Chemical substances compound

In 1814, J.J. Berzelius succeeded for the first time in systematically naming chemical substances by building on the results of quantitative analyses and on the definition of the term "element by Lavoisier. In the 19th century, the number of known chemical compounds increased so rapidly that it became essential to classify them, to avoid a complete chaos of trivial names (see Section 2.2.4). 

Thus, if the user wants to look for literature including requested chemicals or reactions, it is possible to query the database by the first option Chemical Substance or Reaction , The compound can be entered as a query in three different ways drawing the chemical structure in a molecule editor (Chemical Structure) searching by names or identification number, such as the CAS Number (Structure Identifier) and searching by molecular formula (Figure 5-12). 

Heat stabilizers protect polymers from the chemical degrading effects of heat or uv irradiation. These additives include a wide variety of chemical substances, ranging from purely organic chemicals to metallic soaps to complex organometaUic compounds. By far the most common polymer requiring the use of heat stabilizers is poly(vinyl chloride) (PVC). However, copolymers of PVC, chlorinated poly(vinyl chloride) (CPVC), poly(vinyhdene chloride) (PVDC), and chlorinated polyethylene (CPE), also benefit from this technology. Without the use of heat stabilizers, PVC could not be the widely used polymer that it is, with worldwide production of nearly 16 million metric tons in 1991 alone (see Vinyl polymers). 

A significant advantage of the PLM is in the differentiation and recognition of various forms of the same chemical substance polymorphic forms, eg, brookite, mtile, and anatase, three forms of titanium dioxide calcite, aragonite and vaterite, all forms of calcium carbonate Eorms I, II, III, and IV of HMX (a high explosive), etc. This is an important appHcation because most elements and compounds possess different crystal forms with very different physical properties. PLM is the only instmment mandated by the U.S. Environmental Protection Agency (EPA) for the detection and identification of the six forms of asbestos (qv) and other fibers in bulk samples. 

J. H. Eletcher, O. C. Dermer, and R. B. Pox, Nomenclature of Organic Compounds, American Chemical Society Advances in Chemistry Series, Vol. 126, Washington, D.C., 1974 Selection of Index Namesfor Chemical Substances, Chem. Abstracts 82, Index Guide, American Chemical Society, Washington, D.C., 1982. 

V. A. Eilov, B. A. Ivin, and A. L. Bandman, eds.. Harmful Chemical Substances, Vol. 1, Elements in Group I-IH of the Periodic Table and Their Inorganic Compounds, Ellis Horwood, New York, 1993, pp. 344—350. 

The values given in the following table for the heats and free energies of formation of inorganic compounds are derived from a) Bichowsky and Rossini, Thermochemistry of the Chemical Substances, Reinhold, New York, 1936 (h) Latimer, Oxidation States of the Elements and Their Potentials in Aqueous Solution, Prentice-Hall, New York, 1938 (c) the tables of the American Petroleum Institute Research Project 44 at the National Bureau of Standards and (d) the tables of Selected Values of Chemical Thermodynamic Properties of the National Bureau of Standards. The reader is referred to the preceding books and tables for additional details as to methods of calculation, standard states, and so on. 

D-limonene (Florida Chemicals). A compound of optically active terpene (CioHie) derived as an extract from orange and lemon oils limited data shows veiy low viscosity at low temperatures—only one centipoise at —50°C natural substance having questionable stabihty, Theiminol D-12 (Mon.santo). A synthetic hydrocarbon clear liquid ... 

Chemicals are classed as either elements or compounds. The former are substances which cannot be split into simpler chemicals, e.g. copper. There are 90 naturally-occuiTing elements and 17 artificially produced. In nature the atoms of some elements can exist on their own, e.g. gold, whilst in others they link with other atoms of the same element to form molecules, e.g. two hydrogen atoms combine to form a molecule of hydrogen. Atoms of different elements can combine in simple numerical proportions 1 1, 1 2, 1 3, etc. to produce compounds, e.g. copper and oxygen combine to produce copper oxide hydrogen and oxygen combine to produce water. Compounds are therefore chemical substances which may be broken down to produce more than one element. Molecules are the smallest unit of a compound. 

Section 313 requires emissions reporting on the chemical categories listed below, in addition to the specific chemicals listed above. The metal compounds listed below, unless otherwise specified, are defined as including any unique chemical substance that contains the named metal (i.e., antimony, copper, etc.) as part of that chemical s structure. 

Antimony Compounds - Includes any unique chemical substance that contains antimony as part of that chemical s infrastructure. 

Online chemical dictionary with over 500,000 records on chemical substances found in the TOXLINH, TOXBACK65, TOXBACK74. RTECS, MEDLINE, and T1>B databa.scs, as well as the EPA TSCA Inventory. Search capability by synonynis, CAS Registry Numbers, and by classes of compounds. Prime lime connect cost is S54 per hour. 

Korper, m. body substance, compound Elec.) earth, ground. (Careful modern usage avoids the translation body for chemical substances.)... 

The quality of a drug substance is controlled by its specification. An internationally harmonized guideline on specifications and tests for chemical substances as active ingredients and in drug products makes reference to chiral compounds. This has recently been finalized and is discussed in Section 13.5.2. 

---