Scandium

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Scandium, symbol Sc, soft, silver-white metallic element with an atomic number of 21. Scandium is one of the transition elements in the periodic table.

Scandium was discovered in 1879 by the Swedish chemist Lars Fredrik Nilson, eight years after the Russian chemist Dmitry Ivanovich Mendeleyev had predicted, on the basis of the periodic law, that the element exists in nature and that its properties resemble those of the element boron. Scandium is sometimes regarded as one of the rare earth elements. Scandium occurs in rare minerals such as wolframite. It is 31st in order of abundance of the elements in the earth's crust. It forms trivalent, colorless salts.

Scandium melts at about 1541° C (about 2806° F), boils at about 2836° C (about 5137° F), and has a specific gravity of 3.0. The atomic weight of scandium is 44.956.

Wolframite

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Wolframite, opaque mineral composed of ferrous and manganous tungstate, and existing as an isomorphous mixture of the minerals ferberite and huebnerite. It crystallizes in the monoclinic system (see Crystal), exhibits perfect cleavage, and shines with a submetallic to resinous luster. The color ranges from brown to black; the hardness is 5 to 5.5, and the specific gravity is 7 to 7.5. Wolframite occurs in combination with such minerals as cassiterite, scheelite, quartz, pyrite, galena, sphalerite, and arsenopyrite, and is found mainly in China; Burma; New South Wales State, Australia; Bolivia; Germany; and Cornwall, England. In the U.S. principal deposits occur in Boulder County, Colorado; Nye County, Nevada; and the Black Hills, South Dakota. The principal use is as a source of tungsten, or wolfram.

Seaborgium

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Seaborgium, symbol Sg, chemical element with the atomic number 106. Seaborgium is produced artificially by nuclear fusion (in which an element with larger atoms is produced by fusing two smaller atoms from other elements). Each seaborgium atom contains a large nucleus, or central mass, containing positively charged particles called protons and neutral particles called neutrons. The large number of particles in the nucleus makes the atom unstable and causes the atom to split apart into smaller components soon after it is created. The International Union of Pure and Applied Chemistry named element 106 seaborgium (Sg) to honor Nobel Laureate Glenn T. Seaborg, who codiscovered plutonium and nine other transuranium elements. Seaborgium, which was previously called unnilhexium, is the first element that was named for a living person.

Seaborgium has the atomic number 106, which means that each Sg atom contains 106 protons in the nucleus. Scientists have created several isotopes of seaborgium, or forms of the element that contain different numbers of neutrons in the nucleus. For example, seaborgium-263 contains 106 protons and 157 neutrons (106 protons + 157 neutrons = atomic mass 263). Similarly, seaborgium-265 contains 106 protons and 159 neutrons.

Seaborgium belongs to Group 6 (VIb) on the periodic table, which also contains the naturally occurring (nonradioactive) elements chromium (Cr), molybdenum (Mo), and tungsten (W). Both chromium and molybdenum are important trace elements (elements that are vital for health but occur in the body in very small amounts) and are key components of certain proteins and enzymes. Because elements in the same group, or column, on the periodic table often share similar properties, scientists expected seaborgium to share properties with other Group 6 elements.