# Explain how radioactive dating works

From then on, the ratio of radiocarbon to stable carbon will decrease, because the unstable radiocarbon atoms will slowly decay. From this measurement the age in radiocarbon years is calculated. Modern radiocarbon dates are calibrated using long tree-ring chronologies.

Radiocarbon is not stable; over time radiocarbon atoms decay into nitrogen atoms.

The probability of a parent atom decaying in a fixed period of time is always the same for all atoms of that type regardless of temperature, pressure, or chemical conditions. The time required for one-half of any original number of parent atoms to decay is the half-life, which is related to the decay constant by a simple mathematical formula.

All rocks and minerals contain long-lived radioactive elements that were incorporated into Earth when the Solar System formed.

The above equation makes use of information on the composition of parent and daughter isotopes at the time the material being tested cooled below its closure temperature.

This is well-established for most isotopic systems.