Radiometric dating and radiocarbon dating

The methods work because radioactive elements are unstable, and they are always trying to move to a more stable state. This process by which an unstable atomic nucleus loses energy by releasing radiation is called radioactive decay.

The thing that makes this decay process so valuable for determining the age of an object is that each radioactive isotope decays at its own fixed rate, which is expressed in terms of its half-life.

Carbon-14 is continually being created in the atmosphere due to the action of cosmic rays on nitrogen in the air.

radiometric dating and radiocarbon dating-60

With radiocarbon dating, the amount of the radioactive isotope carbon-14 is measured.

Compared to some of the other radioactive isotopes we have discussed, carbon-14's half-life of 5,730 years is considerably shorter, as it decays into nitrogen-14.

With rubidium-strontium dating, we see that rubidium-87 decays into strontium-87 with a half-life of 50 billion years.

By anyone's standards, 50 billion years is a long time.

These two uranium isotopes decay at different rates. The half-life of the uranium-238 to lead-206 is 4.47 billion years.

The uranium-235 to lead-207 decay series is marked by a half-life of 704 million years.

However, rocks and other objects in nature do not give off such obvious clues about how long they have been around.

So, we rely on radiometric dating to calculate their ages.

When the isotope is halfway to that point, it has reached its half-life.

There are different methods of radiometric dating that will vary due to the type of material that is being dated.

So, if you know the radioactive isotope found in a substance and the isotope's half-life, you can calculate the age of the substance. Well, a simple explanation is that it is the time required for a quantity to fall to half of its starting value.

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