Why radioative decays is not the same rate?there always remain a residue Why?

Answer 1

The decay is constant for like elements. They are measured in half lives so although the "material" gets infinitesimally smaller, it never is completely gone.

Answer 2

In radioactive decay, the idea of “rate” is a little different than in other situations. Instead of one atom per second (or some such number) decaying into a different state, there’s a certain probability that an atom will decay into a different state. Another way of putting this is to say that, after a certain period of time, there’s a 50-50 chance that the atom will have decayed into another state: this period of time is called the “half-life.”

Radioactive decay lies within the realm of quantum mechanics, which is inherently probabilistic (not deterministic). You can’t say with certainty that a quantum mechanical effect will occur; rather, you can only say that it has a certain probability of taking place.

The best analogy for half-life that I’ve seen goes something like this… Imagine a large group of people, all standing up and each one equipped with a coin to flip. They all flip their coins at the same time—heads, they stay standing, tails they sit down. After the first flip (half-life), about half will end up sitting down. After the second flip, another half will end up seated, leaving only about a quarter of the original group standing. After the third flip, one-eighth of the original number will be standing up. And so forth. Any given person (atom) experiences the same probability of sitting down (decaying) over each given coin flip (half-life). The result is, with a large enough group of people (atoms), you end up with a little bit left over.


Ryan Wyatt
Rose Center for Earth & Space
New York, New York

Answer 3

because I forgot to wash my hands.