If you have looked at a periodic table, you may have noticed that the atomic mass of an element is rarely an even number. If you are an atom with an extra electron, it's no big deal.
As you learn more about chemistry, you will probably hear about carbon-14. C-14 is considered an isotope of the element carbon.
One way that helps scientists place fossils into the correct era on the Geologic Time Scale is by using radiometric dating.
Half-life is defined as the time it takes for one-half of a radioactive element to decay into a daughter isotope.
Perhaps the most widely used evidence for the Theory of Evolution through Natural Selection is the fossil record.
The fossil record may be incomplete and may never fully completed, but there are still many clues to evolution and how it happens within the fossil record.
The atoms of some chemical elements have different forms, called isotopes.
These break down over time in a process scientists call radioactive decay.