In this equation, the units of measure for N and No can be in grams, atoms, or moles.It does not matter as long as they are like measures.The units of measure for time are dependent upon the unit of measure for the rate constant.

As long as the organism is alive, the amount of carbon-14 remains relatively constant.

However, when the organism dies, the amount will decrease over time.

By comparing the activity of an archeological artifact to that of a sample of the living organism one can estimate the age of the artifact.

The amount of carbon-14 in the atomosphere is, on an average, relatively constant.

Plants take in carbon-14 through the process of photosynthesis.

Animals eat the plants so they too have carbon-14 in their tissues.

Carbon-14 is decaying constantly with a half-life of 5720 years.

It has been determined that the rate of radioactive decay is first order.

We can apply our knowledge of first order kinetics to radioactive decay to determine rate constants, original and remaining amounts of radioisotopes, half-lives of the radioisotopes, and apply this knowledge to the dating of archeological artifacts through a process known as carbon-14 dating.

, where r is a measurement of the rate of decay, k is the first order rate constant for the isotope, and N is the amount of radioisotope at the moment when the rate is measured.

The rate of decay is often referred to as the activity of the isotope and is often measured in Curies (Ci), one curie = 3.700 x 10" is the initial amount of radioisotope at the beginning of the period, and "k" is the rate constant for the radioisotope being studied.