# Explain how half life is used in radioactive dating

Note that after one half-life there are not exactly one-half of the atoms remaining, only approximately, because of the random variation in the process.

Nevertheless, when there are many identical atoms decaying (right boxes), the law of large numbers suggests that it is a very good approximation to say that half of the atoms remain after one half-life.

) is the time required for a quantity to reduce to half its initial value.

For example, if there are 3 radioactive atoms with a half-life of one second, there will not be "1.5 atoms" left after one second.

Instead, the half-life is defined in terms of probability: "Half-life is the time required for exactly half of the entities to decay on average".

After one half-life has elapsed, one half of the atoms of the nuclide in question will have decayed into a "daughter" nuclide, or decay product.

In many cases, the daughter nuclide is radioactive, resulting in a decay chain.

This chain eventually ends with the formation of a stable, nonradioactive daughter nuclide.

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