Why are neutrons, not protons, used in nuclear fission reactions?

Neutrons are used in nuclear fission reactions because they can easily penetrate and split the nucleus of an atom.

In nuclear fission reactions, the nucleus of an atom is split into two or more smaller nuclei, along with the release of a large amount of energy. This process is initiated by the absorption of a neutron by the nucleus. Neutrons are uncharged particles, which means they are not repelled by the positive charge of the protons in the nucleus. This allows them to penetrate the nucleus easily and cause it to become unstable, leading to fission.

Protons, on the other hand, carry a positive charge. When a proton approaches a nucleus, it is repelled by the positive charge of the protons in the nucleus due to the electrostatic force. This makes it difficult for protons to penetrate the nucleus and initiate a fission reaction. Even if a proton does manage to penetrate the nucleus, the resulting nucleus would be positively charged and would immediately eject the extra proton, making the fission process inefficient.

Furthermore, neutrons are more effective in sustaining a chain reaction, which is crucial in nuclear fission reactions. When a nucleus undergoes fission, it releases additional neutrons, which can then be absorbed by other nearby nuclei, causing them to also undergo fission. This chain reaction leads to the release of a large amount of energy, which is the principle behind nuclear power and atomic bombs.

In summary, the use of neutrons in nuclear fission reactions is due to their ability to easily penetrate the nucleus, their effectiveness in initiating and sustaining a chain reaction, and the inefficiency and impracticality of using protons.