197Aun198Au

197Aun198Au refers to the pair of gold isotopes with mass numbers 197 and 198. The 197Au isotope is stable, while 198Au is radioactive. These two isotopes illustrate the contrast between a natural, non-decaying nuclide and a synthetic radioisotope created in reactors or accelerators.

197Au is the only stable isotope of gold and makes up essentially all natural gold. It remains stable on geological timescales and is widely studied in physics and chemistry as the reference isotope for gold. Its stability underpins its long-standing commercial use in jewelry, electronics, and various industrial applications.

198Au is a radioisotope with a half-life of about 2.69 days. It decays via beta-minus emission to 198Hg and often emits gamma radiation as well. 198Au is not found in nature and is produced artificially, typically by neutron irradiation of 197Au in a nuclear reactor or through other accelerator-based production routes. It has historical and contemporary applications as a radiotracer and as a gamma source in medical and industrial contexts, including radiography and brachytherapy, though its use requires careful handling due to radioactivity.

In summary, 197Au is the stable, natural form of gold, while 198Au provides a controllable radioactive isotope useful for various diagnostic and therapeutic purposes, reflecting the practical relevance of gold’s isotopes in science and industry.