Isotopes of uranium

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Uranium (U)
Standard atomic mass: 238.02891(3) u
The element has no stable isotopes. However, it has a characteristic terrestrial isotopic composition and thus an atomic mass can be given.

[edit] 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)
²¹⁷U	92	125	217.02437(9)	26(14) ms [16(+21-6) ms]	1/2-#
²¹⁸U	92	126	218.02354(3)	6(5) ms	0+
²¹⁹U	92	127	219.02492(6)	55(25) µs [42(+34-13) µs]	9/2+#
²²⁰U	92	128	220.02472(22)#	60# ns	0+
²²¹U	92	129	221.02640(11)#	700# ns	9/2+#
²²²U	92	130	222.02609(11)#	1.4(7) µs [1.0(+10-4) µs]	0+
²²³U	92	131	223.02774(8)	21(8) µs [18(+10-5) µs]	7/2+#
²²⁴U	92	132	224.027605(27)	940(270) µs	0+
²²⁵U	92	133	225.029391(12)	61(4) ms	5/2+#
²²⁶U	92	134	226.029339(14)	269(6) ms	0+
²²⁷U	92	135	227.031156(18)	1.1(1) min	(3/2+)
²²⁸U	92	136	228.031374(16)	9.1(2) min	0+
²²⁹U	92	137	229.033506(6)	58(3) min	(3/2+)
²³⁰U	92	138	230.033940(5)	20.8 d	0+
²³¹U	92	139	231.036294(3)	4.2(1) d	(5/2)(+#)
²³²U	92	140	232.0371562(24)	68.9(4) a	0+
²³³U	92	141	233.0396352(29)	1.592(2)E+5 a	5/2+
²³⁴U	92	142	234.0409521(20)	2.455(6)E+5 a	0+	[0.000054(5)]	0.000050-0.000059
^234mU	1421.32(10) keV			33.5(20) µs	6-
²³⁵U	92	143	235.0439299(20)	7.04(1)E+8 a	7/2-	[0.007204(6)]	0.007198-0.007207
^235mU	0.0765(4) keV			~26 min	1/2+
²³⁶U	92	144	236.045568(2)	2.342(3)E+7 a	0+
^236m1U	1052.89(19) keV			100(4) ns	(4)-
^236m2U	2750(10) keV			120(2) ns	(0+)
²³⁷U	92	145	237.0487302(20)	6.75(1) d	1/2+
²³⁸U	92	146	238.0507882(20)	4.468(3)E+9 a	0+	[0.992742(10)]	0.992739-0.992752
^238mU	2557.9(5) keV			280(6) ns	0+
²³⁹U	92	147	239.0542933(21)	23.45(2) min	5/2+
^239m1U	20(20)# keV			>250 ns	(5/2+)
^239m2U	133.7990(10) keV			780(40) ns	1/2+
²⁴⁰U	92	148	240.056592(6)	14.1(1) h	0+
²⁴¹U	92	149	241.06033(32)#	5# min	7/2+#
²⁴²U	92	150	242.06293(22)#	16.8(5) min	0+

[edit] Notes

Evaluated isotopic composition is for most but not all commercial samples.
The precision of the isotope abundances and atomic mass is limited through variations. The given ranges should be applicable to any normal terrestrial material.
Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
Commercially available materials may have been subjected to an undisclosed or inadvertent isotopic fractionation. Substantial deviations from the given mass and composition can occur.
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.

[edit] References

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.