a nonmetallic element existing in the three crystalline forms: graphite, diamond, and buckminsterfullerene: occurring in carbon dioxide, coal, oil, and all organic compounds.The isotope carbon-12 has been adopted as the standard for atomic wt.; carbon-14, a radioisotope with a half-life of 5700 years, is used in radiocarbon dating and as a tracer.This method includes carbon dating and thermoluminescence.
Carbon dioxide from the atmosphere is synthesized by plants into plant tissue, which is ingested and metabolized by animals and reduced to carbon dioxide again during respiration and decaya colourless odourless incombustible gas present in the atmosphere and formed during respiration, the decomposition and combustion of organic compounds, and in the reaction of acids with carbonates: used in carbonated drinks, fire extinguishers, and as dry ice for refrigeration.
The first method was based on radioactive elements whose property of decay occurs at a constant rate, known as the half-life of the isotope.
Today, many different radioactive elements have been used, but the most famous absolute dating method is radiocarbon dating, which uses the isotope C.
Relative techniques can determine the sequence of events but not the precise date of an event, making these methods unreliable.
b) Absolute These methods are based on calculating the date of artefacts in a more precise way using different attributes of materials.