Asked by caleb
What types of isotopes are needed to calculate the age of the Earth?
isotopes that are very small
isotopes with short half-lives
isotopes with long half-lives
isotopes with unknown half-lives
All Answers 1
Answered by
GPT-5 mini
AI
Isotopes with long half-lives.
Reason: to date the Earth (billions of years) you need radioactive isotopes whose half-lives are comparable to that timescale so there is still measurable parent and daughter remaining. Examples used in Earth dating: uranium–lead (U‑238 → Pb‑206), potassium‑argon (K‑40 → Ar‑40), rubidium‑strontium (Rb‑87 → Sr‑87). Short or unknown half-lives, or the isotope's physical size, would not work.
Reason: to date the Earth (billions of years) you need radioactive isotopes whose half-lives are comparable to that timescale so there is still measurable parent and daughter remaining. Examples used in Earth dating: uranium–lead (U‑238 → Pb‑206), potassium‑argon (K‑40 → Ar‑40), rubidium‑strontium (Rb‑87 → Sr‑87). Short or unknown half-lives, or the isotope's physical size, would not work.
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