An atom with the same number of protons in the nucleus but a different number of neutrons is called an isotope.For example, uranium-238 is an isotope of uranium-235, because it has 3 more neutrons in the nucleus.If we knew the fraction of a radioactive element still remaining in a mineral, it would be a simple matter to calculate its age by the formula To determine the fraction still remaining, we must know both the amount now present and also the amount present when the mineral was formed.

Together with stratigraphic principles, radiometric dating methods are used in geochronology to establish the geological time scale.

Radiometric dating is also used to date archaeological materials, including ancient artifacts.

Different methods of radiometric dating vary in the timescale over which they are accurate and the materials to which they can be applied.

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.

By establishing geological timescales, radiometric dating provides a significant source of information about the ages of fossils and rates of evolutionary change, and it is also used to date archaeological materials, including ancient artifacts.

The different methods of radiometric dating are accurate over different timescales, and they are useful for different materials.

Scientists look at half-life decay rates of radioactive isotopes to estimate when a particular atom might decay.

A useful application of half-lives is radioactive dating.

This has to do with figuring out the age of ancient things.

If you could watch a single atom of a radioactive isotope, U-238, for example, you wouldn’t be able to predict when that particular atom might decay.

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