•The average annual radiation dose is only about 0.27 rem. About 80% of this background radiation comes from natural sources the remaining 20% comes from medical procedures and from consumer products.
Stable and Unstable Isotopes►An atom is stableif the forces among the particles that make up the nucleus are balanced. ►An atom is unstable (radioactive)if these forces are unbalanced--if the nucleus has an excess of internal energy. ►Unstable atoms are called radioisotopes.►The instability of a radioisotope's nucleus may result from an excess of either neutrons or protons.
Table 15.02Fig. 15.14
Nuclides and Radionuclides•Nuclide= the nucleus of a specific isotope. •Each nuclide has a unique set of characteristics(1) number of protons, (2) number of neutrons, (3) energy state.If any of these characteristics change, the atom becomes a different nuclide (~3,700 nuclides have been identified). •Most of them are radionuclides, meaning they are unstable nucleus of a radioisotope and undergo nuclear decay.•All isotopes of elements with atomic numbers higher than that of bismuth (83) are radioactive.
15-1215.2 Nuclear ReactionsTwo conditions must be met to balance a nuclear equation:1.Conservation of mass number2.Conservation of nuclear charge (atomic number)Examples:•Nuclear decay: The spontaneous emission of a particle from an unstable nucleus.Radioactive nucleus new nucleus + radiation•Transmutation: The change of one element into another.