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Energy and mass are related by Einstein’s famous equation of scintillation counter (p. 331)
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E = mc , which means that matter can be converted to energy and secondary loop (p. 341)
energy to matter. The mass of a nucleus is always less than the sum shell model of the nucleus (p. 327)
of the masses of the individual particles of which it is made. This steam generator (p. 341)
mass defect of a nucleus is equivalent to the energy released when the
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nucleus was formed according to E = mc . It is also the binding energy,
the energy required to break the nucleus apart into nucleons. APPLYING THE CONCEPTS
When the binding energy is plotted against the mass number,
the greatest binding energy per nucleon is seen to occur for an atomic
1. Natural radioactivity is a result of
number near that of iron. More massive nuclei therefore release energy a. adjustments to balance nuclear attractions and repulsions.
by fission, or splitting to more stable nuclei. Less massive nuclei release b. experiments with human-made elements.
energy by fusion, the joining of less massive nuclei to produce a more c. absorption of any type of radiation by very heavy elements.
stable, more massive nucleus. Nuclear fission provides the energy for d. a mass defect of the nucleus.
atomic explosions and nuclear power plants. Nuclear fusion is the 2. Which one of the following is an electron emitted by a nucleus as
energy source of the Sun and other stars and also holds promise as a it undergoes radioactive decay?
future energy source for humans. The source of the energy of a nucleus a. Alpha particle
can be traced back to the gravitational attraction that formed a star. b. Beta particle
c. Gamma ray
d. Z ray
SUMMARY OF EQUATIONS 3. Which one of the following is an alpha particle emitted by a
nucleus as it undergoes radioactive decay?
13.1
a. Electron
energy = mass × the speed of light squared
b. Helium nucleus
E = mc 2 c. Photon of very short wavelength
d. Z ray
4. Protons and neutrons collectively are called
KEY TERMS a. particles.
b. nucleons.
alpha particle (p. 325) c. heavy particles.
background radiation (p. 334) d. alpha particles.
band of stability (p. 327) 5. The number of protons and neutrons in a nucleus defines the
beta particle (p. 325) a. atomic number.
binding energy (p. 335) b. neutron number.
chain reaction (p. 337) c. nucleon number.
d. mass number.
control rods (p. 339)
critical mass (p. 337) 6. Atoms with the same atomic number but with different numbers
of neutrons are
curie (p. 332)
a. allotropes.
electromagnetic force (p. 327)
b. isomers.
fuel rod (p. 339)
c. isotopes.
gamma ray (p. 325)
d. allomers.
Geiger counter (p. 331)
7. Which of the following types of radiation will not penetrate
half-life (p. 330)
clothing?
ionization counter (p. 331) a. Alpha particles
mass defect (p. 335) b. Beta particles
moderator (p. 340) c. Gamma rays
nuclear fission (p. 336) d. X rays
nuclear force (p. 327) 8. The half-life of a radioactive isotope is the time required for
nuclear fusion (p. 336) one-half of
nuclear reactor (p. 339) a. any size sample to sublimate.
nucleons (p. 325) b. a molar mass to disappear through radioactivity.
plasma (p. 345) c. the total radioactivity to be given off.
d. the nuclei of any size sample to decay.
primary loop (p. 340)
rad (p. 333) 9. The activity of a radioactive source is measured in units of
a. curie.
radioactive decay (p. 325)
b. rad.
radioactive decay series (p. 329)
c. rem.
radioactivity (p. 324)
d. roentgen.
rem (p. 333)

13-25 CHAPTER 13 Nuclear Reactions 347