# Potassium argon dating definition

- Uranium-Lead method - Rubidium-Strontium method - Carbon-14 method – also known as carbon **dating**.

The half-life of carbon-14 is only 5, 730 years so this method is mainly used for **dating** things from the last 50,000 years Here's how it works.

Thus, the ratio of **argon**-40 and **potassium**-40 and radiogenic calcium-40 to **potassium**-40 in a mineral or rock is a measure of the age of the sample.

The calcium-*potassium* age method is seldom used, however, because of the great abundance of nonradiogenic calcium in minerals or rocks, which masks the presence of radiogenic calcium.

The proportion of **potassium** to **argon** suggests how old the object in question is.

An equation used is t = (1/c)Ln(1 (D/P)) Where c is the decay constant D is number of daughter atoms (number decayed) P is the number of parent atoms (number undecayed) t is the age of the object… Carbon *dating* is not useful for *dating* things more than about 50,000 years old.

A volcano explodes over a landscape four million years ago. **Potassium**, naturally occurring in the lava, is made-up of a mixture of radioactive **Potassium**-40 and non-radioactive **Potassium**-39.

During the explosion, **Argon** gas trapped within the lava is expelled. Over time the radioactive **Potassium**-40 breaks down into **Argon**-40 which is trapped in the structure of the hardened lava. The isotope **potassium**-40 decays into **argon**-40 at a predictable rate.

One such example is **potassium**-**argon** **dating**, where **potassium** decays into **argon**.

**Potassium** reacts violently with just water while **argon** is very inert and stable, which is why it remains in the atmosphere as a monatomic element.

*Argon* and *potassium* are reversed on the periodic table.

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Join Britannica's Publishing Partner Program and our community of experts to gain a global audience for your work! This *dating* method is based upon the decay of radioactive *potassium*-40 to radioactive *argon*-40 in minerals and rocks; *potassium*-40 also decays to calcium-40.