Different radioactive elements have different half-lives. Why are the half-lives different for different elements? How is the half-life of a particular element measured?

Question

Different radioactive elements have different half-lives. Why are the half-lives different for different elements? How is the half-life of a particular element measured?

In: Chemistry

Answer 1

Think of the half life as a measure of how stable the material is.

Imagine I have a row of bottles on a really narrow wall. I might expect that over time some will fall off. The half life would be the average time taken for half the bottles to fall off. If I have an even narrower wall (a less stable material) then I would expect half of the bottles to fall off in less time on average – a shorter half life.

Measuring the half life is just a matter of measuring the number of bottles on the wall at time A, then coming back some time later and measuring the number of bottles at time B. In actual fact it might be easier to watch the wall and record each time a bottle falls off and smashes – a decay event.