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How is radioactive carbon-14 used in radiocarbon dating?
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carbon group element
Modern version of the periodic table of the elements (printable).
Radiocarbon dating is a method used to determine the age of organic materials by measuring the decay of the radioactive isotope carbon-14.12
The Process
- Formation: Carbon-14 is continuously created in the upper atmosphere when cosmic rays collide with nitrogen atoms, producing neutrons that transform nitrogen-14 into carbon-14.13
- Absorption: This carbon-14 bonds with oxygen to form carbon dioxide, which enters the carbon cycle through photosynthesis in plants and subsequent consumption by animals.13
- Death and Decay: While an organism is alive, its carbon-14 levels remain relatively stable. Upon death, it stops taking in carbon, and the carbon-14 in its tissues begins to decrease at a constant rate through beta decay, reverting to nitrogen-14.13
- Measurement: With a half-life of 5,730 ± 40 years, researchers use an accelerator mass spectrometer to measure the remaining carbon-14 and calculate the time elapsed since the organism died.143
Because atmospheric carbon levels have fluctuated over time, raw dates are often calibrated using dendrochronology or other known-age samples to improve accuracy.43