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Isotopes of lawrencium

Lawrencium (Lr) has no stable isotopes. A standard atomic mass cannot be given.

Lawrencium has also been called eka-lutetium.

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)
²⁵¹Lr	103	148	251.09436(32)#	150# µs
²⁵²Lr	103	149	252.09537(27)#	390(90) ms [0.36(+11-7) s]
²⁵³Lr	103	150	253.09521(24)#	580(70) ms [0.57(+7-6) s]	(7/2-)
^253mLr	30(100)# keV			1.5(3) s [1.5(+3-2) s]	(1/2-)
²⁵⁴Lr	103	151	254.09645(36)#	13(3) s
²⁵⁵Lr	103	152	255.09668(22)#	22(4) s	7/2-#
²⁵⁶Lr	103	153	256.09863(24)#	27(3) s
²⁵⁷Lr	103	154	257.09956(22)#	646(25) ms	9/2+#
²⁵⁸Lr	103	155	258.10181(11)#	4.1(3) s
²⁵⁹Lr	103	156	259.10290(8)#	6.2(3) s	9/2+#
²⁶⁰Lr	103	157	260.10550(12)#	3.0(5) min
²⁶¹Lr	103	158	261.10688(22)#	39(12) min
²⁶²Lr	103	159	262.10963(22)#	~4 h
²⁶³Lr	103	160	263.11129(39)#	5# h
²⁶⁴Lr	103	161	264.11404(47)#	10# h
²⁶⁵Lr	103	162	265.11584(77)#	10# h
²⁶⁶Lr	103	163	266.11931(70)#	1# h

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.