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Francium is a chemical element with the symbol Fr and atomic number 87. Prior to its discovery, it was referred to as eka-caesium. It is extremely radioactive; its most stable isotope, francium-223, has a half-life of only 22 minutes. It is the second-most electropositive element, behind only caesium, and is the second rarest naturally occurring element. The isotopes of francium decay quickly into astatine, radium, and radon. The electronic structure of a francium atom is [Rn] 7s1, and so the element is classed as an alkali metal.
Glenn Theodore Seaborg was an American chemist whose involvement in the synthesis, discovery and investigation of ten transuranium elements earned him a share of the 1951 Nobel Prize in Chemistry. His work in this area also led to his development of the actinide concept and the arrangement of the actinide series in the periodic table of the elements.
Roentgenium is a chemical element with the symbol Rg and atomic number 111. It is an extremely radioactive synthetic element that can be created in a laboratory but is not found in nature. The most stable known isotope, roentgenium-282, has a half-life of 100 seconds, although the unconfirmed roentgenium-286 may have a longer half-life of about 10.7 minutes. Roentgenium was first created in 1994 by the GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany. It is named after the physicist Wilhelm Röntgen, who discovered X-rays. Only a few roentgenium atoms have ever been synthesized, and they contain no current practical application beyond that of scientific study.
Irène Joliot-Curie was a French chemist, physicist, and a politician of partly Polish ancestry, the elder daughter of Marie Curie and Pierre Curie, and the wife of Frédéric Joliot-Curie. Jointly with her husband, Joliot-Curie was awarded the Nobel Prize in Chemistry in 1935 for their discovery of artificial radioactivity. This made the Curies the family with the most Nobel laureates to date. She was also one of the first three women to be a member of a French government, becoming undersecretary for Scientific Research under the Popular Front in 1936. Both children of the Joliot-Curies, Hélène and Pierre, are also prominent scientists.
Marguerite Catherine Perey was a French physicist and a student of Marie Curie. In 1939, Perey discovered the element francium by purifying samples of lanthanum that contained actinium. In 1962, she was the first woman to be elected to the French Académie des Sciences, an honor denied to her mentor Curie. Perey died of cancer in 1975.
Unbibium, also known as element 122 or eka-thorium, is the hypothetical chemical element in the periodic table with the placeholder symbol of Ubb and atomic number 122. Unbibium and Ubb are the temporary systematic IUPAC name and symbol respectively, which are used until the element is discovered, confirmed, and a permanent name is decided upon. In the periodic table of the elements, it is expected to follow unbiunium as the second element of the superactinides and the fourth element of the 8th period. Similarly to unbiunium, it is expected to fall within the range of the island of stability, potentially conferring additional stability on some isotopes, especially 306Ubb which is expected to have a magic number of neutrons (184).
Neptunium (93Np) is usually considered an artificial element, although trace quantities are found in nature, so a standard atomic weight cannot be given. Like all trace or artificial elements, it has no stable isotopes. The first isotope to be synthesized and identified was 239Np in 1940, produced by bombarding 238U with neutrons to produce 239U, which then underwent beta decay to 239Np.
Meitnerium (109Mt) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 266Mt in 1982, and this is also the only isotope directly synthesized; all other isotopes are only known as decay products of heavier elements. There are eight known isotopes, from 266Mt to 278Mt. There may also be two isomers. The longest-lived of the known isotopes is 278Mt with a half-life of 8 seconds. The unconfirmed heavier 282Mt appears to have an even longer half-life of 67 seconds.
Roentgenium (111Rg) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 272Rg in 1994, which is also the only directly synthesized isotope; all others are decay products of nihonium, moscovium, and tennessine, and possibly copernicium, flerovium, and livermorium. There are 7 known radioisotopes from 272Rg to 282Rg. The longest-lived isotope is 282Rg with a half-life of 2.1 minutes, although the unconfirmed 283Rg and 286Rg may have longer half-lives of about 5.1 minutes and 10.7 minutes respectively.
Moscovium (115Mc) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no known stable isotopes. The first isotope to be synthesized was 288Mc in 2004. There are four known radioisotopes from 287Mc to 290Mc. The longest-lived isotope is 290Mc with a half-life of 0.65 seconds.
Hans Kronberger CBE, FRS was a British physicist. During his career with the UK Atomic Energy Authority he made important contributions to the development of the British thermonuclear bomb and nuclear power engineering, especially in the field of isotope separation.
Aaldert Hendrik Wapstra was a Dutch physicist.
Isotopes are two or more types of atoms that have the same atomic number and position in the periodic table, and that differ in nucleon numbers due to different numbers of neutrons in their nuclei. While all isotopes of a given element have almost the same chemical properties, they have different atomic masses and physical properties.
The Commission on Isotopic Abundances and Atomic Weights (CIAAW) is an international scientific committee of the International Union of Pure and Applied Chemistry (IUPAC) under its Division of Inorganic Chemistry. Since 1899, it is entrusted with periodic critical evaluation of atomic weights of chemical elements and other cognate data, such as the isotopic composition of elements. The biennial CIAAW Standard Atomic Weights are accepted as the authoritative source in science and appear worldwide on the periodic table wall charts.
Jules Guéron was a French physical chemist and atomic scientist who played a key role in the development of atomic energy in France.
Étienne Klein is a French physicist and philosopher of science, born in 1958. A graduate of École Centrale Paris, he holds a DEA in theoretical physics, as well as a Ph.D. in philosophy of science and an accreditation to supervise research (HDR).
Iqbal Hussain Qureshi 27 September 1937 – 8 December 2012) SI, FPAS, best known as I.H. Qureshi, was a Pakistani nuclear chemist and an Emeritus professor of chemistry at the University of Karachi. Qureshi was the principal contributor of scientific understanding of various chemical elements: bismuth, cobalt, strontium, thallium, tritium, iron, rubidium, and zinc.
Karl Paley Cohen was a physical chemist who became a mathematical physicist and helped usher in the age of nuclear energy and reactor development. He began his career in 1937 making scientific advances in uranium enrichment as research assistant to Harold Urey, who discovered deuterium–the heavy isotope of hydrogen. Cohen worked within the Columbia group of physicists that included Harold Urey, Enrico Fermi, Leo Szilard, Isidor Isaac Rabi, John R. Dunning, Eugene T. Booth, A. Von Gross and others)–all pioneers of nuclear energy.
Ignace Robert Dautray, born Kouchelevitz on February 1, 1928 in the 10th arrondissement of Paris, is a French engineer, former scientific director of the French Commissariat à l'Energie Atomique (CEA) and former High Commissioner for Atomic Energy. He is a member of the French Academy of Sciences, section mechanical and computer sciences, and of the French Academy of Technology.
Vasudeva Kilara Iya is an Indian Nuclear Scientist and the First Head of the radioisotope and radiation technology programme of the Department of Atomic Energy (DAE) and a former Group Director at BARC (1974-1987).
References
- ↑ "Etienne Roth - Who's who in France".
- ↑ "Etienne Roth (1922-2009)". L'Actualité Chimique. June 2009. pp. 63–64.
- ↑ Jérôme Gaillardet, lauréat 2004 Prix Étienne Roth du CEA Jérôme Gaillardet, professeur à l’Institut de physique du globe (UMR 7154) reçoit le Prix Étienne Roth du Commissariat à l’énergie atomique pour l’année 2004.
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