Recall that atoms are the basic building blocks of matter.

Atoms are made up of much smaller particles called protons, neutrons, and electrons.

During the lifetime of an organism, the amount of c14 in the tissues remains at an equilibrium since the loss (through radioactive decay) is balanced by the gain (through uptake via photosynthesis or consumption of organically fixed carbon).

However, cosmic radiation constantly collides with atoms in the upper atmosphere.

Scientists use a technique called radiometric dating to estimate the ages of rocks, fossils, and the earth.

Many people have been led to believe that radiometric dating methods have proved the earth to be billions of years old.

This discovery meant that there are three naturally occurring isotopes of carbon: Whereas carbon-12 and carbon-13 are stable isotopes, carbon-14 is unstable or radioactive.

Carbon-14 is produced in the upper atmosphere when cosmic rays bombard nitrogen atoms.