chem 15

Nuclear reactions, unlike ordinary chemical reactions, usually change one element into one or more other ___________. This process is called ___________. The energy produced in nuclear reactions is much ___________than that involved in any chemical reaction. Unlike ordinary chemical reactions, in nuclear reactions the total quantity of matter is typically changed and different isotopes of an element exhibit ___________behaviors. Radioactive isotopes have ___________chemical properties as the nonradioactive isotopes of the same element.

The spontaneous change of an unstable nuclide into another is ___________decay. Atoms undergo radioactive decay to become more ___________. The unstable nuclide is called the ___________nuclide; the nuclide that results from the decay is known as the daughter nuclide. The daughter nuclide may be stable, or it may ___________itself. There is no known way to control natural radioactive decay. It cannot be sped up, slowed down, or ___________.

A nuclear equation must be balanced in both mass and nuclear ___________. Different types of particles can be emitted or captured during radioactive decay. 

Alpha decay is the emission of an alpha particle from the nucleus. Alpha decay occurs primarily in heavy nuclei (A > 200, Z > 83) and leaves a daughter nuclide with a larger n:p ratio than the parent nuclide.

Beta decay is the emission of an ___________from a nucleus. Emission of an electron does not change the mass number of the nuclide but does ___________the number of its protons and decrease the number of its neutrons. Beta decay is observed in nuclides with a large n:p ratio which decreases.

Gamma emission is observed when a nuclide is formed in an excited state and then decays to its ___________state with the emission of a γ ray. There is no change in mass number or ___________number.

Positron emission is the emission of a positron from the nucleus in which the n:p ratio is low. The n:p ratio increases with positron emission.

Electron capture occurs when an inner shell ___________combines with a proton and is converted into a neutron. The loss of an inner shell electron leaves a vacancy that will be filled by one of the outer electrons with the release of ___________. Electron capture has the same effect on the nucleus as does positron emission: the atomic number is ___________by one and the mass number does not change. This increases the n:p ratio.

Artificial radioactivity is induced by the bombardment of certain nuclei with subatomic particles. ___________is the breaking of a large nuclide into two smaller nuclides. Not all isotopes are capable of undergoing nuclear fission. One of the projectiles most often used in modern times to initiate nuclear reactions is the ___________. A neutron does not need as high an energy as an alpha particle or a proton because it is uncharged and can penetrate a nucleus more easily than a positively charged particle can. Fission is triggered by striking the parent nuclide with a low-energy neutron and creates a mixture of different product isotopes.

Nuclear ___________reactions combine two small nuclei to form one larger one. Nuclear fusion reactions generate tremendous quantities of energy. The reactant and product isotopes are not necessarily radioactive.

Practice Problems

70. Classify these nuclear reactions as decay, fission, or fusion.

a. 1H + 2H → 3He + 0γ

b. 220Rn → α + 216Po

c. n + 235U → 90Sr + 143Xe + 3 n

5. Complete each of the following radioactive decay equations:

a. 210Bi → β− + ?

b. 106Ag → 106Cd + ?

c. 68Ge + e → ?

51. Complete each of the following equations and classify them as fission or fusion.

a. 3He + 2H → 4He + ?

b. 239Pu + n → 95Zr + ? + 2 n

c. 244Am → 134I + ? + 3 n

d. 43Ca + 4He → p + ?

Kinetics