Radioactive dating, also known as radiometric dating or radioisotope dating, is a technique used to date materials such as rocks, fossils, and artifacts by measuring the amounts of radioactive isotopes and their decay products in the material.
The use of radiometric dating was first published in 1907 by Bertram Boltwood and is now the principal source of information about the absolute age of rocks and other geological features, including the age of the Earth itself, and can be used to date a wide range of natural and man-made materials.
How Radioactive Decay Works All atoms have a nucleus, which is made up of protons and neutrons. Some atoms have unstable nuclei, which means that they can spontaneously decay into different atoms. This process is called radioactive decay. During radioactive decay, the unstable atom (known as the parent isotope) emits radiation and is converted into a more stable atom (known as the daughter isotope). The rate of radioactive decay is constant for a particular isotope, and is not affected by environmental factors such as temperature or pressure. This means that the ratio of parent to daughter isotopes in a sample can be used to calculate the age of the sample.
Half-Life The half-life of a radioactive isotope is the amount of time it takes for half of the atoms in a sample to decay. Half-lives can range from seconds to billions of years.
How Radioactive Dating Is Used
To date a material using radioactive dating, scientists first need to choose an appropriate radioactive isotope. The isotope must be present in the sample, and it must have a half-life that is appropriate for the age of the sample. The half-life of an isotope is the time it takes for half of the parent atoms in a sample to decay into daughter atoms.
Once a radioactive isotope has been chosen, scientists measure the ratio of parent to daughter isotopes in the sample. This can be done using a variety of techniques, such as mass spectrometry or scintillation counting. Once the ratio has been measured, scientists can use a mathematical equation to calculate the age of the sample.
For example, carbon-14 has a half-life of 5,730 years. This means that half of the carbon-14 atoms in a sample will decay into nitrogen-14 atoms every 5,730 years. If a sample of wood contains half as much carbon-14 as it would if it were freshly alive, then the sample is approximately 5,730 years old.
Types of Radioactive Dating Methods There are many different types of radioactive dating methods, each of which uses a different radioactive isotope and decay product. Some common radioactive dating methods include:
Radioactive dating is a powerful tool that has been used to make many important discoveries in science and history. It is a complex technique, but the basic principles are relatively simple.