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Why are carbon-14 and radon-222 still found on Earth despite their relatively short half-lives?
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isotope
An overview of isotopes.
Carbon-14 and radon-222 are still found on Earth because they are continually replenished by natural processes, despite their relatively short half-lives.1
- Carbon-14: This isotope is formed in the atmosphere through the interaction of cosmic rays with nitrogen atoms. This constant production balances its rate of radioactive decay, maintaining a steady-state concentration in the environment.21
- Radon-222: This gas is produced as an intermediary step in the decay chain of uranium. Because uranium is present in Earth's crust, it continuously generates radium, which in turn decays into radon-222.34
Without these ongoing replenishment mechanisms, these isotopes would have long since vanished from the planet.1