Isotopes of tungsten

Naturally occurring tungsten (₇₄W) 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 (1.59±0.05)×10¹⁸ years.^[1] On average, two alpha decays of ¹⁸⁰W occur per gram of natural tungsten per year, so for most practical purposes, ¹⁸⁰W can be considered stable. Theoretically, all five naturally occurring isotopes of tungsten can decay into isotopes of hafnium (element 72) by alpha emission, but only ¹⁸⁰W has been observed to do so. The other naturally occurring isotopes have not been observed to decay (they are observationally stable), 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

Isotopes of tungsten (₇₄W)

Main isotopes Decay abun­dance half-life (t1/2) mode pro­duct 180W 0.120% 1.59×1018 y[1] α 176Hf 181W synth 121.2 d ε 181Ta 182W 26.5% stable 183W 14.3% stable 184W 30.6% stable 185W synth 75.1 d β− 185Re 186W 28.4% stable 188W synth 69.78 d β− 188Re
Standard atomic weight Ar°(W)
	183.84±0.01[2] 183.84±0.01 (abridged)[3]
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Thirty-four artificial radioisotopes of tungsten have been characterized with mass numbers ranging from 156 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 twelve known meta states, the most stable being ^179m1W (t_1/2 6.4 minutes).

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da)[4] [n 2][n 3]	Half-life[5] [n 4][n 5]	Decay mode[5] [n 6]	Daughter isotope [n 7][n 8]	Spin and parity[5] [n 9][n 5]	Natural abundance (mole fraction)
	Excitation energy							Normal proportion[5]	Range of variation
156W[6]	74	82		157+57 −34 ms	β+	156Ta	0+
157W[7]	74	83	156.97886(43)#	275(40) ms	β+	157Ta	(7/2−)
158W	74	84	157.97457(32)#	1.43(18) ms	α	154Hf	0+
158mW	1889(8) keV			143(19) μs	α	154Hf	(8+)
159W	74	85	158.97270(32)#	8.2(7) ms	α (82%)	155Hf	7/2−#
160W	74	86	159.96851(16)	90(5) ms	α (87%)	156Hf	0+
					β+ (13%)	160Ta
161W	74	87	160.96725(22)#	409(16) ms	α (73%)	157Hf	7/2−#
					β+ (27%)	161Ta
162W	74	88	161.963500(19)	1.19(12) s	β+ (54.8%)	162Ta	0+
					α (45.2%)	158Hf
163W	74	89	162.962524(63)	2.63(9) s	β+ (86%)	163Ta	7/2−
					α (14%)	159Hf
163mW	480.3(7) keV			154(3) ns	IT	163W	13/2+
164W	74	90	163.958952(10)	6.3(2) s	β+ (96.2%)	164Ta	0+
					α (3.8%)	160Hf
165W	74	91	164.958281(28)	5.1(5) s	β+	165Ta	(5/2−)
166W	74	92	165.955032(10)	19.2(6) s	β+ (99.97%)	166Ta	0+
					α (0.035%)	162Hf
167W	74	93	166.954811(20)	19.9(5) s	β+ (99.96%)	167Ta	(5/2−)
					α (0.04%)	163Hf
168W	74	94	167.951805(14)	50.9(19) s	β+ (99.97%)	168Ta	0+
					α (0.032%)	164Hf
169W	74	95	168.951779(17)	74(6) s	β+	169Ta	5/2−#
170W	74	96	169.949231(14)	2.42(4) min	β+(99%)	170Ta	0+
171W	74	97	170.949451(30)	2.38(4) min	β+	171Ta	(5/2−)
172W	74	98	171.947292(30)	6.6(9) min	β+	172Ta	0+
173W	74	99	172.947689(30)	7.6(2) min	β+	173Ta	5/2−
174W	74	100	173.946079(30)	33.2(21) min	β+	174Ta	0+
174m1W	2267.8(4) keV			158(3) ns	IT	174W	8−
174m2W	3515.6(4) keV			128(8) ns	IT	174W	12+
175W	74	101	174.946717(30)	35.2(6) min	β+	175Ta	(1/2−)
175mW	234.96(15) keV			216(6) ns	IT	175W	(7/2+)
176W	74	102	175.945634(30)	2.5(1) h	EC	176Ta	0+
177W	74	103	176.946643(30)	132.4(20) min	β+	177Ta	1/2−
178W	74	104	177.945886(16)	21.6(3) d	EC	178Ta	0+
178mW	6572.7(3) keV			220(10) ns	IT	178W	25+
179W	74	105	178.947079(16)	37.05(16) min	β+	179Ta	7/2−
179m1W	221.91(3) keV			6.40(7) min	IT (99.71%)	179W	1/2−
					β+ (0.29%)	179Ta
179m2W	1631.90(8) keV			390(30) ns	IT	179W	21/2+
179m3W	3348.41(14) keV			750(80) ns	IT	179W	35/2−
180W[n 10]	74	106	179.9467133(15)	1.59(5)×1018 y[1]	α	176Hf	0+	0.0012(1)
180m1W	1529.05(4) keV			5.47(9) ms	IT	180W	8−
180m2W	3264.7(3) keV			2.33(19) μs	IT	180W	14−
181W	74	107	180.9482187(16)	120.956(19) d	EC	181Ta	9/2+
181m1W	365.55(13) keV			14.59(15) μs	IT	181W	5/2−
181m2W	1653.0(3) keV			200(13) ns	IT	181W	21/2+
182W	74	108	181.94820564(80)	Observationally Stable[n 11]			0+	0.2650(16)
182mW	2230.65(14) keV			1.3(1) μs	IT	182W	10+
183W	74	109	182.95022442(80)	Observationally Stable[n 12]			1/2−	0.1431(4)
183mW	309.492(4) keV			5.30(8) s	IT	183W	11/2+
184W	74	110	183.95093318(79)	Observationally Stable[n 13]			0+	0.3064(2)
184m1W	1284.997(8) keV			8.33(18) μs	IT	184W	5−
184m2W	4127.7(5) keV			188(38) ns	IT	184W	(14+)
185W	74	111	184.95342121(79)	75.1(3) d	β−	185Re	3/2−
185mW	197.383(23) keV			1.597(4) min	IT	185W	11/2+
186W	74	112	185.9543651(13)	Observationally Stable[n 14]			0+	0.2843(19)
186m1W	1517.2(6) keV			18(1) μs	IT	186W	7−
186m2W	3542.8(21) keV			2.0(2) s	IT	186W	16+
187W	74	113	186.9571612(13)	23.809(25) h	β−	187Re	3/2−
187mW	410.06(4) keV			1.54(13) μs[8]	IT	187W	11/2+
188W	74	114	187.9584883(33)	69.77(5) d	β−	188Re	0+
188mW	1926.7(8) keV			109.5(35) ns	IT	188W	8−
189W	74	115	188.96156(22)#	11.6(2) min	β−	189Re	9/2−#
190W	74	116	189.963104(38)	30.0(15) min	β−	190Re	0+
190m1W	1743.6(10) keV			111(17) ns	IT	190W	8+
190m2W	1840.6(14) keV			166(6) μs	IT	190W	10−
191W	74	117	190.966531(45)	14# s [>300 ns]			3/2−#
191mW	235(10)# keV			340(14) ns	IT	191W	9/2−#
192W	74	118	191.96820(22)#	40# s [>300 ns]			0+
193W	74	119	192.97188(22)#	30# s [>300 ns]			1/2−#
194W	74	120	193.97380(32)#	20# s [>300 ns]			0+
195W	74	121	194.97774(32)#	30# s [>160 ns]			3/2−#
196W	74	122	195.97988(43)#	25# s [>300 ns]			0+
197W	74	123	196.98404(43)#	1# s [>300 ns]			5/2−#
This table header & footer: view

1. ^mW – Excited nuclear isomer.
2. ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
3. # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
4. Bold half-life – nearly stable, half-life longer than age of universe.
5. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
6. Modes of decay:

   α:	Alpha decay
   β+:	Positron emission
   EC:	Electron capture
   β−:	Beta decay
   IT:	Isomeric transition

7. Bold italics symbol as daughter – Daughter product is nearly stable.
8. Bold symbol as daughter – Daughter product is stable.
9. ( ) spin value – Indicates spin with weak assignment arguments.
10. Primordial radionuclide
11. Believed to undergo α decay to ¹⁷⁸Hf with a half-life over 7.7×10²¹ y
12. Believed to undergo α decay to ¹⁷⁹Hf with a half-life over 6.70×10²⁰ y
13. Believed to undergo α decay to ¹⁸⁰Hf with a half-life over 8.9×10²¹ y
14. Believed to undergo α decay to ¹⁸²Hf or β⁻β⁻ decay to ¹⁸⁶Os with a half-life over 4.1×10¹⁸ y