Atomic number: 43
Year discovered: 1937
Discovered by: Emilio Gino Segré (1905-1989), an Italian physicist, and Carlo Perrier of Italy.
- Element 43 (technetium) was predicted on the basis of the periodic table by Mendeléyev.
- He suggested that it should be very similar to manganese and gave it the name eka-manganese.
- Technetium was erroneously reported as having been discovered in 1925, at which time it was named masurium.
- The element was actually discovered by C. Perrier and Emilio Gino Segrè in Italy in 1937.
- It was found in a sample of molybdenum bombarded by deuterons.
- Technetium was the first element to be produced artificially and all its isotopes are radioactive.
- It is named after the Greek word technetos, meaning "artificial".
In the February, 2000, issue of Scientific American, page 9, there is an article titled, “An Elemental Mystery” (Who really discovered element 43?) by Alden M. Hayashi in which he states that In 1925 German chemist Ida Tacke and her colleagues Walter Noddack, who would become her husband; and Otto Berg made a stunning announcement:
- Using x-ray spectroscopy, they had reportedly discovered element 43, which they named masurium.
- Ernest O. Lawrence, the Nobel Prize-winning physicist, called the masurium investigators “apparently deluded.”
- As stated earlier, credit for the discovery of element 43 went to Carlo Perrier and Emilio Segré in 1937, which they named technetium.
- The Noddack team fired a beam of electrons at different materials, inducing them to emit x-rays.
- With this technique, Noddack and her colleagues analyzed columbite ores—a black mineral consisting of niobium—and obtained faint x-ray spectral lines that appeared to correspond to the radioactive element 43.
- “I thought it was impossible that they had discovered technetium. But after looking more closely into it, I decided that you couldn’t automatically throw out their claim,” says Albert Ghiorso of Lawrence Berkeley National Laboratory.
- Ghiorso, by the way, worked with Glenn T. Seaborg to discover several of the transuranic elements that had eluded Enrico Fermi who thought he had synthesized transuranic elements and even won a Nobel Prize for his supposed discovery of transuranic elements.
- So what we have here is a strong possibility that German chemist Ida Tacke, with Walter Noddack and Otto Berg, actually discovered element 43 in 1925, twelve years before the claim made by Carlo Perrier and Emilio Segré.
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Information about other elements may be seen at this Chemical Elements List.
A special unit about words that include chemo-, chem- may be seen here.