Why does a radioactive element not fully decay?

Answer 1

Radioactive decay is a function of quantum mechanical probability. When will something happen? It might happen now, it might happen next week, and it might not happen for a thousand years. Let's do a practical example with a deck of cards. A randomly arranged deck of cards is face down on the table and we're turning up cards. When will the next red card appear? The next club? The next face card? The next queen? Same with radioactive decay. You might see two in a second, and wait an hour for another decay. It's a "crap shoot" in that respect. Odd, huh? But that's the way it is. Note that radioactice decay is a statistically derived characteristic. But we've counted carefully and over a long enough period in each case we've investigated to get a "good" number for the half life of a given radionuclide. Certainly in the case of the exotic elements beyond plutonium we've had to work harder and our numbers are a bit less precise because of the small quantities and short half lives. And there are some "kinks" with measuring the half life of something like bismuth-209. Other than that, we're down with making the measurements and doing so with "good" accuracy. A link is provided.

Answer 2

When radioactive elements decay, they decay mathematically via the concept of a half-life. That means that in a certain amount of time, specific to that element, half of the element will decay. The element will always decay by half, so it will never truly disappear. Think of it as dividing by two. Let's say we have 2 grams of a substance. Divide by two and we have 1 gram. Divide by two again we have 0.5 grams. Divide again we have 0.25. Divide again and we get 0.125. Again and we get 0.0625. We will never reach reach zero. We will get close but never reach it.

When it comes down to it though, even the very last atom of a radioactive isotope will eventually decay. We just can't mathematically model the time at which it will happen.

Answer 3

Because, depending on the isotope in question, many isotopes are relatively stable.

It is not true that radioactive isotopes take a long time to decay, many isotopes decay reasonably quickly at an atomic scale, although due to the density of atoms in any sizeable chunk of material it often takes a considerably longer time for whole radioactive substances to decay.

In addition to that, due to the probabilistic nature of particle physics, the rate of decay can vary, and the amount of decay decreases as time goes on

Hope this Helps

The Intelligent Fool

Answer 4

A radioactive element does not fully decay because the process of decay is random and governed by probability. There is a chance that each individual atom of the element may decay, but it is impossible to predict exactly when each atom will decay. Therefore, some atoms will remain undecayed even after a long period of time.

Answer 5

It's a Question of when the material was formed and the mass thereof. The higher the mass the longer the half-life.

Answer 6

Because some of them have extremely long half-lives. A few, in fact, have half-lives that are longer than the accepted age of the universe.