Chemical substances number

RTECS Registry of Toxic Effects of Chemical Substances number is a unique and unchanging number used to cross-reference the RTECS database, which is a compendium of data extracted from the open scientific literature. Six types of toxicity data are included in each file (1) primary irritation, (2) mutagenic effects, (3) reproductive effects, (4) tumorigenic effects, (5) acute toxicity, and (6) other multiple dose toxicity. 

RTECS number Registry of Toxic Effects of Chemical Substances number is published by NIOSH and present basic toxicity data on thousands of materials. 

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). 

The number and kind of defects in a given specimen, as well as the crystal habit and with it the proportion of different crystal faces exposed, will in general depend in considerable degree on the details of preparation. The production of a standard sample of a given chemical substance, having reproducible adsorptive behaviour, remains therefore as much an art as a science. 

Fine chemicals are produced by a wide spectmm of manufacturers, largely because the distinction between different kinds of chemicals is not sharp. There are specialty producers of fine chemicals. Many companies that manufacture dmgs also manufacture the chemical substances that are used in preparing the dosage forms. A number of companies manufacture dmg chemicals and food chemicals. Some fine chemicals are made by manufacturers of heavy chemicals, and either may be simply a segment of their regular production, or some of that production which has been subjected to additional purification steps. Many fine chemicals are imported into the United States from countries such as Japan, Germany, and the Netherlands. 

Registry File. This CAS file contains more than 11.8 million chemical substance records. About 8,000—14,000 records are added each week as new substances are identified by the CAS Registry System. The substance records contain CAS Registry Numbers, chemical names, stmctures, molecular formulas, ring data biosequence information, and classes for polymers. AH of this information may be displayed. 

A number of methods have been developed to introduce context to on-line databases, enabling searches to be refined to minimized false retrieval. One of the earliest techniques is proximity searching, in which two words are required to be adjacent, or within a limited distance from each other in text. The assignment of roles to chemical substances is a method of precoordinating concepts. A substance can be identified as a reactant, as a product, and in some systems in a number of additional roles. For example, by searching for documents in which formaldehyde is a product, documents in which it is a reactant, or in which it undergoes no reaction, are thus eliminated. 

Toxic Substances Control Act. EPA regulates the manufacture, use, and exposure to ha2ardous or toxic chemicals under a number of laws. Eor the chemical industry, the law of prime concern is the Toxic Substance Control Act (TSCA) (10), which was passed by the U.S. Congress in 1976. The two main goals of TSCA are acquisition of sufficient information to identify and evaluate potential ha2ards from chemical substances, and regulation of the production, use, distribution, and disposal of these substances. 

Vinyl chloride is Hsted as "ethene, chloro-" on the Toxic Substances Control Act (TSCA) inventory and on the Canadian Domestic Substances List (DSL). It is Hsted as "chloroethylene" on the European Inventory of Existing Commercial Chemical Substances (EINECS), bearing the identification number 2008 310 (149). 

The phase rule is a mathematical expression that describes the behavior of chemical systems in equilibrium. A chemical system is any combination of chemical substances. The substances exist as gas, liquid, or solid phases. The phase rule applies only to systems, called heterogeneous systems, in which two or more distinct phases are in equilibrium. A system cannot contain more than one gas phase, but can contain any number of liquid and solid phases. An alloy of copper and nickel, for example, contains two solid phases. The rule makes possible the simple correlation of very large quantities of physical data and limited prediction of the behavior of chemical systems. It is used particularly in alloy preparation, in chemical engineering, and in geology. 

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. 

CRS provides information on chemical substances and how they are represented in the Environmental Protection Agency regulations and data systems. A search engine for chemicals by CAS number, name, molecular formula, chemical type, definition, or other data identifiers. 

Since 1965, CA has assigned a Registry Number to each unique chemical substance. This is a number of the form [766-51-8] that remains invariant, no matter what names are used in the literature. More than 10 million numbers have already been assigned and thousands are added each week. Registry Numbers are primarily for computer use. All numbers so far have been pubUshed with the CA preferred names in a multivolume Registry Handbook . 

A chemical compound is a substance that contains more than one element. The relative amounts of the elements in a particular compound do not change Every molecule of a particular chemical substance contains a characteristic number of atoms of its constituent elements. For example, every water molecule contains two... 

Early experiments showed that strong electrical forces can strip electrons from atoms. Atoms can also gain electrons under the influence of electrical force. In fact, much of the chemistry that takes place in the world around us involves electrons shifting from one chemical substance to another. Chemical reactions have no effect, however, on the stmctures of nuclei. All atoms of a particular element have the same number of protons in the nucleus, and these do not change during chemical processes. The defining feature of an element, therefore, is the charge carried by the protons in its nucleus. 

In the early days of chemistry, the list of known compounds was short, so chemists could memorize the names of all of them. New compounds were often named for their place of origin, physical appearance, or properties. As the science of chemistry grew, the number of known compounds increased quickly. Soon, nobody could keep track of all of the common names. Today, more than 20 million compounds are known, and thousands of new ones are discovered or created each year. Consequently, chemists need systematic procedures for naming chemical compounds. The International Union of Pure and Applied Chemistry (lUPAC) has established uniform guidelines for naming various types of chemical substances, and chemists increasingly use lUPAC-approved names rather than their common counterparts. Systematic names are less colorful than common names, but they make chemistry less hectic because it is much easier to learn a few systematic guidelines than to memorize the names of thousands of individual compounds. 

The ionic model describes a number of metal halides, oxides, and sulfides, but it does not describe most other chemical substances adequately. Whereas substances such as CaO, NaCl, and M 2 behave like simple cations and anions held together by electrical attraction, substances such as CO, CI2, and HE do not. In a crystal of Mgp2, electrons have been transferred from magnesium atoms to fluorine atoms, but the stability of HE molecules arises from the sharing of electrons between hydrogen atoms and fluorine atoms. We describe electron sharing, which is central to molecular stability, in Chapters 9 and 10. 

Although there is no universal consensus as to the scale of production and use of chemical substances, it is estimated that the average annual world production of such substances is in excess of 450 million tonnes. Other estimates indicate that there are currently identified over five million distinct chemical compounds, with this number increasing at the rate of over a third of a million per year. Whilst many of these compounds are clearly not in everyday commercial or industrial use, it is estimated that at least 100,000 chemical substances can be considered to be in everyday use on a substantial scale, and that this number is being added to at the rate of at least several hundred per year, in the case of substances which are produced in quantities in excess of one tonne per year. 

Professor Martel s book addresses specifically some of the more technical eispects of the risk assessment process, mainly in the areas of hazard identification, and of the consequence/effect analysis elements, of the overall analysis whilst where appropriate setting these aspects in the wider context. The book brings together a substantial corpus of information, drawn from a number of sources, about the toxic, flammable and explosive properties and effect (ie harm) characteristics of a wide range of chemical substances likely to be found in industry eind in the laboratory, and also addresses a spectrum of dangerous reactions of, or between, such substances which may be encountered. This approach follows the classical methodology and procedures of hazard identification, analysing material properties eind... 

A detonator, in the form of explosive plates made with tetryl then a screen made of cellulose acetate plates is placed in a wooden container. A 26 mm diameter cylinder full of the substance to be analysed is placed on the screen, and finally a steel plate on top of the cylinder is added. If the substance transmits the detonation, the steel plate will be pierced and not projected. Piercing serves as an indicator of detonation transmission. The number of cellulose acetate disks needed between the sample and the detonator to prevent the detonation from being transmitted is found. Only one is needed for most chemical substances, but with m-dinitrobenzene, 240 are required. 

When transporting dangerous chemical substances the carrier has to affix at the rear of the vehicle and/or substance packaging plates and labels, a danger label and/or a substance number.The risk number contains at least two figures the first being the main risk, the second the secondary risk. 0 indicates the absence of a secondary risk. If the main risk number is divided into two, this indicates an aggravated risk. The numbers that are of interest here are ... 

Apart from the two classifications described above, electrolytes may also be classified according to the number and valence of the ions produced. Thus, sodium chloride and copper sulfate may both be termed binary electrolytes since one molecule of each of these chemical substances is capable of producing two ions. In the case of sodium chloride, both the ions produced are univalent so that this substance may also be called a uni-univalent electrolyte. Copper sulfate, however, yields two bivalent ions and so may be called a bibivalent electrolyte. The valences of the ions are quoted in the positive-negative sequence. Calcium chloride and potassium sulfate are both ternary electrolytes since one molecule of each yields three ions the former is bi-univalent, whilst the latter is uni-bivalent. 

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