Isotopes of tungsten

Naturally occurring tungsten (atomic symbol W) consists of five isotopes. Four are considered stable (¹⁸²W, ¹⁸³W, ¹⁸⁴W, and ¹⁸⁶W) and one is slightly radioactive, ¹⁸⁰W, with an extremely long half-life of 1.8 ± 0.2 Ea (10¹⁸ years). On average, two alpha decays of ¹⁸⁰W occur per gram of natural tungsten per year so for most practical purposes tungsten can be considered stable. Theoretically, all five can decay into isotopes of element 72 (hafnium) by alpha emission, but only ¹⁸⁰W has been observed to do so. The other naturally occurring isotopes have not been observed to decay, and lower bounds for their half lives have been established:

¹⁸²W, t_1/2 > 7.7×10²¹ years

¹⁸³W, t_1/2 > 4.1×10²¹ years

¹⁸⁴W, t_1/2 > 8.9×10²¹ years

¹⁸⁶W, t_1/2 > 8.2×10²¹ years

Thirty-three artificial radioisotopes of tungsten have been characterized with mass numbers ranging from 157 to 194, the most stable of which are ¹⁸¹W with a half-life of 121.2 days, ¹⁸⁵W with a half-life of 75.1 days, ¹⁸⁸W with a half-life of 69.4 days and ¹⁷⁸W with a half-life of 21.6 days. All of the remaining radioactive isotopes have half-lives of less than 24 hours, and most of these have half-lives that are less than 8 minutes. Tungsten also has 11 meta states with mass numbers of 158, 179, with 3, 180, with 2, 183, 185, 186, with 2, and 190, the most stable being ^179m1W (t_1/2 6.4 minutes).

Relative atomic mass: 183.84(1).

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life[n 1]	decay mode(s)[1][n 2]	daughter isotope(s)[n 3]	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
	excitation energy
^158W	74	84	157.97456(54)#	1.37(17) ms	α	^154Hf	0+
^158mW	1889(8) keV			143(19) µs			8+
^159W	74	85	158.97292(43)#	8.2(7) ms	α (82%)	^155Hf	7/2−#
					β^+ (18%)	^159Ta
^160W	74	86	159.96848(22)	90(5) ms	α (87%)	^156Hf	0+
					β^+ (14%)	^160Ta
^161W	74	87	160.96736(21)#	409(16) ms	α (73%)	^157Hf	7/2−#
					β^+ (23%)	^161Ta
^162W	74	88	161.963497(19)	1.36(7) s	β^+ (53%)	^162Ta	0+
					α (47%)	^158Hf
^163W	74	89	162.96252(6)	2.8(2) s	β^+ (59%)	^163Ta	3/2−#
					α (41%)	^159Hf
^164W	74	90	163.958954(13)	6.3(2) s	β^+ (97.4%)	^164Ta	0+
					α (2.6%)	^160Hf
^165W	74	91	164.958280(27)	5.1(5) s	β^+ (99.8%)	^165Ta	3/2−#
					α (.2%)	^161Hf
^166W	74	92	165.955027(11)	19.2(6) s	β^+ (99.96%)	^166Ta	0+
					α (.035%)	^162Hf
^167W	74	93	166.954816(21)	19.9(5) s	β^+ (>99.9%)	^167Ta	3/2−#
					α (<.1%)	^163Hf
^168W	74	94	167.951808(17)	51(2) s	β^+ (99.99%)	^168Ta	0+
					α (.0319%)	^164Hf
^169W	74	95	168.951779(17)	76(6) s	β^+	^169Ta	(5/2−)
^170W	74	96	169.949228(16)	2.42(4) min	β^+(99%)	^170Ta	0+
					α (1%)	^166Hf
^171W	74	97	170.94945(3)	2.38(4) min	β^+	^171Ta	(5/2−)
^172W	74	98	171.94729(3)	6.6(9) min	β^+	^172Ta	0+
^173W	74	99	172.94769(3)	7.6(2) min	β^+	^173Ta	5/2−
^174W	74	100	173.94608(3)	33.2(21) min	β^+	^174Ta	0+
^175W	74	101	174.94672(3)	35.2(6) min	β^+	^175Ta	(1/2−)
^176W	74	102	175.94563(3)	2.5(1) h	EC	^176Ta	0+
^177W	74	103	176.94664(3)	132(2) min	β^+	^177Ta	1/2−
^178W	74	104	177.945876(16)	21.6(3) d	EC	^178Ta	0+
^179W	74	105	178.947070(17)	37.05(16) min	β^+	^179Ta	(7/2)−
^179m1W	221.926(8) keV			6.40(7) min	IT (99.72%)	^179W	(1/2)−
					β^+ (.28%)	^179Ta
^179m2W	1631.90(8) keV			390(30) ns			(21/2+)
^179m3W	3348.45(16) keV			750(80) ns			(35/2−)
^180W[n 4]	74	106	179.946704(4)	1.8(0.2)×10^18 y	α	^176Hf	0+	0.0012(1)
^180m1W	1529.04(3) keV			5.47(9) ms	IT	^180W	8−
^180m2W	3264.56(21) keV			2.33(19) µs			14−
^181W	74	107	180.948197(5)	121.2(2) d	EC	^181Ta	9/2+
^182W	74	108	181.9482042(9)	Observationally Stable [n 5]			0+	0.2650(16)
^183W	74	109	182.9502230(9)	Observationally Stable [n 6]			1/2−	0.1431(4)
^183mW	309.493(3) keV			5.2(3) s	IT	^183W	11/2+
^184W	74	110	183.9509312(9)	Observationally Stable [n 7]			0+	0.3064(2)
^185W	74	111	184.9534193(10)	75.1(3) d	β^−	^185Re	3/2−
^185mW	197.43(5) keV			1.597(4) min	IT	^185W	11/2+
^186W	74	112	185.9543641(19)	Observationally Stable [n 8]			0+	0.2843(19)
^186m1W	1517.2(6) keV			18(1) µs			(7−)
^186m2W	3542.8(21) keV			>3 ms			(16+)
^187W	74	113	186.9571605(19)	23.72(6) h	β^−	^187Re	3/2−
^188W	74	114	187.958489(4)	69.78(5) d	β^−	^188Re	0+
^189W	74	115	188.96191(21)	11.6(3) min	β^−	^189Re	(3/2−)
^190W	74	116	189.96318(18)	30.0(15) min	β^−	^190Re	0+
^190mW	2381(5) keV			<3.1 ms			(10−)
^191W	74	117	190.96660(21)#	20# s [>300 ns]			3/2−#
^192W	74	118	191.96817(64)#	10# s [>300 ns]			0+

1. Bold for isotopes with half-lives longer than the age of the universe (nearly stable)
2. Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
3. Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe)
4. Primordial radionuclide
5. Believed to undergo α decay to ¹⁷⁸Hf with a half-life over 7.7×10²¹ y
6. Believed to undergo α decay to ¹⁷⁹Hf with a half-life over 4.1×10²¹ y
7. Believed to undergo α decay to ¹⁸⁰Hf with a half-life over 8.9×10²¹ y
8. Believed to undergo α decay to ¹⁸²Hf with a half-life over 8.2×10²¹ y

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

1. "Universal Nuclide Chart". nucleonica. (registration required (help)).

• Isotope masses from:
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
• 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; 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.
  • 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. 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; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005. Check date values in: |access-date= (help)
  • 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 978-0-8493-0485-9.