Erbium-168

Main isotopes of erbium

Iso­tope Decay abun­dance half-life mode energy (MeV) pro­duct 160Er syn 28.58 h ε 0.330 160Ho 162Er 0.139% is stable with 94 neutrons 164Er 1.601% is stable with 96 neutrons 165Er syn 10.36 h ε 0.376 165Ho 166Er 33.503% is stable with 98 neutrons 167Er 22.869% is stable with 99 neutrons 168Er 26.978% is stable with 100 neutrons 169Er syn 9.4 d β− 0.351 169Tm 170Er 14.910% is stable with 102 neutrons 171Er syn 7.516 h β− 1.490 171Tm 172Er syn 49.3 h β− 0.891 172Tm
Standard atomic weight (Ar)	7002167259000000000♠167.259(3)

Naturally occurring erbium (₆₈Er) is composed of 6 stable isotopes, with ¹⁶⁶Er being the most abundant (33.503% natural abundance). Thirty radioisotopes have been characterized with between 74 and 108 neutrons, or 142 to 177 nucleons, with the most stable being ¹⁶⁹Er with a half-life of 9.4 days, ¹⁷²Er with a half-life of 49.3 hours, ¹⁶⁰Er with a half-life of 28.58 hours, ¹⁶⁵Er with a half-life of 10.36 hours, and ¹⁷¹Er with a half-life of 7.516 hours. All of the remaining radioactive isotopes have half-lives that are less than 3.5 hours, and the majority of these have half-lives that are less than 4 minutes. This element also has 13 meta states, with the most stable being ^167mEr (t_1/2 2.269 seconds).

The isotopes of erbium range in atomic weight from 141.9723 u (¹⁴²Er) to 176.9541 u (¹⁷⁷Er). The primary decay mode before the most abundant stable isotope, ¹⁶⁶Er, is electron capture, and the primary mode after is beta decay. The primary decay products before ¹⁶⁶Er are holmium isotopes, and the primary products after are thulium isotopes.

...
Wikipedia