Isotopes of einsteinium

Einsteinium (Es) has no stable isotopes. A standard atomic mass cannot be given.

Einsteinium has also been called eka-holmium and athenium.

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)
²⁴⁰Es	99	141	240.06892(43)#	1# s
²⁴¹Es	99	142	241.06854(24)#	10(5) s [8(+6-5) s]	(3/2-)
²⁴²Es	99	143	242.06975(35)#	13.5(25) s
²⁴³Es	99	144	243.06955(25)#	21(2) s	3/2-#
²⁴⁴Es	99	145	244.07088(20)#	37(4) s
²⁴⁵Es	99	146	245.07132(22)#	1.1(1) min	(3/2-)
²⁴⁶Es	99	147	246.07290(24)#	7.7(5) min	4-#
²⁴⁷Es	99	148	247.07366(3)#	4.55(26) min	7/2+#
²⁴⁸Es	99	149	248.07547(6)#	27(5) min	2-#,0+#
²⁴⁹Es	99	150	249.07641(3)#	102.2(6) min	7/2+
²⁵⁰Es	99	151	250.07861(11)#	8.6(1) h	(6+)
^250mEs	200(150)# keV			2.22(5) h	1(-)
²⁵¹Es	99	152	251.079992(7)	33(1) h	(3/2-)
²⁵²Es	99	153	252.08298(5)	471.7(19) d	(5-)
²⁵³Es	99	154	253.0848247(28)	20.47(3) d	7/2+
²⁵⁴Es	99	155	254.088022(5)	275.7(5) d	(7+)
^254mEs	84.2(25) keV			39.3(2) h	2+
²⁵⁵Es	99	156	255.090273(12)	39.8(12) d	(7/2+)
²⁵⁶Es	99	157	256.09360(11)#	25.4(24) min	(1+,0-)
^256mEs	0(100)# keV			7.6 h	(8+)
²⁵⁷Es	99	158	257.09598(44)#	7.7(2) d	7/2+#
²⁵⁸Es	99	159	258.09952(32)#	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 californium	Isotopes of einsteinium	Isotopes of fermium
Index to isotope pages

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