If radioactive elements decay over time, and after turning into other radioactive elements one day turn into a stable element (e.g. Uranium -> Radium -> Radon -> Polonium -> Lead): Does this mean one day there will be no radioactive elements left on earth?

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If radioactive elements decay over time, and after turning into other radioactive elements one day turn into a stable element (e.g. Uranium -> Radium -> Radon -> Polonium -> Lead): Does this mean one day there will be no radioactive elements left on earth?

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7 Answers

Anonymous 0 Comments

Theoretically, yes. Elements higher than iron on the periodic table are only made in supernova events. Realistically, earth would be swallowed by the sun when it turns into a red giant long before.

Anonymous 0 Comments

Interesting fact, there used to be naturally occurring nuclear reactors. Right now I believe U-235 it about .7% of uranium. But a long time ago before a lot of it decayed away, it was around 3%. And we can see geological evidence of uranium masses underground that had rain water flow through them acting as a moderator.

But theoretically it will all decay away at some point. Not sure if Earth will still be around by then though. I am sure someone on here knows though!

Anonymous 0 Comments

Perhaps we could run out of uranium one day, but some radioactive elements like carbon-14 are constantly replenished by cosmic rays, and others like bismuth-209 have long enough half-lives to outlast the Earth by a wide margin.

Anonymous 0 Comments

Eventually, yes, but not on the timescale you’re thinking of.

The earth will be long gone (and absorbed by the sun) before we run out of radioactive elements in the solar system.

Heck, the sun will have likely turned into what… a brown dwarf before then?

Eventually, yes, the universe will run out of radioactive elements. But that’s only when it cools off enough to stop producing stars and therefore stop producing more of those elements.

Anonymous 0 Comments

Not all of them. carbon 14 is created by radiation from the Sun. Basically it is beta decay in reverse, turning N-14 into C14. Without this replenishment we would have run out of C14 long ago.

Anonymous 0 Comments

The simplest way of putting it is yes, all Isotopes will eventually decay. However the Earth will cease to exist *long* before that happens.

Uranium-238 for example has a half life of 4.5 Billion years (the age of the earth today), which means that long after the Earth has been swallowed up by our nearest and dearest Star there will still be roughly half the Uranium-238 there is today.

But that’s not even scratching the surface. Some isotopes, such as Xenon-124 will far outlast even the age of the entire universe as we know it, and will certainly be one of the last remaining known Isotopes to decay with a half life of 1.8×10^22 (~18 Sextillion) years, or roughly 1 Trillion times the age of the universe.

Xe-124 will likely outlast the longest lived celestial bodies like Red Dwarf Stars, and maybe even the evaporation of some black holes.

So we *will* run out eventually, but not for a long while…

Anonymous 0 Comments

Eventually the entire Universe will go cold. This will basically happen when all the radioactive elements have decayed to stable forms.

This will take a very, very, very, *very* long time. Our planet will be long gone before this happens.

After that, pretty much an eternity of cold and dark.

To answer your question: no, because the planet will be gone before all the radioactive elements decay all the way.