Isotopes of gold

Gold (Au) has one stable isotope, ¹⁹⁷Au, and 36 radioisotopes with ¹⁹⁵Au being the most stable with a half-life of 186 days.

Gold is currently considered the heaviest monoisotopic element (Bismuth formerly held that distinction, but Bismuth-209 has been found to be slightly radioactive).

Standard atomic mass: 196.966569(4) u

Radioactive particle tracking

Inside coker units at oil refineries, Gold-198 is used to study the hydrodynamic behavior of solids in fluidized beds and can also be used to quantify the degree of fouling of bed internals.^[1]

Nuclear medicine

Gold-198 is a beta emitter with range in tissue of about 11 mm and half life 2.7 days. It is used in some cancer treatments and for treating other diseases.^[2][3] Gold-198 nanoparticles are being investigated as an injectable treatment for prostate cancer.^[4]

Nuclear weapons

Gold has been proposed as a material for creating a salted nuclear weapon (cobalt is another, better-known salting material). A jacket of natural ¹⁹⁷Au, irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, would transmute into the radioactive isotope ¹⁹⁸Au with a half-life of 2.697 days and produce approximately .411 MeV of gamma radiation, significantly increasing the radioactivity of the weapon's fallout for several days. Such a weapon is not known to have ever been built, tested, or used.^[5] Gold has been used in thermonuclear weapons as radiation mirrors within the secondary assembly. Ivy Mike used a thin layer of gold on the secondary casing walls to enhance the blackbody effect, trapping more energy in the foam to enhance the implosion.^[6]

The highest amount of ¹⁹⁸Au detected in any United States nuclear test was in shot "Sedan" detonated at Nevada Test Site on July 6, 1962.^[7]

Table

1. ↑ Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
2. ↑ Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe)
3. ↑ Potential material for salted bombs
4. ↑ Believed to undergo α decay to ¹⁹³Ir

Notes

• Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
• Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

References

• Isotope masses from:
  • G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties". Nuclear Physics A 729 (1): 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. 
• Isotopic compositions and standard atomic masses from:
  • J. R. de Laeter, J. K. Böhlke, P. De Bièvre, H. Hidaka, H. S. Peiser, K. J. R. Rosman and P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry 75 (6): 683–800. doi:10.1351/pac200375060683. 
  • M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary. 
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
  • G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties". Nuclear Physics A 729 (1): 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. 
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005. 
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9.