Walter Noddack
Encyclopedia
Walter Noddack was a German chemist. He, Ida Tacke (who later married Noddack), and Otto Berg
reported the discovery of element 43
and element 75
in 1925.
Rhenus meaning "Rhine"). Rhenium was the next-to-last naturally occurring element to be discovered and the last element to be discovered having a stable isotope. The existence of a yet undiscovered element at this position in the periodic table
had been predicted by Henry Moseley
in 1914. In 1925 they reported that they detected the element in platinum ore and in the mineral columbite
. They also found rhenium in gadolinite
and molybdenite
. In 1928 they were able to extract 1 g of the element by processing 660 kg of molybdenite.
in Eastern Prussia). The group bombarded columbite with a beam of electron
s and deduced element 43 was present by examining X-ray
diffraction spectrogram
s. The wavelength
of the X-rays produced is related to the atomic number by a formula derived by Henry Moseley
. The team claimed to detect a faint X-ray signal at a wavelength produced by element 43. Contemporary experimenters could not replicate the discovery, and in fact it was dismissed as an error for many years.
It was not until 1998 that this dismissal began to be questioned. John T. Armstrong of the National Institute of Standards and Technology
ran computer simulations of the experiments and obtained results very close to those reported by the 1925 team; the claim was further supported by work published by David Curtis of the Los Alamos National Laboratory
measuring the (tiny) natural occurrence of technetium. Debate still exists as to whether the 1925 team actually did discover element 43.
and 1941 at the Reichsuniversität Straßburg
. After World War II
he changed to the University of Bamberg and in 1956 he became director of the newly founded Research Institute for geochemistry
there.
Otto Berg (scientist)
Otto Berg was a German scientist. He is one of the scientists credited with discovering rhenium, the next-to-last naturally occurring element to be discovered and the last element to be discovered having a stable isotope.-Rhenium:...
reported the discovery of element 43
Technetium
Technetium is the chemical element with atomic number 43 and symbol Tc. It is the lowest atomic number element without any stable isotopes; every form of it is radioactive. Nearly all technetium is produced synthetically and only minute amounts are found in nature...
and element 75
Rhenium
Rhenium is a chemical element with the symbol Re and atomic number 75. It is a silvery-white, heavy, third-row transition metal in group 7 of the periodic table. With an average concentration of 1 part per billion , rhenium is one of the rarest elements in the Earth's crust. The free element has...
in 1925.
Rhenium
They named element 75 rhenium (LatinLatin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
Rhenus meaning "Rhine"). Rhenium was the next-to-last naturally occurring element to be discovered and the last element to be discovered having a stable isotope. The existence of a yet undiscovered element at this position in the periodic table
Periodic table
The periodic table of the chemical elements is a tabular display of the 118 known chemical elements organized by selected properties of their atomic structures. Elements are presented by increasing atomic number, the number of protons in an atom's atomic nucleus...
had been predicted by Henry Moseley
Henry Moseley
Henry Gwyn Jeffreys Moseley was an English physicist. Moseley's outstanding contribution to the science of physics was the justification from physical laws of the previous empirical and chemical concept of the atomic number. This stemmed from his development of Moseley's law in X-ray spectra...
in 1914. In 1925 they reported that they detected the element in platinum ore and in the mineral columbite
Columbite
Columbite, also called niobite, niobite-tantalite and columbate [2O6], is a black mineral group that is an ore of niobium and tantalum. It has a submetallic luster and a high density and is a niobate of iron and manganese, containing tantalate of iron. This mineral group was first found in Haddam,...
. They also found rhenium in gadolinite
Gadolinite
Gadolinite, sometimes also known as Ytterbite, is a silicate mineral which consists principally of the silicates of cerium, lanthanum, neodymium, yttrium, beryllium, and iron with the formula 2FeBe2Si2O10...
and molybdenite
Molybdenite
Molybdenite is a mineral of molybdenum disulfide, MoS2. Similar in appearance and feel to graphite, molybdenite has a lubricating effect that is a consequence of its layered structure. The atomic structure consists of a sheet of molybdenum atoms sandwiched between sheets of sulfur atoms...
. In 1928 they were able to extract 1 g of the element by processing 660 kg of molybdenite.
Technetium
Element 43 was named masurium (after MasuriaMasuria
Masuria is an area in northeastern Poland famous for its 2,000 lakes. Geographically, Masuria is part of two adjacent lakeland districts, the Masurian Lake District and the Iława Lake District...
in Eastern Prussia). The group bombarded columbite with a beam of electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s and deduced element 43 was present by examining X-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
diffraction spectrogram
Spectrogram
A spectrogram is a time-varying spectral representation that shows how the spectral density of a signal varies with time. Also known as spectral waterfalls, sonograms, voiceprints, or voicegrams, spectrograms are used to identify phonetic sounds, to analyse the cries of animals; they were also...
s. The wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
of the X-rays produced is related to the atomic number by a formula derived by Henry Moseley
Henry Moseley
Henry Gwyn Jeffreys Moseley was an English physicist. Moseley's outstanding contribution to the science of physics was the justification from physical laws of the previous empirical and chemical concept of the atomic number. This stemmed from his development of Moseley's law in X-ray spectra...
. The team claimed to detect a faint X-ray signal at a wavelength produced by element 43. Contemporary experimenters could not replicate the discovery, and in fact it was dismissed as an error for many years.
It was not until 1998 that this dismissal began to be questioned. John T. Armstrong of the National Institute of Standards and Technology
National Institute of Standards and Technology
The National Institute of Standards and Technology , known between 1901 and 1988 as the National Bureau of Standards , is a measurement standards laboratory, otherwise known as a National Metrological Institute , which is a non-regulatory agency of the United States Department of Commerce...
ran computer simulations of the experiments and obtained results very close to those reported by the 1925 team; the claim was further supported by work published by David Curtis of the Los Alamos National Laboratory
Los Alamos National Laboratory
Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...
measuring the (tiny) natural occurrence of technetium. Debate still exists as to whether the 1925 team actually did discover element 43.
Academic career
Noddack became professor for physical chemistry in 1935 at the University of FreiburgUniversity of Freiburg
The University of Freiburg , sometimes referred to in English as the Albert Ludwig University of Freiburg, is a public research university located in Freiburg im Breisgau, Baden-Württemberg, Germany.The university was founded in 1457 by the Habsburg dynasty as the...
and 1941 at the Reichsuniversität Straßburg
Reichsuniversität Straßburg
The Reichsuniversität Straßburg was founded 1941 by the National Socialists in Alsace while the regular University of Strasbourg had moved to Clermont-Ferrand since 1940. The purpose was to create a continuity to the German character of the German Imperial University of Strasbourg, that had been...
. After World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
he changed to the University of Bamberg and in 1956 he became director of the newly founded Research Institute for geochemistry
Geochemistry
The field of geochemistry involves study of the chemical composition of the Earth and other planets, chemical processes and reactions that govern the composition of rocks, water, and soils, and the cycles of matter and energy that transport the Earth's chemical components in time and space, and...
there.