Unstable elements

Rowland, L.J. Strommer, J.N. (1985). Insertion of an unstable element in an intervening sequence of maize AdhI affects transcription but not processing. Proceedings of the National Academy of Sciences, USA, 82, 2875-9. 

Clearly, the person who ordered element q was not a chemist, because the unstable element would have decayed long before its arrival. 

The controller function will take on a positive pole if the process function has a positive zero. It is not desirable to have an inherently unstable element in our control loop. This is an issue which internal model control will address. 

Like einsteinium, this unstable element was discovered in the fallout from the first hydrogen bomb. To date, only fragments in microgram amounts can be isolated. 258Fm ends the series of transuranium elements that can be produced in a reactor by neutron bombardment. The longest-lived isotope decays with a half-life of 100 days... 

Progress in understanding stellar evolution and nucleosynthesis, and the discovery by Merrill (1952) of the unstable element technetium in the S star R Andromedae, demonstrating the occurrence of stellar nucleosynthesis within a few half-lives of Tc (i.e. < about 1 Myr see Fig. 1.8), has led to acceptance of the idea that abundance variations among stars are perfectly natural as a consequence of three main effects (see Fig. 3.37) ... 

Lanthanide series of elements. The longest half-life associated with this unstable element is 7370 year Am. 

Astatine - the atomic number is 85 and the chemical symbol is At. The name derives from the Greek astatos for unstable since it is an unstable element. It was first thought to have been discovered in nature in 1931 and was named alabamine. When it was determined that there are no stable nuclides of this element in nature, that claim was discarded. It was later shown that astatine had been synthesized by the physicists Dale R. Corson, K. R. Mackenzie and Emilio Segre at the University of California lab in Berkeley, California in 1940 who bombarded bismuth with alpha particles, in the reaction Bi ( He, 2n ) "At. Independently, a claim about finding some x-ray lines of astatine was the basis for claiming discovery of an element helvetium, which was made in Bern, Switzerland. However, the very short half-life precluded any chemical separation and identification. The longest half-life associated with this unstable element is 8.1 hour °At. 

Bohrium - the atomic number is 107 and the chemical symbol is Bh. The name derives from the Danish physicist Niels Bohr, who developed the theory of the electronic structure of the atom. The first synthesis of this element is eredited to the laboratory of the GSI (Center for Heavy-Ion Research) under the leadership of the German scientists Peter Armbruster and Gunther Mhnzenberg at Darmstadt, Germany in 1981, using the reaction ° Bi ( Cr, n) Bh. The longest half-life associated with this unstable element is 17 second Bh. 

California under Gleim T. Seaborg used the nuclear reaction Cm ( He, n) Cf to first detect the element californium in 1950. The longest half-life associated with this unstable element is 900 year Cf. 

Element 110 - no name has been proposed or accepted by lUPAC for element 110. This element was first synthesized in a November 1994 experiment by a multi-national team of scientists working at the Gesellschaft fur Schwerionenforschung (GSI) in Darmstadt, Germany. The scientific teams were from the GSI (Heavy Ion Research Center), Darmstadt, the Joint Institute for Nuclear Research (JINR), Dubna, Russia, Comenius University, Bratislava, Slovakia and the University of Jyvaskyla, Finland. They used the nuclear reaction ° Pb ( Ni, n) 110. The longest half-life associated vdth this unstable element is 1.1 minute 10. 

Fermium - the atomic number is 100 and the chemical symbol is Fm. The name derives from the Italian bom physicist Enrico Fermi , who built the first man made nuclear reactor. The nuchde Fm was found in the debris of a thermonuclear weapon s explosion in 1952 by a collaboration of American scientists from the Argonne National Laboratory near Chicago, Illinois, the Los Alamos Scientific Laboratory in Los Alamos, New Mexico and the University of California lab at Berkeley, California. The longest half-life associated with this unstable element is 100 day... 

Francium - the atomic number is 87 and the chemical symbol is Fr. The name derives from the country France , where the French physicist Marguerite Percy from the Curie Institute in Paris, France discovered it in 1939 in the alpha particle decay of actinium, Ac => He => Fr, which was known as actinium-K and has a half-life of 22 minutes. An earlier claim of discovery in 1930 with the element name Virginium was determined to be incorrect. A similar claim for discovery of the element with atomic number 87 and named moldavium was also determined to be incorrect. The longest half-life associated with this unstable element is 22 minute Fr. 

Lawrencium - the atomic number is 103 and the chemical symbol is Lr. The original chemical symbol was proposed as Lw but it was changed because W is an unusual occurrence in many languages and it is a cumbersome spoken word. The name derives from the American physicist Ernest O. Lawrence , who developed the cyclotron. Credit for the first synthesis of this element in 1971 is given jointly to American chemists from the University of California laboratory in Berkeley, California under Albert Ghiorso and the Russian scientific team at the JINR (Joint Institute for Nuclear Reactions) lab in Dubna, Russia under Georgi N. Flerov, after a series of preliminary papers presented over a decade. The longest half-life associated with this unstable element is 3.6 hour Lr. 

Plutonium - the atomic number is. 94 and the chemical symbol is Pu. The name derives from the planet Pluto, (the Roman god of the underworld). Pluto was selected because it is the next planet in the solar system beyond the planet Neptime and the element plutonium is the next element in the period table beyond neptunium. Plutonium was first synthesized in 1940 by American chemists Glenn T. Seaborg, Edwin M. McMillan, Joseph W. Kennedy and Arthur C. Wahl in the nuclear reaction U( H, 2n) Np = P => Pu. The longest half-life associated with this unstable element is 80 million year Pu. 

Polonium - the atomic number is 84 and the chemical symbol is Po. This radioactive metal was also known as radium-F. The name derives from Poland , the native country of Marie Sklodowska Curie. It was discovered by Pierre and Marie Curie in 1898, from its radioactivity. It was independently found by the German chemist Willy Marckwald in 1902 and called radiotellurium. The longest half-life associated with this unstable element is 102 year ° Po. 

ISOTOPES There are no stable isotopes of francium found on Earth. All of its 33 isotopes (ranging from Fr-201 to Fr-232) are radioactive therefore, the one with the longest half-life of about 20 minutes (Fr-223) is the one used to determine its atomic weight. Fr-223 is the only radioisotope of francium that is found naturally as a decay product from other unstable elements. 

When the French chemist Antoine Lavoisier published his famous list of elements in 1789, there were only 33 elements, several of which were erroneous. By 1930, the diligent labors of thousands of chemists had increased the tally of naturally occurring chemical elements to 90. More recently, physicists in high-energy laboratories have been able to create about 20 highly radioactive, unstable elements that do not exist naturally on Earth, although they are probably produced in the hot cores of some stars. 

All the E values are measured, but these are rather approximate values since At is an unstable element and rather dilute solutions (c 10 mol dm ) are used to test the redox properties. 

Uranium-238 emits an alpha particle to become an isotope of thorium. This unstable element emits a beta particle to become the element now known as Protactinium (Pa), which then emits another beta particle to become an isotope of uranium. This chain proceeds through another isotope of thorium, through radium, radon, polonium, bismuth, thallium and lead. The final product is lead-206. The series that starts with thorium-232 ends with lead-208. Soddy was able to isolate the different lead isotopes in high enough purity to demonstrate using chemical techniques that the atomic weights of two samples of lead with identical chemical and spectroscopic properties had different atomic weights. The final picture of these elements reveals that there are several isotopes for each of them. 

In order to end up with an element that was not in the reactants, the particles in the nucleus of an atom—the protons and neutrons—would have to change. This is a different type of reaction, called a nuclear reaction. Some nuclear reactions occur naturally in elements that are described as radioactive. The nuclei of radioactive elements are unstable. Since they are unstable, they can fall apart and give off subatomic particles. Eventually, through a process called radioactive decay, these unstable elements are transformed into a stable (non-radioactive) element. When an atom of one element is changed into an atom of another element through a nuclear reaction, it is called transmutation. 

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