what is an isotope

Isotopes are atoms of the same element that have the same number of protons (atomic number) but a different number of neutrons, meaning that their mass number varies. They have the same position in the periodic table as the element they belong to, but differ in nucleon numbers due to different numbers of neutrons in their nuclei. For example, hydrogen has three naturally occurring isotopes: protium (hydrogen-1), deuterium (hydrogen-2), and tritium (hydrogen-3) . Isotopes of the same element have nearly identical chemical and physical properties, but their nuclear properties vary, making some invaluable for mankind, while others have no practical value. Isotope analysis is the determination of isotopic signature, the relative abundances of isotopes of a given element in a particular sample, and is frequently done by isotope ratio mass spectrometry.