Isotopes of silver

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Naturally occurring silver (₄₇Ag) is composed of the two stable isotopes ¹⁰⁷Ag and ¹⁰⁹Ag in almost equal proportions, with ¹⁰⁷Ag being slightly more abundant (51.839% natural abundance). Notably, silver is the only element with all stable istopes having nuclear spins of 1/2. Thus both ¹⁰⁷Ag and ¹⁰⁹Ag nuclei produce narrow lines in nuclear magnetic resonance spectra.^[4]

40 radioisotopes have been characterized with the most stable being ¹⁰⁵Ag with a half-life of 41.29 days, ¹¹¹Ag with a half-life of 7.43 days, and ¹¹²Ag with a half-life of 3.13 hours.

All of the remaining radioactive isotopes have half-lives that are less than an hour, and the majority of these have half-lives that are less than 3 minutes. This element has numerous meta states, with the most stable being ^108mAg (half-life 439 years), ^110mAg (half-life 249.86 days) and ^106mAg (half-life 8.28 days).

Isotopes of silver range in atomic weight from 91.960 u (⁹²Ag) to 132.969 u (¹³³Ag). The primary decay mode before the most abundant stable isotope, ¹⁰⁷Ag, is electron capture and the primary mode after is beta decay. The primary decay products before ¹⁰⁷Ag are palladium (element 46) isotopes and the primary products after are cadmium (element 48) isotopes.

The palladium isotope ¹⁰⁷Pd decays by beta emission to ¹⁰⁷Ag with a half-life of 6.5 million years. Iron meteorites are the only objects with a high enough palladium/silver ratio to yield measurable variations in ¹⁰⁷Ag abundance. Radiogenic ¹⁰⁷Ag was first discovered in the Santa Clara meteorite in 1978.

The discoverers suggest that the coalescence and differentiation of iron-cored small planets may have occurred 10 million years after a nucleosynthetic event. ¹⁰⁷Pd versus ¹⁰⁷Ag correlations observed in bodies, which have clearly been melted since the accretion of the Solar System, must reflect the presence of live short-lived nuclides in the early Solar System.