Isotopes are forms of an element that have a different number of neutrons than that element normally has. Because the number of neutrons varies in isotopes, the isotope has some properties that make it unique. Isotopes can be stable or unstable. An unstable isotope will be radioactive and therefore emit radiation energy. That energy can be used in medicine, industry and for scientific lab purposes.
-carbon 12, carbon 13, carbon 14
-oxygen 16, oxygen 18
-phosphorous 31, phosphorous 32