# Radiometric Methods of Dating Fossils

## 7 Pages

Excerpt

Abstract

Introduction:

Carbon-14 Dating:

Uranium-238:

Conclusion:

References

## Abstract

Today, most of the methods utilized for chronometric dating of fossils are radiometric. Radiometric dating, in general, refers to the dating of material by using the known rate at which certain radioactive isotopes decay, or at what rate there are collective changes due to radioactivity. Even though isotopes of an element can be different when it comes to atomic mass, the atomic number of the isotope is always the same.

Radioactive elements decay at unique rates, dependant on the isotope. This rate of decay is known as half-lives, it is the time necessary for ½ of the atoms to decay in a particular element. The decay follows a geometric scale, in that in the first half-life of an element, ½ of the atoms decay, yet in the second half-life, ½ of those remaining decay, meaning a ¼ of the original atoms decay, and so forth. By measuring this decay, and knowing the half life of an element, scientists can date a sample.

## Introduction:

Today, most of the methods utilized for chronometric dating of fossils are radiometric. Radiometric dating, in general, refers to the dating of material by using the known rate at which certain radioactive isotopes decay, or at what rate there are collective changes due to radioactivity. Even though isotopes of an element can be different when it comes to atomic mass, the atomic number of the isotope is always the same.

Radioactive elements decay at unique rates, dependant on the isotope. This rate of decay is known as half-lives, it is the time necessary for ½ of the atoms to decay in a particular element. The decay follows a geometric scale, in that in the first half-life of an element, ½ of the atoms decay, yet in the second half-life, ½ of those remaining decay, meaning a ¼ of the original atoms decay, and so forth. By measuring this decay, and knowing the half life of an element, scientists can date a sample.

## Carbon-14 Dating:

One of the most common forms of radiometric dating applied today is radiocarbon, or Carbon-14 dating. This method is used in the dating of organic materials. Cosmic radiation is constantly assailing the Earth’s atmosphere, and when it hits an atom of nitrogen, it alters the nucleus, changing the atom into hydrogen and Carbon-14. These two atoms then bond with oxygen and form carbon dioxide, which is utilized by plants in photosynthesis. Animals then eat these plants, then other animals eat these animals, and the spread of Carbon-14 through all living things is completed.

When an organism is alive, it consumes Carbon-14 at the same ratio as what is in the Earth’s atmosphere. However, once an organism dies, they no longer consume Carbon-14, and the Carbon-14 that was in their body begins to decay into the more stable Carbon-12. It is this rate of decay that is measured and used to date the organism.

In the conventional testing of Carbon-14, the process involved the scientist burning a sample of the material being tested in a closed vessel, with nothing else but pure oxygen. Most of the carbon from the sample combines with the oxygen, during the combustion process, and forms carbon dioxide, which is cooled to a liquid state, and then placed into a lead shielded box. A Geiger counter is then used to measure the radioactivity of the Carbon-14 atoms. The release of beta particles from the Carbon-14 decay is measured over a specified period of time. As older samples have less Carbon-14, less beta particles will be measured.

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Details

Title
College
University of Phoenix
Author
Year
2004
Pages
7
Catalog Number
V57779
ISBN (eBook)
9783638521161
ISBN (Book)
9783656791102
File size
430 KB
Language
English
Tags
Quote paper
Kimberly Wylie (Author), 2004, Radiometric Methods of Dating Fossils, Munich, GRIN Verlag, https://www.grin.com/document/57779

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