Transuranic+Elements+-+Prayush+Singh


 * __Transuranic Elements__ ** By Prayush Singh

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=Overview= Transuranic elements are the elements with an atomic number greater than 92. All transuranic elements are radioactive, have short half-lives, and are not naturally present on earth. These elements were first created in laboratories through atomic reactions. A half-life is defined as the period of time it takes for a substance undergoing decay to decrease by half. Because of their extremely short half-lives, it is impossible to know whether they existed on earth at some point in time because they would have decayed into other elements without leaving a trace. Transuranic elements are created mostly as a by product in nuclear reactors or in particle accelerators for research purposes. Some of them, such as californium, can also be created by bombarding other transuranic elements with alpha particles. They have a general trend of having shorter half-lifes as the atomic number increases. Heavy transuranic elements are difficult and expensive to produce, and their prices go up rapidly with atomic number. As of 2008, weapons-grade plutonium cost around $4,000/gram and californium cost $60,000,000/gram. Due to production difficulties, none of the elements beyond californium have industrial applications or were ever produced in large quantities.



=List of Transuranic Elements= Below is a table with information on all the known transuranic elements



|| Symbol

|| Atomic Name

|| Atomic Weight

|| Density

|| Melting Point (K) || Boiling Point (K) || Electronegativity || Half Life of Longest Living Isotope ||
 * 93 || Np || Neptunium || 237.0482 || 20.45 || 913.15 || 4273 || 1.36 || 80.8 million years ||
 * 94 || Pu || Plutonium || 244.0642 || 19.84 || 913.15 || 3501 || 1.28 || 80.8 million years ||
 * 95 || Am || Americium || 243.0614 || 13.69 || 1267.15 || 2880 || 1.3 || 7370 years ||
 * 96 || Cm || Curium || 247.0704 || 13.51 || 1340.15 || 3383 || 1.3 || 9000 years ||
 * 97 || Bk || Berkelium || 247.0703 || 14.79 || 1259.15 || 983 || 1.3 || 1380 years ||
 * 98 || Cf || Californium Californium || 251.0796 || 15.1 || 1925.15 || 1173 || 1.3 || 898 years ||
 * 99 || Es || Einsteinium || 252.0829 || 13.5 || 1133.15 || - || 1.3 || 471.7 days ||
 * 100 || Fm || Fermium || 257.0951 || - || - || - || 1.3 || 101 Days ||
 * 101 || Md || Mendelevium || 258.0986 || - || - || - || 1.3 || 52 Days ||
 * 102 || No || Nobelium || 259.1009 || - || - || - || 1.3 || 58 Minutes ||
 * 103 || Lr || Lawrencium || 264 || 9.84 || - || - || - || 3.6 3.6 Hours ||
 * 104 || Rf || Rutherfordium || 265 || 18.1 || - || - || - || 1.3 Hours ||
 * 105 || Db || Dubnium || 268 || 39 || - || - || - || 29 Hours ||
 * 106 || Sg || Seaborgium || 272 || 35 || - || - || - || 1.9 Minutes ||
 * 107 || Bh || Bohrium || 273 || 37 || - || - || - || 61 Seconds ||
 * 108 || Hs || Hassium || 276 || 41 || - || - || - || 16.5 Minutes ||
 * 109 || Mt || Meitnerium || 279 || 35 || - || - || - || 8 Seconds ||
 * 110 || Ds || Darmstadtium || 278 || 21.46 || - || - || - || 11 Seconds ||
 * 111 || Rg || Roentgenium || 283 || 19.282 || - || - || - || 22.8 Seconds ||
 * 112 || Cn || Copernicium || 285 || 13.5336 || - || - || - || 29 Seconds ||
 * 113 || Uut || Ununtrium || 287 || 11.85 || - || - || - || 19.6 Seconds ||
 * 114 || Uuq || Ununquadium || 289 || 11.342 || - || - || - || 2.6 Seconds ||
 * 115 || Uup || Ununpentium || 291 || 9.807 || - || - || - || 220 Milliseconds ||
 * 116 || Uuh || Ununhexium || 293 || 9.32 || - || - || - || 61 Milliseconds ||
 * 117 || Uuh || Ununseptium || - || - || - || - || - || 78 Milliseconds ||
 * 118 || Uuo || Ununoctium ||  ||   ||   ||   ||   || 0.89 Milliseconds ||

Super heavy atoms are the transactinide elements beginning with rutherfordium. They have only been made artificially, and currently serve no useful purpose because their short half-lives cause them to decay after a few minutes to just a few milliseconds, which also makes them extremely hard to study. Super-heavy atoms have all been created during the latter half of the 20th century and are continually being created during the 21st century as technology advances. They are all created through the bombardment of elements in a particle accelerator.

=Island of Stability= Glenn T Seaborg, an american scientist who won the 1951 nobel prize for " discoveries in the chemistry of the transuranic elements" hypothesized the island of stability. The hypothesis is that the atomic nucleus is built up in "shells" in a manner similar to the electron shells in atoms. In both cases shells are just groups of quantum energy levels that are relatively close to each other. Energy levels from quantum states in two different shells will be separated by a relatively large energy gap. So when the number of neutrons and protons completely fill the energy levels of a given shell in the nucleus, the binding energy per nucleon will reach a local maximum and thus that particular configuration will have a longer lifetime than nearby isotopes that do not have filled shells. After one shell is filled, a new shell begins and if that isn't completly full, the element becomes less stable. A filled shell would have "magic numbers" of neutrons or protons and thus be stable. If a shell had both the right number of protons and neutrons neutrons, it would be "doubly magic". Because of the general trend of shorter half-lives with increasing atomic number, the elements that are "doubly magic" would appear to be like isolated, stable islands with longer half lifes surrounded by low stability elements when graphed such as in the picture below. It is through this that the hypothesis became known as the island of stability. It is unknown where the island of stability lies for sure, some models predict it is centred on atoms with 114 protons, while others put it near atoms with 120 or 126 protons. Oak Ridge Laboratories and the Joint Institute of Nuclear Research announced April 5, 2010, that they had developed a new synthesis of element 117 which has pushed the Periodic Table further into the neutron-rich setting for heaviest elements. New isotopes observed in these experiments continue a trend toward higher lifetimes for increased neutron numbers, providing evidence for the proposed "island of stability" for super-heavy nuclei.



=Decay of Transuranic Elements= media type="custom" key="6287233" width="200" height="200"

= = = = =Importance: Uses and Dangers= Transuranic elements have many uses. Some of them, such as plutonium, are used in nuclear power plants and in the thermal generators of space shuttles as well as in nuclear weapons because of its availability and properties. Americium is often used in smoke detectors and californium is used in radiation therapy to treat brain cancers. Others, such as neptunium, which has fewer uses in its normal state, can be irradiated with neutrons to produce plutonium. All transuranic elements pose hazards to the health and environment and are known to cause cancer and birth defects when exposed to people in long term or high quantities. There are many methods for storing radioactive transuranic elements. The most common method involves storing transuranic waste underwater for 3-5 years before moving them into barrels and storing them deep underground.

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