Uranium-234 has a half-life of 246,000 years. How did we measure that if the technology to do that hasn’t been around that long?

Question

Uranium-234 has a half-life of 246,000 years. How did we measure that if the technology to do that hasn’t been around that long?

In: Chemistry

Answer 1

In 246,000 years, half a sample will decay.

But if you have 492,000 atoms, there’s a good chance that one of them will go *this* year.

In a gram of uranium there’s ~10^21 atoms, and so even though any individual atom is likely to last for a hundred millennia, there will be a detectable rate of decay over a much shorter period of time.

You count how many decay events your Geiger counter picks up in an hour and extrapolate that out.