How Does Radiometric Dating Work?
Radioactive Dating and Science
Radiometric dating, or as it is more commonly known, radioactive dating, is a scientific procedure used to determine the absolute age of an object and has been used to help establish the geological timescale. Radioactive dating is a scientifically tested and valid technique, although some non-scientists enjoy doubting results obtained with dating techniques. These techniques make use of the tendency for certain isotopes of an element to decay over time in a predictable way; looking at the decay retrospectively, it is possible to calculate when the original isotopes were incorporated into the material.
Isotopes, Half-life and Decay
Any atom of an element is guaranteed to have the same number of protons as any other atom of that element, but not necessarily the same number of neutrons. Neutrons, the neutral subatomic particle, occasionally are ejected from the atom by a number of processes such as beta decay or emission of positrons or alpha particles. These variations are called isotopes and denoted with a number after the element name, such as carbon-12 or carbon-13. While it is impossible to predict when an individual atom will shed a neutron by decaying, the decay of a group of atoms in an element is very predictable. Scientists use the term "half-life" to refer to the time period it takes for half of the atoms in the material to decay down to the next lowest isotope. These half-lives vary from material to material and from element to element but are known values.
Using Known Half-life to Calculate Unknown Age
When scientists use radiometric dating, they use a mass spectrometer to analyze the isotopes present in the material, both of the old material and of the new, decayed isotope. Using the known half-life of materials (for example, the half-life of carbon-14 is 6,000 years), scientists can compare how much of each type of isotope (the original isotope, known as the parent, and the decayed isotope, known as the daughter isotope) is present in the material. Using this information, highly accurate dating can be established for even very old objects.
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