Recall that atoms are the basic building blocks of matter.
Atoms are made up of much smaller particles called protons, neutrons, and electrons.
Protons and neutrons make up the center (nucleus) of the atom, and electrons form shells around the nucleus.
The number of protons in the nucleus of an atom determines the element.
Scientists use a technique called radiometric dating to estimate the ages of rocks, fossils, and the earth.
So, a carbon atom might have six neutrons, or seven, or possibly eight—but it would always have six protons.An “isotope” is any of several different forms of an element, each having different numbers of neutrons.For example, all carbon atoms have 6 protons, all atoms of nitrogen have 7 protons, and all oxygen atoms have 8 protons.The number of neutrons in the nucleus can vary in any given type of atom.
Note that, contrary to a popular misconception, carbon dating is not used to date rocks at millions of years old.Before we get into the details of how radiometric dating methods are used, we need to review some preliminary concepts from chemistry.