Tungsten-180

Main isotopes of tungsten

Iso­tope Decay abun­dance half-life mode energy (MeV) pro­duct 180W 0.12% 1.8×1018 y α 2.516 176Hf 181W syn 121.2 d ε 0.188 181Ta 182W 26.50% is stable with 108 neutrons 183W 14.31% is stable with 109 neutrons 184W 30.64% is stable with 110 neutrons 185W syn 75.1 d β− 0.433 185Re 186W 28.43% is stable with 112 neutrons
Standard atomic weight (Ar)	183.84(1)

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 1.8 ± 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:

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).

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