| Themes > Science > Chemistry > Nuclear Chemistry > Transuranium Element > Transuranium Element |
Transuranium element, «TRANS yu RAY nee uhm,» is an element that is heavier than uranium, the heaviest element that occurs naturally on or in the earth. There are 23 known transuranium elements, which have atomic numbers (numbers of protons) from 93 to 118. All transuranium elements are radioactive, and many last only a fraction of a second. They are seldom found in nature because they rapidly change into other elements through a process called radioactive decay, also known as transmutation. Scientists produce transuranium elements using devices called particle accelerators. The scientists bombard a target nucleus with a beam of ions (electrically charged atoms) that have been boosted to tremendous speeds by the accelerator. Some of the nuclei collide, fuse, and form a new, heavier nucleus. Transuranium elements also occur in nuclear reactors and in the debris of nuclear explosions. Seventeen of the transuranium elements have official names. In order of their atomic numbers, they are neptunium (Np), plutonium (Pu), americium (Am), curium (Cm), berkelium (Bk), californium (Cf), einsteinium (Es), fermium (Fm), mendelevium (Md), nobelium (No), lawrencium (Lr), rutherfordium (Rf), dubnium (Db), seaborgium (Sg), bohrium (Bh), hassium (Hs), and meitnerium (Mt). The International Union of Pure and Applied Chemistry (IUPAC) is the recognized authority in crediting the discovery of elements and assigning names to them. A dispute arose concerning the naming of the elements with atomic numbers 104 through 109, which had been discovered from 1969 to 1984. Until 1997, when the scientific community approved the names, they were referred to by their atomic numbers as elements 104, 105, 106, 107, 108, and 109. In 1994, an international team of scientists at the Heavy Ion Research Center in Darmstadt, Germany, announced the creation of elements 110 and 111. In 1996, the Darmstadt team announced the production of element 112. In 1999, Russian and American physicists working at the Joint Institute for Nuclear Research in Dubna, near Moscow, announced that they had created element 114 in experiments ending in December 1998. Also in 1999, researchers at Lawrence Berkeley National Laboratory in California announced that they had produced elements 116 and 118. The Berkeley group created element 118 in an accelerator, and that element decayed into element 116. By mid-1999, IUPAC had not evaluated the claims for the production of elements 110, 111, 112, 114, 116, or 118, nor had IUPAC named the elements. |
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