IV.

Nuclear Reactions

Nuclear chemistry also involves the study of nuclear reactions: the use of nuclear projectiles to convert one species of nucleus into another. If, for example, sodium is bombarded with neutrons, some of the stable ®Na₁₂ nuclei capture neutrons to form radioactive ²Na₁₃ nuclei:

®Na12 + ¦n1→²Na13 + g rays

Neutron reactions are studied by placing samples inside nuclear reactors, which produce a high neutron flux (high number of neutrons per unit area).

Nuclei can also react with each other, but being positively charged, they repel each other with great force. The projectile nucleus must have a high energy to overcome the repulsion and to react with target nuclei. High-energy nuclei are produced in cyclotrons, Van de Graaff generators, or other electronuclear accelerators. See Particle Accelerators.

A typical nuclear reaction is the one that was used to produce artificially the next heavier element above uranium (°U), the heaviest element that occurs in nature (see Periodic Law). Neptunium (°Np) was made by bombarding uranium (mostly °U) with deuterons (nuclei of the heavy hydrogen isotope, ªH₁) to knock out two neutrons, forming ±Np:

°U 146 + ªH1→±Np145 + 2¦n1