부산대학교 도서관

Isotopes are atoms of the same chemical element with the same number of protons in their nucleus (and hence the same chemical properties) but different numbers of neutrons, resulting in different atomic masses. Most natural chemical elements have at least two isotopes, which are conventionally denoted by their atomic mass (e.g. the isotopes of copper, 63Cu and 65Cu). Although many isotopes are stable, numerous elements also have one or more radioactive unstable isotopes, produced either as a result of specific nuclear processes (such as the production of 14C by the interaction of cosmic rays with 14N in the upper atmosphere), or via the radioactive decay of heavier unstable elements. Carbon, for example, has two stable isotopes (12C and 13C) and the radioisotope 14C. Lead has four stable isotopes (204Pb, 206Pb, 207Pb, 208Pb) and over thirty radioactive isotopes. Tin has the largest number of stable isotopes—ten....