.
^ 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.
^ 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. S2CID 250839471.
- 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
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. S2CID 94982856.

[2] Md – Excited nuclear isomer.

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

[TMS-5] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[6] Modes of decay:

EC: Electron capture

SF: Spontaneous fission

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

[TNN-8] # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[244md-10] Discovery of this isotope is disputed due to conflicting data.^[3]

[order-11] Order of ground state and isomer is uncertain.

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

[NUBASE2020-1] 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.

[AME2020_II-3] 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.

[9] Heßberger, F. P.; Block, M.; Düllmann, Ch. E.; Yakushev, A.; Leino, M.; Uusitalo, J. (3 May 2021). "Some Remarks on the Discovery of Md 244". Physical Review Letters. 126 (18). doi:10.1103/PhysRevLett.126.182501.

[12] 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.

[14] see nobelium

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