Mercury-204

Main isotopes of mercury

iso NA half-life DM DE (MeV) DP 194Hg syn 444 y ε 0.040 194Au 195Hg syn 9.9 h ε 1.510 195Au 196Hg 0.15% is stable with 116 neutrons 197Hg syn 64.14 h ε 0.600 197Au 198Hg 10.04% is stable with 118 neutrons 199Hg 16.94% is stable with 119 neutrons 200Hg 23.14% is stable with 120 neutrons 201Hg 13.17% is stable with 121 neutrons 202Hg 29.74% is stable with 122 neutrons 203Hg syn 46.612 d β− 0.492 203Tl 204Hg 6.82% is stable with 124 neutrons
Standard atomic weight (Ar)	200.592(3)

There are seven stable isotopes of mercury (₈₀Hg) with ²⁰²Hg being the most abundant (29.86%). The longest-lived radioisotopes are ¹⁹⁴Hg with a half-life of 444 years, and ²⁰³Hg with a half-life of 46.612 days. Most of the remaining 32 radioisotopes have half-lives that are less than a day. ¹⁹⁹Hg and ²⁰¹Hg are the most often studied NMR-active nuclei, having spins of 1/2 and 3/2 respectively.

Mercury-180, producible from thallium-180, was found in 2010 to be capable of an unusual form of spontaneous fission. The fission products are krypton-80 and ruthenium-100.

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