Isotopes of mendelevium

Isotopes of mendelevium: Mendelevium (Md) is an artificial element, and thus a standard atomic mass 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 18 known radioisotopes, ranging in atomic mass from ²⁴⁵Md to ²⁶²Md, 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 58.0 minutes.

Table

nuclide
symbol Z(p) N(n)
isotopic mass (u)
half-life decay
mode(s)^[1]^{[n 1]} daughter
isotope(s) nuclear
spin

excitation energy

²⁴⁵Md 101 144 245.08083(35)# 0.90(25) ms SF (various) (1/2-)#

α (rare) ²⁴¹Es

^245mMd 200(100)# keV 400(200) ms
[0.35(+23-16) s] α ²⁴¹Es (7/2+)

β⁺ (rare) ²⁴⁵Fm

²⁴⁶Md 101 145 246.08189(35)# 1.0(4) s α ²⁴²Es

β⁺ (rare) ²⁴⁶Fm

²⁴⁷Md 101 146 247.08164(35)# 1.12(22) s SF (various) 1/2-#

α (rare) ²⁴³Es

^247mMd ~0.2 s α (99.99%) ²⁴³Es

SF (10⁻⁴%) (various)

²⁴⁸Md 101 147 248.08282(26)# 7(3) s β⁺ (80%) ²⁴⁸Fm

α (20%) ²⁴⁴Es

β⁺, SF (.05%) (various)

²⁴⁹Md 101 148 249.08301(24)# 24(4) s α (60%) ²⁴⁵Es (7/2-)

β⁺ (40%) ²⁴⁹Fm

^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 101 150 251.08484(22)# 4.0(5) min β⁺ (90%) ²⁵¹Fm 7/2-#

α (10%) ²⁴⁷Es

²⁵²Md 101 151 252.08656(21)# 2.3(8) min β⁺ (50%) ²⁵²Fm

α (50%) ²⁴⁸Es

²⁵³Md 101 152 253.08728(22)# 12(8) min
[6(+12-3) min] β⁺ ²⁵³Fm 7/2-#

α ²⁴⁹Es

²⁵⁴Md 101 153 254.08966(11)# 10(3) min β⁺ ²⁵⁴Fm (0-)

α (rare) ²⁵⁰Es

^254mMd 50(100)# keV 28(8) min β⁺ ²⁵⁴Fm (3-)

α (rare) ²⁵⁰Es

²⁵⁵Md 101 154 255.091083(7) 27(2) min β⁺ (92%) ²⁵⁵Fm (7/2-)

α (8%) ²⁵¹Es

SF (.15%) (various)

²⁵⁶Md 101 155 256.09406(6) 77(2) min β⁺ (89%) ²⁵⁶Fm (1-)

α (11%) ²⁵²Es

²⁵⁷Md 101 156 257.095541(3) 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 101 158 259.10051(22)# 1.60(6) h SF (98.7%) (various) 7/2-#

α (1.3%) ²⁵⁵Es

²⁶⁰Md 101 159 260.10365(34)# 27.8(8) d SF (85%) (various)

α (5%) ²⁵⁶Es

EC (5%) ²⁶⁰Fm

β^- (3.5%) ²⁶⁰No

²⁶¹Md 101 160 261.10572(70)# 40# min 7/2-#

²⁶²Md 101 161 262.10887(63)# 3# min

^ Abbreviations:
EC: Electron capture
IT: Isomeric transition
SF: Spontaneous fission

Notes

Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.

Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

References

^ http://www.nucleonica.net/unc.aspx

Isotope masses from:

G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (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. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf.

Isotopic compositions and standard atomic masses from:

J. R. de Laeter, J. K. Böhlke, P. De Bièvre, H. Hidaka, H. S. Peiser, K. J. R. Rosman and P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry 75 (6): 683–800. doi:10.1351/pac200375060683. http://www.iupac.org/publications/pac/75/6/0683/pdf/.

M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry 78 (11): 2051–2066. doi:10.1351/pac200678112051. http://iupac.org/publications/pac/78/11/2051/pdf/. Lay summary.

Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.

G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (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. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf.

National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/. Retrieved September 2005.

N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0849304859.

Isotopes of fermium Isotopes of mendelevium Isotopes of nobelium

Index to isotope pages · Table of nuclides

Categories:
Mendelevium
Isotopes of mendelevium
Lists of isotopes by element

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)^[1]^{[n 1]}	daughter isotope(s)	nuclear spin
excitation energy
²⁴⁵Md	101	144	245.08083(35)#	0.90(25) ms	SF	(various)	(1/2-)#
α (rare)	²⁴¹Es
^245mMd	200(100)# keV	400(200) ms [0.35(+23-16) s]	α	²⁴¹Es	(7/2+)
β⁺ (rare)	²⁴⁵Fm
²⁴⁶Md	101	145	246.08189(35)#	1.0(4) s	α	²⁴²Es
β⁺ (rare)	²⁴⁶Fm
²⁴⁷Md	101	146	247.08164(35)#	1.12(22) s	SF	(various)	1/2-#
α (rare)	²⁴³Es
^247mMd		~0.2 s	α (99.99%)	²⁴³Es
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	249.08301(24)#	24(4) s	α (60%)	²⁴⁵Es	(7/2-)
β⁺ (40%)	²⁴⁹Fm
^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	251.08484(22)#	4.0(5) min	β⁺ (90%)	²⁵¹Fm	7/2-#
α (10%)	²⁴⁷Es
²⁵²Md	101	151	252.08656(21)#	2.3(8) min	β⁺ (50%)	²⁵²Fm
α (50%)	²⁴⁸Es
²⁵³Md	101	152	253.08728(22)#	12(8) min [6(+12-3) min]	β⁺	²⁵³Fm	7/2-#
α	²⁴⁹Es
²⁵⁴Md	101	153	254.08966(11)#	10(3) min	β⁺	²⁵⁴Fm	(0-)
α (rare)	²⁵⁰Es
^254mMd	50(100)# keV	28(8) min	β⁺	²⁵⁴Fm	(3-)
α (rare)	²⁵⁰Es
²⁵⁵Md	101	154	255.091083(7)	27(2) min	β⁺ (92%)	²⁵⁵Fm	(7/2-)
α (8%)	²⁵¹Es
SF (.15%)	(various)
²⁵⁶Md	101	155	256.09406(6)	77(2) min	β⁺ (89%)	²⁵⁶Fm	(1-)
α (11%)	²⁵²Es
²⁵⁷Md	101	156	257.095541(3)	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	101	158	259.10051(22)#	1.60(6) h	SF (98.7%)	(various)	7/2-#
α (1.3%)	²⁵⁵Es
²⁶⁰Md	101	159	260.10365(34)#	27.8(8) d	SF (85%)	(various)
α (5%)	²⁵⁶Es
EC (5%)	²⁶⁰Fm
β^- (3.5%)	²⁶⁰No
²⁶¹Md	101	160	261.10572(70)#	40# min			7/2-#
²⁶²Md	101	161	262.10887(63)#	3# min

Isotopes of fermium	Isotopes of mendelevium	Isotopes of nobelium
Index to isotope pages · Table of nuclides

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