# Why is it important in carbon dating to consider the ratio of carbon-14 atoms to other carbon atoms, rather than only the number of carbon-14 atoms?

In living organisms, the C-14 to C-12 ratio is constant. However, in non-living organisms C-14 < C-12. Upon death C-14 begins to decay. Since all radio decay is 1st order kinetics, then the time for C-14 to decay to present day measurement is easily calculated from the 1st order decay equation ${C}_{\text{final" = C_"initial"e^"-kt}}$. The rate constant (k) = $\frac{0.693}{t} _ \left(\frac{1}{2}\right)$ where ${t}_{\frac{1}{2}}$ for C-14 $\approx 5700 y r s .$