Carbon-14 is the isotope of the carbon element. It has 8 neutrons in its nucleus; together with the 6 protons which is characteristic of carbon atoms, it’s number is 14 in periodic table. Carbon-14 is radioactive and decays into nitrogen-14, which is not radioactive. This is done via beta decay. The half-life of carbon-14 is 5730 ± 40 years.
The carbon-14 dating method is used for determining the age of organic materials based on their carbon-14 content.
The carbon-14 isotope is formed naturally from nitrogen atoms in the atmosphere’s upper layer (the stratosphere and the top of the troposphere). Two other isotopes of carbon are and , and these are respectively 99% and 1% of the earth carbon atoms. Carbon-14, on the other hand, represents only a very small amount; one in one billion, . All organic molecules contain carbon atoms, all organic matter also consists of a small amount of these carbon-14 atoms. Even though it is very small, it is still possible to measure the carbon-14 atoms content in an organic material.
In living organisms, such as animals, plants and humans, there is a constant amount of the carbon atoms. This is due to human consumption of food (which naturally contains carbon atoms) and the exhalation of carbon atoms in the form of carbon dioxide . Therefore, the carbon-14 atoms also represent 1 in 1 billion of all the carbon atoms of all living organisms. Carbon-14 is radioactive and the amount of carbon-14 atoms is halved at about 5730 years. Therefore, by measuring the content of carbon-14 in a dead organism and then comparing it with the contents of living organisms, we can determine how long has elapsed since the organism died.
Half-life of carbon-14
Since the half-life of carbon-14 is 5730, you can of course not use the carbon-14 method for dating that has died recently. This is because, for example, measurements on samples that are 5 years old will be subject to very high uncertainty because only a very small part of the carbon-14 atoms will be decayed. However, because the carbon-14 content is so limited, the method is not used for dating older than 50,000 years.
In practice, using a mass spectrometer, you simply measure the number of carbon-14 atoms in, for example, a small sample of the bones. Based on this content, an annual figure is calculated using the formulas that apply in radioactivity and decay.
The geological application of the carbon-14 method has made it possible to set a time scale for developments in the climate and vegetationof the Earth. Previously, you only knew which plants and what climatic conditions were in earth, but now you can put a chronological overview.
The carbon-14 method is a suitable and useful method, as it is globally available and does not depend on regional differences. This is due to the fact that the concentration of carbon-14 atoms is almost constant throughout the globe. In addition, the inventors of this method were honored with the Nobel Prize in Chemistry in 1960, as the method was revolutionary in today’s dating techniques.