CK-12-Physics-Concepts - Intermediate

22.3 Nuclear Reactions

22.3 Nuclear Reactions

• Write correct equations for nuclear reactions.


• Define half-life.


• Calculate amount of material remaining after a given number of half-lives.

Operation Castle was a series of nuclear tests that the USA conducted in 1954 in the Bikini and Enewetok atolls in
the Marshall Islands of the Pacific. The purpose of the tests was to validate the designs of different thermonuclear
weapons.

Nuclear Reactions

In all nuclear reactions, the total of the atomic numbers on the left side of the equation must equal the total of the
atomic numbers on the right side of the equation. Furthermore, the sum of the mass numbers on the left of the
equation must equal the sum of the mass numbers on the right of the equation. In addition to alpha and beta decay,
there are a number of other types of nuclear reactions. Bombardment of nuclei with alpha particles or neutrons can
often produce a nuclear reaction. Consider the bombardment of nitrogen-14 by an alpha particle,

4

2 He+

14

7 N→

1

1 H+

17

8 O

or the bombardment of uranium-235 by a neutron.

235

92 U+

1

0 n→

89

36 Kr+

144

56 Ba+^3

1

0 n

Large unstable nuclei often become more stable by breaking into smaller pieces. The breakup of a larger nucleus
into two or more smaller nuclei is calledfission. Small nuclei often become more stable by joining together to form
larger nuclei. This process is calledfusion.