Dating rocks using radioactive decay
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.
So, you might say that the 'full-life' of a radioactive isotope ends when it has given off all of its radiation and reaches a point of being non-radioactive.
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.
These differing rates of decay help make uranium-lead dating one of the most reliable methods of radiometric dating because they provide two different decay clocks.
This provides a built-in cross-check to more accurately determine the age of the sample.
Carbon-14 combines with oxygen to create carbon dioxide.So, we start out with two isotopes of uranium that are unstable and radioactive.They release radiation until they eventually become stable isotopes of lead.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.