18-1 Why are some atomic nuclei stable?
� The strong nuclear force overcomes the repulsive force between protons to keep the nucleus intact.____
� The energy released when the nucleons form a nucleus is known as the mass defect.____
� The mass that is converted to energy when nucleons form a nucleus is known as the mass defect.____
� If the mass defect is known, the nuclear binding energy can be calculated by using the equation E= mc2.____
� The ratio of neutrons to protons in stable nuclei defines a band of stability that includes the stable nuclei.____
18-2 What kinds of nuclear change occur?
� Unstable nuclei are radioactive and can emit radiation in the form of alpha particles, beta particles, and gamma rays.____
� Unstable nuclei with too many neutrons usually emit beta particles.____
� Unstable nuclei with too few neutrons can undergo either electron capture, or position emission, emitting gamma rays in the process.____
� Large nuclei with too few neutrons frequently emit alpha particles.____
� Nuclear equations are balanced in terms of mass and charge.____
� In nuclear fission, a heavy nucleus splits into two smaller nuclei; in nuclear fusion, two smaller nuclei combine to form one larger nucleus.____
� Nuclear fission reactions that cause other fissions are chain reactions. Sustained chain reactions must be controlled to avoid a nuclear explosion.____
� Nuclear reactions result in a transmutation.____
18-3 How is nuclear chemistry used?
� Half-life is the time required for one half of the mass of a radioactive isotope to decay.____
� The half-life of the carbon-14 isotope can be used to date organic material that is up to 20,000yrs old. Other radioactive isotopes are used to date older rock and mineral formations.____
� Radioactive isotopes have a number of practical applications in industry, medicine, and chemical analysis.____
� The biological effects of radiation are measured in units called rems.____