There are 39 known isotopes and 17 nuclear isomers of tellurium (52Te), with atomic masses that range from 104 to 142.
Several nuclear isomers have longer half-lives, the longest being 121mTe with a half-life of 154 days.
It has been claimed that electron capture of 123Te was observed, but more recent measurements of the same team have disproved this.
[6] 124Te can be used as a starting material in the production of radionuclides by a cyclotron or other particle accelerators.
The short-lived isotope 135Te (half-life 19 seconds) is produced as a fission product in nuclear reactors.