In Carbon-14, the radioactive isotope of Carbon used in Carbon Dating, has 6 Protons, 8 Neutrons and 6 Electrons. Carbon 14 has a half life of 5,730 years and by checking the amount of the carbon 14 is in a fossil the can see how old it is. Carbon 14 is also a natural isotope but radioactive; it is important for radiocarbon dating of materials from organic origin.Yes: it cannot date things older than ~40,000 years as the carbon-14 isotope has decayed to practically undetectable levels after that much time as levels of the carbon-14 isotope in the atmosphere vary slightly over time (it is produced by the flux of cosmic rays hitting earth, which varies as the solar system orbits the galaxy, etc.) the dating method must be recalibrated using tree ring count reference samples to keep it accurate over long…
Since every living creature had organic matter and carbon is an integral part of that organic matter, it is conventional to use carbon isotope.
Carbon dating has the peculiar property that it works primarily on dead things.
Other forms of radioactive dating are more broadly applicable. It decays to Nitrogen 14 and has a half life of 5,730 years.
Uranium comes in two common isotopes with atomic weights of 235 and 238 (we'll call them 235U and 238U).
Both are unstable and radioactive, shedding nuclear particles in a cascade that doesn't stop until they become lead (Pb).For carbon dating, the isotope used is Carbon-14, which has a half life of 5,700 years. If so, the official definition is "the determination of the age or date of organic matter from the relative proportions of the carbon isotopes carbon-12 and carbon-14 that it contains".