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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, Md, atomic number 101, the twelfth member of the actinide series of elements. Mendelevium does not occur in nature; it was discovered and is prepared by artificial nuclear transmutation of a lighter element. Known isotopes of mendelevium have mass numbers from 248 to 258 and half-lives from a few seconds to about 55 days. They are all produced by charged-particle bombardments of more abundant isotopes. The amounts of mendelevium which are produced and used for studies of chemical and nuclear properties are usually less than about a million atoms; this is of the order of a million times less than a weighable amount. Studies of the chemical properties of mendelevium have been limited to a tracer scale. The behavior of mendelevium in ion-exchange chromatography shows that it exists in aqueous solution primarily in the 3 + oxidation state characteristic of the actinide elements. However, it also has a dipositive (2+) and a monopositive (1+) oxidation state.
Industry:Science
A chemical element, Mo, atomic number 42, and atomic weight 95.94, in the periodic table in the triad of transition elements that includes chromium (atomic number 24) and tungsten (atomic number 74). Research has revealed it to be one of the most versatile chemical elements, finding applications not only in metallurgy but also in paints, pigments, and dyes; ceramics; electroplating; industrial catalysts; industrial lubricants; and organometallic chemistry. Molybdenum is an essential trace element in soils and in agricultural fertilizers. Molybdenum atoms have been found to perform key functions in enzymes (oxidases and reductases), with particular interest being directed toward its role in nitrogenase, which is employed by bacteria in legumes to convert inert nitrogen (N<sub>2</sub>) of the air into biologically useful ammonia (NH<sub>3</sub>).
Industry:Science
A chemical element, N, atomic number 7, atomic weight 14.0067. Nitrogen, a gas under normal conditions, is the lightest element of periodic group 5 (nitrogen family).
Industry:Science
A chemical element, Nb, atomic number 41 and atomic weight 92.906. In the United States this element was originally called columbium. The metallurgists and metals industry still use this older name.
Industry:Science
A chemical element, Ni, atomic number 28, a silver-white, ductile, malleable, tough metal. The atomic mass of naturally occurring nickel is 58.71.
Industry:Science
A chemical element, No, atomic number 102. Nobelium is a synthetic element produced in the laboratory. It decays by emitting an alpha particle, that is, a doubly charged helium ion. Only atomic quantities of the element have been produced to date. Nobelium is the tenth element heavier than uranium to be produced synthetically. It is the thirteenth member of the actinide series, a rare-earth-like series of elements.
Industry:Science
A chemical element, Os, atomic number 76, atomic weight 190.2. The element is a hard white metal of rare natural occurrence, usually found in nature alloyed with other platinum metals.
Industry:Science
A chemical element, P, atomic number 15, atomic weight 30.9738. Phosphorus forms the basis of a very large number of compounds, the most important class of which are the phosphates. For every form of life, phosphates play an essential role in all energy-transfer processes such as metabolism, photosynthesis, nerve function, and muscle action. The nucleic acids which among other things make up the hereditary material (the chromosomes) are phosphates, as are a number of coenzymes. Animal skeletons consist of a calcium phosphate.
Industry:Science
A chemical element, Pa, atomic number 91. Isotopes of mass numbers 216, 217, and 222–238 are known, all of them radioactive. Only <sup>231</sup>Pa, the parent of actinium, <sup>234</sup>Pa, and <sup>233</sup>Pa occur in nature. The most important of these is <sup>231</sup>Pa, an α-emitter with a half-life of 32,500 years. The artificial isotope, <sup>233</sup>Pa, is important as an intermediary in the production of fissile <sup>233</sup>U. Both <sup>231</sup>Pa and <sup>233</sup>Pa can be synthesized by neutron irradiation of thorium.
Industry:Science
A chemical element, Pb, atomic number 82 and atomic weight 207.19. Lead is a heavy metal (specific gravity 11.34 at 16°C or 61°F), of bluish color, which tarnishes to dull gray. It is pliable, inelastic, easily fusible, melts at 327.4°C (621.3°F), and boils at 1740°C (3164°F). The normal chemical valences are 2 and 4. It is relatively resistant to attack by sulfuric and hydrochloric acids but dissolves slowly in nitric acid. Lead is amphoteric, forming lead salts of acids as well as metal salts of plumbic acid. Lead forms many salts, oxides, and organometallic compounds.
Industry:Science
