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Mattauch Isobar Rule
The Mattauch isobar rule, formulated by Josef Mattauch in 1934, states that if two adjacent chemical element, elements on the periodic table have isotopes of the same mass number, one of these isotopes must be radioactivity, radioactive. Two nuclides that have the same mass number (isobar (nuclide), isobars) can both be stable only if their atomic numbers differ by more than one. In fact, for currently observationally stable nuclides, the difference can only be 2 or 4, and in theory, two nuclides that have the same mass number cannot be both stable (at least to beta decay or double beta decay), but many such nuclides which are theoretically unstable to double beta decay have not been observed to decay, e.g. 134Xe. However, this rule cannot make predictions on the half-life, half-lives of these radioisotopes. Technetium and promethium A consequence of this rule is that technetium and promethium both have no stable isotopes, as each of the neighboring elements on the periodic table (mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Josef Mattauch
Josef Mattauch (21 November 1895 – 10 August 1976) was a nuclear physicist and chemist. He was known for the development of the Mattauch-Herzog double-focusing mass spectrometer, for his work on the investigation of isotopic abundances using mass spectrometry, and the determination of atomic weights. Much of his career was spent at the Kaiser Wilhelm Institute for Chemistry (later the Max Planck Institute). He developed the Mattauch isobar rule ("Isobarenregel") in 1934. He correctly predicted that the last of the rare earth elements, element 61 (later named promethium), would not have stable isotopes. Early life Josef Heinrich Elisabeth Mattauch was born 21 November 1895 in Ostrau, Moravia. Mattauch was educated at the University of Vienna, where he worked with Felix Ehrenhaft. Ehrenhaft believed he had discovered a "sub-electron", smaller than anything measured by Robert Andrews Millikan. Mattauch's results, however, were in agreement with Millikan and not Ehrenhaft. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radioisotope
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferred to one of its electrons to release it as a conversion electron; or used to create and emit a new particle (alpha particle or beta particle) from the nucleus. During those processes, the radionuclide is said to undergo radioactive decay. These emissions are considered ionizing radiation because they are energetic enough to liberate an electron from another atom. The radioactive decay can produce a stable nuclide or will sometimes produce a new unstable radionuclide which may undergo further decay. Radioactive decay is a random process at the level of single atoms: it is impossible to predict when one particular atom will decay. However, for a collection of atoms of a single nuclide the decay rate, and thus the half-life (''t''1/2) for t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Wiley & Sons
John Wiley & Sons, Inc., commonly known as Wiley (), is an American multinational publishing company founded in 1807 that focuses on academic publishing and instructional materials. The company produces books, journals, and encyclopedias, in print and electronically, as well as online products and services, training materials, and educational materials for undergraduate, graduate, and continuing education students. History The company was established in 1807 when Charles Wiley opened a print shop in Manhattan. The company was the publisher of 19th century American literary figures like James Fenimore Cooper, Washington Irving, Herman Melville, and Edgar Allan Poe, as well as of legal, religious, and other non-fiction titles. The firm took its current name in 1865. Wiley later shifted its focus to scientific, technical, and engineering subject areas, abandoning its literary interests. Wiley's son John (born in Flatbush, New York, October 4, 1808; died in East Orange, New Je ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Q Value (nuclear Science)
In nuclear physics and chemistry, the value for a reaction is the amount of energy absorbed or released during the nuclear reaction. The value relates to the enthalpy of a chemical reaction or the energy of radioactive decay products. It can be determined from the masses of reactants and products. values affect reaction rates. In general, the larger the positive value for the reaction, the faster the reaction proceeds, and the more likely the reaction is to "favor" the products. : Q = (\,m_\text - m_\text\,) \times \text where the masses are in atomic mass units. Also both \;m_\text\; and \;m_\text\; are the sums of the reactant and product masses respectively. Definition The conservation of energy, between the initial and final energy of a nuclear process \text E_\text = E_\text \text enables the general definition of based on the mass–energy equivalence. For any radioactive particle decay, the kinetic energy difference will be given by: : Q = K_\text - K_\text = (\ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Energy Conservation
Energy conservation is the effort to reduce wasteful energy consumption by using fewer energy services. This can be done by using energy more effectively (using less energy for continuous service) or changing one's behavior to use less service (for example, by driving less). Energy conservation can be achieved through energy efficiency, which has a number of advantages, including a reduction in greenhouse gas emissions, a smaller carbon footprint, and cost, water, and energy savings. Energy conservation is an essential factor in building design and construction. It has increased in importance since the 1970s, as 40% of energy use in the U.S. is in buildings. Recently, concern over the effects of climate change and global warming has emphasized the importance of energy conservation. Energy can only be transformed from one form to another, such as when heat energy is converted into vehicle motive power or when water flow's kinetic energy is converted into electricity in hydroelectr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Binding Energy
Nuclear binding energy in experimental physics is the minimum energy that is required to disassemble the atomic nucleus, nucleus of an atom into its constituent protons and neutrons, known collectively as nucleons. The binding energy for stable nuclei is always a positive number, as the nucleus must gain energy for the nucleons to move apart from each other. Nucleons are attracted to each other by the strong nuclear force. In theoretical nuclear physics, the nuclear binding energy is considered a negative number. In this context it represents the energy of the nucleus relative to the energy of the constituent nucleons when they are infinitely far apart. Both the experimental and theoretical views are equivalent, with slightly different emphasis on what the binding energy means. The mass of an atomic nucleus is less than the sum of the individual masses of the free Wiktionary:constituent, constituent protons and neutrons. The difference in mass can be calculated by the Mass–energ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass Excess
The mass excess of a nuclide is the difference between its actual mass and its mass number in daltons. It is one of the predominant methods for tabulating nuclear mass. The mass of an atomic nucleus is well approximated (less than 0.1% difference for most nuclides) by its mass number, which indicates that most of the mass of a nucleus arises from mass of its constituent protons and neutrons. Thus, the mass excess is an expression of the nuclear binding energy, relative to the binding energy per nucleon of carbon-12 (which defines the dalton). If the mass excess is negative, the nucleus has more binding energy than 12C, and vice versa. If a nucleus has a large excess of mass compared to a nearby nuclear species, it can radioactively decay, releasing energy. Energy scale of nuclear reactions The 12C standard provides a convenient unit (the dalton) in which to express nuclear mass for defining the mass excess. However, its usefulness arises in the calculation of nuclear reaction kinema ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotopes Of Technetium
Technetium (43Tc) is one of the two elements with that have no stable isotopes; the other such element is promethium. – Elements marked with a * have no stable isotope: 43, 61, and 83 and up. It is primarily artificial, with only trace quantities existing in nature produced by spontaneous fission (there are an estimated grams of 99Tc per gram of pitchblende) or neutron capture by molybdenum. The first isotopes to be synthesized were 97Tc and 99Tc in 1936, the first artificial element to be produced. The most stable radioisotopes are 97Tc (half-life of 4.21 million years), 98Tc (half-life: 4.2 million years), and 99Tc (half-life: 211,100 years). Thirty-three other radioisotopes have been characterized with atomic masses ranging from 85Tc to 120Tc. Most of these have half-lives that are less than an hour; the exceptions are 93Tc (half-life: 2.75 hours), 94Tc (half-life: 4.883 hours), 95Tc (half-life: 20 hours), and 96Tc (half-life: 4.28 days). Technetium also has numero ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid Drop Model
In nuclear physics, the semi-empirical mass formula (SEMF) (sometimes also called the Weizsäcker formula, Bethe–Weizsäcker formula, or Bethe–Weizsäcker mass formula to distinguish it from the Bethe–Weizsäcker process) is used to approximate the mass and various other properties of an atomic nucleus from its number of protons and neutrons. As the name suggests, it is based partly on theory and partly on empirical measurements. The formula represents the liquid-drop model proposed by George Gamow, which can account for most of the terms in the formula and gives rough estimates for the values of the coefficients. It was first formulated in 1935 by German physicist Carl Friedrich von Weizsäcker, and although refinements have been made to the coefficients over the years, the structure of the formula remains the same today. The formula gives a good approximation for atomic masses and thereby other effects. However, it fails to explain the existence of lines of greater binding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Samarium
Samarium is a chemical element with symbol Sm and atomic number 62. It is a moderately hard silvery metal that slowly oxidizes in air. Being a typical member of the lanthanide series, samarium usually has the oxidation state +3. Compounds of samarium(II) are also known, most notably the monoxide SmO, monochalcogenides SmS, SmSe and SmTe, as well as samarium(II) iodide. The last compound is a common reducing agent in chemical synthesis. Samarium has no significant biological role, and some samarium salts are slightly toxic. Samarium was discovered in 1879 by French chemist Paul-Émile Lecoq de Boisbaudran and named after the mineral samarskite from which it was isolated. The mineral itself was named after a Russian mine official, Colonel Vassili Samarsky-Bykhovets, who thus became the first person to have a chemical element named after him, albeit indirectly. Though classified as a rare-earth element, samarium is the 40th most abundant element in Earth's crust and more common than ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neodymium
Neodymium is a chemical element with the symbol Nd and atomic number 60. It is the fourth member of the lanthanide series and is considered to be one of the rare-earth metals. It is a hard, slightly malleable, silvery metal that quickly tarnishes in air and moisture. When oxidized, neodymium reacts quickly producing pink, purple/blue and yellow compounds in the +2, +3 and +4 oxidation states. It is generally regarded as having one of the most complex spectra of the elements. Neodymium was discovered in 1885 by the Austrian chemist Carl Auer von Welsbach, who also discovered praseodymium. It is present in significant quantities in the minerals monazite and bastnäsite. Neodymium is not found naturally in metallic form or unmixed with other lanthanides, and it is usually refined for general use. Neodymium is fairly common—about as common as cobalt, nickel, or copper—and is widely distributed in the Earth's crust. Most of the world's commercial neodymium is mined in China, as is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ruthenium
Ruthenium is a chemical element with the Symbol (chemistry), symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most other chemicals. Russian-born scientist of Baltic-German ancestry Karl Ernst Claus discovered the element in 1844 at Kazan State University and named ruthenium in honor of Russian Empire, Russia. Ruthenium is usually found as a minor component of platinum ores; the annual production has risen from about 19 tonnes in 2009Summary. Ruthenium platinum.matthey.com, p. 9 (2009) to some 35.5 tonnes in 2017. Most ruthenium produced is used in wear-resistant electrical contacts and thick-film resistors. A minor application for ruthenium is in platinu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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