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McGraw Hill Financial, Inc. is an American publicly traded corporation headquartered in Rockefeller Center in New York City. Its primary areas of business are financial, publishing, and business services.
A chemical element, symbol Rh, atomic number 45, relative atomic weight 102.905. Rhodium is a transition metal and one of the group of platinum metals (ruthenium, osmium, rhodium, iridium, palladium, and platinum) that share similar chemical and physical properties. The gas-phase atom has the electronic configuration 1<i>s</i><sup>2</sup>, 2<i>s</i><sup>2</sup>, 2<i>p</i><sup>6</sup>, 3<i>s</i><sup>2</sup>, 3<i>p</i><sup>6</sup>, 3<i>d</i><sup>10</sup>, 4<i>s</i><sup>2</sup>, 4<i>p</i><sup>6</sup>, 4<i>d</i><sup>8</sup>, 5<i>s</i><sup>1</sup>. The ionic radius for the cation Rh<sup>3+</sup> is 0.0665 nanometer, and the metallic radius is 0.1345 nm.
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A chemical element, symbol Rn, atomic number 86. Radon is produced as a gaseous emanation from the radioactive decay of radium. The element is highly radioactive and decays by the emission of energetic alpha particles. Radon is the heaviest of the noble, or inert, gas group and thus is characterized by chemical inertness. All isotopes are radioactive with short half-lives.
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A chemical element, symbol Ru, atomic number 44. The element is a brittle gray-white metal of low natural abundance, usually found alloyed with other platinum metals in nature. The discovery of the element ruthenium was established in 1844 by K. K. Klaus; it was the last of the platinum metals to be identified as an element.
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A chemical element, symbol Sc, atomic number 21, atomic weight 44.9559. The only naturally occurring isotope is <sup>45</sup>Sc. The electronic configuration of the ground-state, gaseous atom consists of the argon rare-gas core plus three more electrons in the 3<i>d</i><sup>1</sup>4<i>s</i><sup>2</sup> levels. It is the first element in the periodic table to have an unfilled inner shell and thus is the first transition metal. It is one of the elements of the rare-earth group as defined by the International Union of Pure and Applied Chemistry.
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A chemical element, symbol Se, atomic number 34, atomic weight 78.96, first isolated by J. J. Berzelius in 1817 from sulfur used in the Swedish sulfuric acid industry. The properties of this element are similar to those of tellurium.
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A chemical element, symbol Sg, atomic number 106. Seaborgium has chemical properties similar to tungsten. It was synthesized and identified in 1974. This is the fourteenth of the synthetic transuranium elements, the laboratory-made elements heavier than uranium. Uranium is the heaviest commonly occurring element in nature (traces of plutonium, atomic number 94, have been detected in nature), having the atomic number 92. The lightest transuranium element, neptunium, with atomic number 93, was synthesized first in 1940, and the heaviest previous transuranium element, dubnium with atomic number 105, was synthesized in 1970.
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A chemical element, symbol Si, atomic number 14, and atomic weight 28.086. Silicon is the most abundant electropositive element in the Earth's crust. The element is a metalloid with a decided metallic luster; it is quite brittle. It crystallizes in the diamond lattice, has a specific gravity of 2.42 at 20°C (68°F), melts at 1420°C (2590°F), and boils at 3280°C (5940°F). The element is usually tetravalent in its compounds, although sometimes divalent, and is decidedly electropositive in its chemical behavior. In addition, pentacoordinate and hexacoordinate compounds of silicon are known.
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A chemical element, symbol Sm, atomic number 62, belonging to the rare-earth group. Its atomic weight is 150.35, and the naturally occurring isotopes are <sup>144</sup>Sm (3.09%), <sup>147</sup>Sm (14.97%), <sup>148</sup>Sm 11.24%, <sup>149</sup>Sm 13.83%, <sup>150</sup>Sm 7.44%, <sup>152</sup>Sm 26.72%, and <sup>154</sup>Sm 22.71%. <sup>147</sup>Sm, <sup>148</sup>Sm, and <sup>149</sup>Sm are radioactive and emit alpha particles. The half-lives are 1.06 × 10<sup>11</sup> years, 1.2 × 10<sup>13</sup> years, and 4 × 10<sup>14</sup> years, respectively.
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A chemical element, symbol Sn, atomic number 50, atomic weight 118.69. Tin forms tin(II) or stannous (Sn<sup>2+</sup>), and tin(IV) or stannic (Sn<sup>4+</sup>) compounds, as well as complex salts of the stannite (M<sub>2</sub>SnX<sub>4</sub>) and stannate (M<sub>2</sub>SnX<sub>6</sub>) types.
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A chemical element, symbol Ta, atomic number 73, and atomic weight 180.948. It is a member of the vanadium group of the periodic table and is in the 5<i>d</i> transitional series. Oxidation states of IV, III, and II are also known.
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