Isotopes of mendelevium

Mendelevium (Md) has no stable isotopes. A standard atomic mass cannot be given.

Mendelevium has also been called eka-thulium.

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
nuclide symbol	excitation energy			half-life	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
²⁴⁵Md	101	144	245.08083(35)#	0.90(25) ms	(1/2-)#
^245mMd	200(100)# keV			400(200) ms [0.35(+23-16) s]	(7/2+)
²⁴⁶Md	101	145	246.08189(35)#	1.0(4) s
²⁴⁷Md	101	146	247.08164(35)#	1.12(22) s	1/2-#
^247mMd				~0.2 s
²⁴⁸Md	101	147	248.08282(26)#	7(3) s
²⁴⁹Md	101	148	249.08301(24)#	24(4) s	(7/2-)
^249mMd	100(100)# keV			1.9(9) s	(1/2-)
²⁵⁰Md	101	149	250.08442(32)#	52(6) s
²⁵¹Md	101	150	251.08484(22)#	4.0(5) min	7/2-#
²⁵²Md	101	151	252.08656(21)#	2.3(8) min
²⁵³Md	101	152	253.08728(22)#	12(8) min [6(+12-3) min]	7/2-#
²⁵⁴Md	101	153	254.08966(11)#	10(3) min	(0-)
^254mMd	50(100)# keV			28(8) min	(3-)
²⁵⁵Md	101	154	255.091083(7)	27(2) min	(7/2-)
²⁵⁶Md	101	155	256.09406(6)	77(2) min	(1-)
²⁵⁷Md	101	156	257.095541(3)	5.52(5) h	(7/2-)
²⁵⁸Md	101	157	258.098431(5)	51.5(3) d	(8-)#
^258mMd	0(200)# keV			57.0(9) min	1-#
²⁵⁹Md	101	158	259.10051(22)#	1.60(6) h	7/2-#
²⁶⁰Md	101	159	260.10365(34)#	31.8(5) d
²⁶¹Md	101	160	261.10572(70)#	40# min	7/2-#
²⁶²Md	101	161	262.10887(63)#	3# min

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.

Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
Isotopic compositions and standard atomic masses from Atomic weights of the elements. Review 2000 (IUPAC Technical Report). Pure Appl. Chem. Vol. 75, No. 6, pp. 683-800, (2003) and Atomic Weights Revised (2005).
Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
- Audi, Bersillon, Blachot, Wapstra. The Nubase2003 evaluation of nuclear and decay properties, Nuc. Phys. A 729, pp. 3-128 (2003).
- National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database (retrieved Sept. 2005).
- David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.

Isotopes of fermium	Isotopes of mendelevium	Isotopes of nobelium
Index to isotope pages

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