Because the decay products in the above fission reaction are neutron rich, they will likely decay by what process?
A. Alpha decay
B. Beta decay
C. Gamma decay

The uranium isotope \({ }^{235} \mathrm{U}\) can fission-break into two smaller-mass components and free neutrons-if it is struck by a free neutron. A typical reaction is

\[{ }_{0}^{1} \mathrm{n}+{ }_{92}^{235} \mathrm{U} \rightarrow{ }_{56}^{141} \mathrm{Ba}+{ }_{36}^{92} \mathrm{Kr}+3{ }_{0}^{1} \mathrm{n}\]

As you can see, the subscripts (the number of protons) and the superscripts (the number of nucleons) "balance" before and after the fission event; there is no change in the number of protons or neutrons. Significant energy is released in this reaction. If a fission event happens in a large chunk of \({ }^{235} \mathrm{U}\), the neutrons released may induce the fission of other \({ }^{235} \mathrm{U}\) atoms, resulting in a chain reaction. This is how a nuclear reactor works.

The number of neutrons required to create a stable nucleus increases with atomic number. When the heavy \({ }^{235} \mathrm{U}\) nucleus fissions, the lighter reaction products are thus neutron rich and are likely unstable. Many of the short-lived radioactive nuclei used in medicine are produced in fission reactions in nuclear reactors.