Exactly the same treatment can be applied to **radioactive** **decay**.However, now the "thin slice" is an interval of time, and the dependent variable is the number of *radioactive* atoms present, N(t). If we have a sample of atoms, and we consider a time interval short enough that the population of atoms hasn't changed significantly through *decay*, then the proportion of atoms *decaying* in our short time interval will be proportional to the length of the interval.It then takes the same amount of time for half the remaining **radioactive** atoms to **decay**, and the same amount of time for half of those remaining **radioactive** atoms to **decay**, and so on. The amount of time it takes for one-half of a sample to **decay** is called the half-life of the isotope, and it’s given the symbol: It’s important to realize that the half-life **decay** of **radioactive** isotopes is not linear.For example, you can’t find the remaining amount of an isotope as 7.5 half-lives by finding the midpoint between 7 and 8 half-lives.

It is based on measurement of the product of the *radioactive* *decay* of an isotope of potassium (K) into argon (Ar).

However, radioisotope **dating** may not work so well in the future.

Anything that dies after the 1940s, when Nuclear bombs, nuclear reactors and open-air nuclear tests started changing things, will be harder to date precisely.

It might take a millisecond, or it might take a century. But if you have a large enough sample, a pattern begins to emerge.

It takes a certain amount of time for half the atoms in a sample to *decay*.