What is the Definition of “Atomic Isotope?
Atoms of Cobalt-60, strontium-90, Bismuth-213, Iodine-125–these are all radioactive isotopes used in medical treatment procedures. Many elements exist as more than one isotope. A high percentage of them are not radioactive. Just what exactly is an isotope? It involves the central portion of the atom–the nucleus. The Atom as a Whole The nucleus of the atom is a combination of protons and neutrons, held together by a kind of glue termed “strong force.” The protons are very small, positively charge particles, whereas the neutrons have no charge. Surrounding the nucleus and traveling in specific trajectories called orbitals are negatively charged electrons. In a neutral atom, the number of electrons equals the number of protons that are in the nucleus. In discussing isotopes, the electrons are not a determining factor. The Nucleus The number of protons determines the variety of an element. A nucleus with one proton is hydrogen. A nucleus with five protons is boron. A nucleus with ninety-
