Chemistry (Chang), 9th Edition

Chapter 23: Nuclear Chemistry

Chapter Summary

1. For stable nuclei of low atomic number, the neutron-to-proton ratio is close to 1. For heavier stable nuclei, the ratio becomes greater than 1. All nuclei with 84 or more protons are unstable and radioactive. Nuclei with even atomic numbers tend to have a greater number of stable isotopes than those with odd atomic numbers.

2. Nuclear binding energy is a quantitative measure of nuclear stability. Nuclear binding energy can be calculated from a knowledge of the mass defect of the nucleus.

3. Radioactive nuclei emit α particles, β particles, positrons, or g rays. The equation for a nuclear reaction includes the particles emitted, and both the mass numbers and the atomic numbers must balance.

4. Uranium-238 is the parent of a natural radioactive decay series that can be used to determine the ages of rocks.

5. Artificial radioactive elements are created by bombarding other elements with accelerated neutrons, protons, or α particles.

6. Nuclear fission is the splitting of a large nucleus into two smaller nuclei and one or more neutrons. When the free neutrons are captured efficiently by other nuclei, a chain reaction can occur.

7. Nuclear reactors use the heat from a controlled nuclear fission reaction to produce power. The three important types of reactors are light water reactors, heavy water reactors, and breeder reactors.

8. Nuclear fusion, the type of reaction that occurs in the sun, is the combination of two light nuclei to form one heavy nucleus. Fusion takes place only at very high temperatures, so high that controlled large-scale nuclear fusion has so far not been achieved.

9. Radioactive isotopes are easy to detect and thus make excellent tracers in chemical reactions and in medical practice.

10. High-energy radiation damages living systems by causing ionization and the formation of free radicals.