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.
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.
Since the potassium-argon dating methods clearly appear to be unreliable, why should any rational person trust them to provide accurate dates for rocks?
In the early 1950s, scientists established theories for using the decay of radioactive potassium (Ar) as a clock for dating certain types of rocks.
Called “noble” because it rarely bonds with other elements, argon (Ar) is one of the six noble gases.
The others include helium (He), neon (Ne), krypton (Kr), xenon (Xe), and radon (Rn).
measurement, measuring, mensuration, measure - the act or process of assigning numbers to phenomena according to a rule; "the measurements were carefully done"; "his mental measurings proved remarkably accurate" techniques to precisely measure the age of the eruptions of the Kalkarindji volcanic province where lavas covered an area of more than 2 million square kilometers in the Northern Territory and Western Australia.
Figure 1 schematically illustrates these three processes.
We are told that these methods are accurate to a few percent, and that there are many different methods.
We are told that of all the radiometric dates that are measured, only a few percent are anomalous.
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.
How radiometric dating works in general Why methods in general are inaccurate Why K-Ar dating is inaccurate The branching ratio problem How Errors Can Account for the Observed Dates Why older dates would be found lower in the geologic column especially for K-Ar dating Do different methods agree with each other on the geologic column?
Different methods of radiometric dating can be used to estimate the age of a variety of natural and even man-made materials.
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.
When a creature dies, it ceases to consume more radiocarbon while the C-14 already in its body continues to decay back into nitrogen.
Radioactive dating methods—many of which are quite elaborate—have numerous physical condition requirements that cannot realistically remain unaffected over millions and perhaps billions of years.
Learn about half-life and how it is used in different dating methods, such as uranium-lead dating and radiocarbon dating, in this video lesson. As we age, our hair turns gray, our skin wrinkles and our gait slows.
However, rocks and other objects in nature do not give off such obvious clues about how long they have been around.