Radioactive dating can be defined in terms of physics and measurement. Radioactive sample amount follows an exponential decay curve. Every substance used for radioactive dating has a characteristic half-life. Though useful, radioactive dating has limits due to instrumental limitations.

Nucleic Emissions

Radiation emissions that change nucleon (proton and neutron) count in an atom. Emissions consist of alpha particles (helium nuclei), beta rays (electrons or positrons), and gamma rays.

Exponential Decay

Decay of a radioactive substance is described by the exponential decay equation. Exponential decay relates radioactive material amount with respect to time assuming a constant decay rate characteristic of that material.

Half-Life

Particle emission frequency is standardized by the half-life concept. Half-life is the time it takes for half of a radioactive sample to decay into a different isotope or element. Some substances, like uranium isotopes, have half-lives spanning millions of years.

Substances of Interest

Carbon, potassium and uranium isotopes are commonly used in radiometric dating. Isotope(s) measured depend on time frame of interest and measurement reliability.

Measurement Limitations

As original isotope amount decreases, measurement reliability becomes an issue. This is explained by the nearly-flat quality of exponential decay curves when uncertainty in measured amount (y-axis) is very small, thereby corresponding to a large elapsed time uncertainty (x-axis).

Source:

Georgia State University. "Radioactive Dating"

California State University, Northridge. "Absolute Time"

Science Education Resource Center, Carleton College. "How Does Radioactive Decay Work?"

Resource:

Information on Potassium-Argon Dating

Information of Radioactive Dating

Information on Uranium Decay