Chapter 25, Problem 50A

Interpretation Introduction

Interpretation:

Nuclear fission and a nuclear chain reaction are to be described.

Concept introduction:

The process of radioactive decay is how an unstable atomic nucleus loses energy through radiation. A substance that has unstable nuclei is regarded as radioactive.

Answer to Problem 50A

The nuclei of isotopes (that are fissionable) are bombarded with neutrons, which causes them to split into smaller fragments and consequently release more neutrons. These also hit other fissionable nuclei to start a chain reaction that releases large amounts of energy.

Explanation of Solution

Nuclear chain reactions are the processes in which neutrons released in fission produce additional fission in at least one further nucleus. This nucleus produces neutrons, and again the process repeats. This process may be controlled (nuclear power) or uncontrolled (nuclear weapons).

In a fission chain reaction, a fissionable nucleus absorbs a neutron and fissions spontaneously which releases additional neutrons. These can be absorbed by other fissionable nuclei, releasing still more neutrons.

Conclusion

Nuclear chain reactions are a succession of nuclear fissions, or the breaking of atomic nuclei, with each fission being started by a neutron created in the one before it.