 | |
| General | |
|---|---|
| Symbol | 99Tc |
| Names | technetium-99, 99Tc, Tc-99 |
| Protons (Z) | 43 |
| Neutrons (N) | 56 |
| Nuclide data | |
| Natural abundance | trace |
| Half-life (t1/2) | 211100±1200 years |
| Spin | 9/2+ |
| Excess energy | −87327.9±0.9 keV |
| Binding energy | 8613.610±0.009 keV |
| Decay products | 99Ru |
| Decay modes | |
| Decay mode | Decay energy (MeV) |
| Beta decay | 0.2975 |
| Isotopes of technetium Complete table of nuclides | |
Technetium-99 (99Tc) is an isotope of technetium which decays with a half-life of 211,000 years to stable ruthenium-99, emitting beta particles, but no gamma rays. It is the most significant long-lived fission product of uranium fission, producing the largest fraction of the total long-lived radiation emissions of nuclear waste. Technetium-99 has a fission product yield of 6.0507% for thermal neutron fission of uranium-235.
The metastable technetium-99m (99mTc) is a short-lived (half-life about 6 hours) nuclear isomer used in nuclear medicine, produced from molybdenum-99. It decays by isomeric transition to technetium-99, a desirable characteristic, since the very long half-life and type of decay of technetium-99 imposes little further radiation burden on the body.