Technetium is a silver-gray radioactive element and is found in D block with an atomic number of 43. Most Tc-99 is produced synthetically, where natural occurrences of the element are rarely formed from the fission of uranium in the earth's crust. Tc-99 is the most common isotope with a radioactive half-life of 212,000 years and can be found primarily in nuclear reactors. Technetium was originally discovered by three German chemists, Ida Noddack-Tacke, Walter Noddack and Otto Berg, who had published a paper claiming the discovery of "Masurium" in 1925, however at the time being unable to verify its existence of "Masurium", the International Union of Pure and Applied Chemistry ruled out its discovery. Masurium was believed to be presumably technetium due to the very similar chemical properties and atomic number. Technetium was later discovered and demonstrated in the form of technetium-97 by two research assistants at the University of California at Berkeley, Emilio Segre and Carlo Perrier. In 1937 the discovery originated from a sample of mol...