High Quality Content by WIKIPEDIA articles! Technetium (abbreviation Tc, atomic number 43) is the first of the two elements in the first 82 that have no stable isotopes (all are radioactive); the other such element is promethium. It is primarily artificial, only trace quantities existing in nature produced by spontaneous fission or neutron capture by molybdenum. The first isotopes to be synthesized were 97Tc and 99Tc in 1936, the first artificial element to be produced. The most stable radioisotopes are 98Tc (half-life of 4.2 million years), 97Tc (half-life: 2.6 million years) and 99Tc (half-life: 211.1 thousand years).