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The element is dimorphic, existing as a yellow, metastable form composed of Sb4 molecules, as in antimony vapor and the structural unit in yellow antimony; and a gray, metallic form, which crystallizes with a layered rhombohedral structure. Antimony…

A substance that, when present at a lower concentration than that of the oxidizable substrate, significantly inhibits or delays oxidative processes, while being itself oxidized. For antioxidants, such as ascorbic acid (Fig. 1), antioxidative…

All measures required to combat enemy submarines, including strategy, operational employment of forces, tactics, and a wide variety of equipment and weapons to find and destroy submarines and to neutralize their weapons. Goals The key physical facts…

A mixture of one part by volume of concentrated nitric acid and three parts of concentrated hydrochloric acid. Aqua regia was so named by the alchemists because of its ability to dissolve platinum and gold. Either acid alone will not dissolve these…

The weapons, equipment, and supplies that permit lethal or nonlethal devices to strike their targets. Armaments can be classified as field artillery, individual and crew-served weapons (infantry), armor and antiarmor, antiaircraft, helicopter…

A hydrocarbon with a chemistry similar to that of benzene. Aromatic hydrocarbons are either benzenoid or nonbenzenoid. Benzenoid aromatic hydrocarbons contain one or more benzene rings and are by far the more common and the more important…

The application of chemistry to the technical examination, authentication, and preservation of cultural property. Chemists working in museums engage in a broad range of investigations, most frequently studying the chemical composition and structure…

A chemical element, At, atomic number 85. Astatine is the heaviest of the halogen groups, filling the place immediately below iodine in group 17 of the periodic table. Astatine is a highly unstable element existing only in short-lived radioactive…

A chemical reaction or series of reactions leading to the predominant or exclusive formation of a single enantiomer, that is, one of an isomeric pair of chemical compounds whose molecules are nonsuperimposable mirror images. Enantiomers are said to…

The maximum incorporation of the starting materials into the final product for any chemical reaction.A broad imperative for synthetic chemists today is the need to develop innovative and sophisticated synthetic methods to keep pace with the…