42-471: Dinitrotoluenes could refer to one of the following compounds: 2,3-Dinitrotoluene 2,4-Dinitrotoluene 2,5-Dinitrotoluene 2,6-Dinitrotoluene 3,4-Dinitrotoluene 3,5-Dinitrotoluene [REDACTED] Index of chemical compounds with the same name This set index article lists chemical compounds articles associated with the same name. If an internal link led you here, you may wish to change
84-424: A chemical compound ; the concept is most readily understood when considering pure chemical substances . It follows from their being composed of fixed proportions of two or more types of atoms that chemical compounds can be converted, via chemical reaction , into compounds or substances each having fewer atoms. A chemical formula is a way of expressing information about the proportions of atoms that constitute
126-419: A solid-state reaction , or the electron transfer reaction of reactive metals with reactive non-metals, such as halogen gases. Ionic compounds typically have high melting and boiling points , and are hard and brittle . As solids they are almost always electrically insulating , but when melted or dissolved they become highly conductive , because the ions are mobilized. An intermetallic compound
168-622: A compound. A compound can be transformed into a different substance by a chemical reaction , which may involve interactions with other substances. In this process, bonds between atoms may be broken and/or new bonds formed. There are four major types of compounds, distinguished by how the constituent atoms are bonded together. Molecular compounds are held together by covalent bonds ; ionic compounds are held together by ionic bonds ; intermetallic compounds are held together by metallic bonds ; coordination complexes are held together by coordinate covalent bonds . Non-stoichiometric compounds form
210-412: A continuous three-dimensional network, usually in a crystalline structure . Ionic compounds containing basic ions hydroxide (OH ) or oxide (O ) are classified as bases. Ionic compounds without these ions are also known as salts and can be formed by acid–base reactions . Ionic compounds can also be produced from their constituent ions by evaporation of their solvent , precipitation , freezing ,
252-510: A different chemical composition by interaction with a second chemical compound via a chemical reaction . In this process, bonds between atoms are broken in both of the interacting compounds, and then bonds are reformed so that new associations are made between atoms. Schematically, this reaction could be described as AB + CD → AD + CB , where A, B, C, and D are each unique atoms; and AB, AD, CD, and CB are each unique compounds. Chemical Abstracts Service Chemical Abstracts Service ( CAS )
294-516: A disputed marginal case. A chemical formula specifies the number of atoms of each element in a compound molecule, using the standard chemical symbols with numerical subscripts . Many chemical compounds have a unique CAS number identifier assigned by the Chemical Abstracts Service . Globally, more than 350,000 chemical compounds (including mixtures of chemicals) have been registered for production and use. The term "compound"—with
336-444: A meaning similar to the modern—has been used at least since 1661 when Robert Boyle's The Sceptical Chymist was published. In this book, Boyle variously used the terms "compound", "compounded body", "perfectly mixt body", and "concrete". "Perfectly mixt bodies" included for example gold, lead, mercury, and wine. While the distinction between compound and mixture is not so clear, the distinction between element and compound
378-522: A new headquarters north of campus. Ground was broken in 1971 for an expansion to the building designed by architects Brubaker/Brandt to accommodate the review of 400,000 new research reports printed each year. The 5-story 142,000 square foot building opened in May 1973. In 2007, the ACS designated its Chemical Abstracts Service subdivision an ACS National Historic Chemical Landmark in recognition of its significance as
420-566: A particular chemical compound, using chemical symbols for the chemical elements, and subscripts to indicate the number of atoms involved. For example, water is composed of two hydrogen atoms bonded to one oxygen atom: the chemical formula is H 2 O. In the case of non-stoichiometric compounds , the proportions may be reproducible with regard to their preparation, and give fixed proportions of their component elements, but proportions that are not integral [e.g., for palladium hydride , PdH x (0.02 < x < 0.58)]. Chemical compounds have
462-496: A positively charged cation . The nonmetal will gain the electrons from the metal, making the nonmetal a negatively charged anion . As outlined, ionic bonds occur between an electron donor, usually a metal, and an electron acceptor, which tends to be a nonmetal. Hydrogen bonding occurs when a hydrogen atom bonded to an electronegative atom forms an electrostatic connection with another electronegative atom through interacting dipoles or charges. A compound can be converted to
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#1732858346990504-475: A selected journal. Also included is its language of text and language of summaries. The range is from 1907 to the present, including both serial and non-serial scientific and technical publications. The database is updated quarterly. Beyond CASSI lists abbreviated journal titles from early chemical literature and other historical reference sources. Chemical Abstracts ( CA ) began as a volunteer effort and developed from there. The use of volunteer abstractors
546-447: A solid state dependent on how low the temperature of the environment is. A covalent bond , also known as a molecular bond, involves the sharing of electrons between two atoms. Primarily, this type of bond occurs between elements that fall close to each other on the periodic table of elements , yet it is observed between some metals and nonmetals. This is due to the mechanism of this type of bond. Elements that fall close to each other on
588-469: A unique and defined chemical structure held together in a defined spatial arrangement by chemical bonds . Chemical compounds can be molecular compounds held together by covalent bonds , salts held together by ionic bonds , intermetallic compounds held together by metallic bonds , or the subset of chemical complexes that are held together by coordinate covalent bonds . Pure chemical elements are generally not considered chemical compounds, failing
630-445: Is a central theme. Quicksilver ... with Aqua fortis will be brought into a ... white Powder ... with Sulphur it will compose a blood-red and volatile Cinaber. And yet out of all these exotick Compounds, we may recover the very same running Mercury. Boyle used the concept of "corpuscles"—or "atomes", as he also called them—to explain how a limited number of elements could combine into a vast number of compounds: If we assigne to
672-469: Is a database of chemical and bibliographic information. Originally it was available only as a client application (for both Windows and MacOS operating systems), a web version was released in 2008. By that time it had a graphical interface, and was able to do graphical searches for chemical structures and reactions (the first database to allow such functions), as well as keyword searches for literature in chemistry and related disciplines. SciFinder Scholar
714-864: Is a division of the American Chemical Society . It is a source of chemical information and is located in Columbus, Ohio , United States . Chemical Abstracts is a periodical index that provides numerous tools such as SciFinder as well as tagged keywords, summaries, indexes of disclosures, and structures of compounds in recently published scientific documents. Approximately 8,000 journals , technical reports , dissertations , conference proceedings , and new books , available in at least 50 different languages, are monitored yearly, as are patent specifications from 27 countries and two international organizations. Chemical Abstracts ceased print publication on January 1, 2010. The two principal databases that support
756-403: Is a type of metallic alloy that forms an ordered solid-state compound between two or more metallic elements. Intermetallics are generally hard and brittle, with good high-temperature mechanical properties. They can be classified as stoichiometric or nonstoichiometric intermetallic compounds. A coordination complex consists of a central atom or ion, which is usually metallic and is called
798-405: Is different from Wikidata All set index articles Commons category link is on Wikidata Chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities ) containing atoms from more than one chemical element held together by chemical bonds . A molecule consisting of atoms of only one element is therefore not
840-408: Is needed in order to fully take advantage of SciFinder capabilities. CASSI stands for Chemical Abstracts Service Source Index . Since 2009, this formerly print and CD-ROM compilation is available as a free online resource to look up and confirm publication information. The online CASSI Search Tool provides titles and abbreviations, CODEN , ISSN , publisher , and date of first issue (history) for
882-493: Is neutral overall, but consists of positively charged ions called cations and negatively charged ions called anions . These can be simple ions such as the sodium (Na ) and chloride (Cl ) in sodium chloride , or polyatomic species such as the ammonium ( NH 4 ) and carbonate ( CO 3 ) ions in ammonium carbonate . Individual ions within an ionic compound usually have multiple nearest neighbours, so are not considered to be part of molecules, but instead part of
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#1732858346990924-529: The National Institutes of Health . The chemical information is produced by CAS, and is prepared by the CAS Registry System, which identifies each compound with a specific CAS registry number , index name, and graphic representation of its chemical structure. The assignment of chemical names is done according to the chemical nomenclature rules for CA index names, which is slightly different from
966-452: The coordination centre , and a surrounding array of bound molecules or ions, that are in turn known as ligands or complexing agents. Many metal-containing compounds, especially those of transition metals , are coordination complexes. A coordination complex whose centre is a metal atom is called a metal complex of d block element. Compounds are held together through a variety of different types of bonding and forces. The differences in
1008-449: The oxygen molecule (O 2 ); or it may be heteronuclear , a chemical compound composed of more than one element, as with water (two hydrogen atoms and one oxygen atom; H 2 O). A molecule is the smallest unit of a substance that still carries all the physical and chemical properties of that substance. An ionic compound is a chemical compound composed of ions held together by electrostatic forces termed ionic bonding . The compound
1050-896: The Corpuscles, whereof each Element consists, a peculiar size and shape ... such ... Corpuscles may be mingled in such various Proportions, and ... connected so many ... wayes, that an almost incredible number of ... Concretes may be compos’d of them. In his Logick , published in 1724, the English minister and logician Isaac Watts gave an early definition of chemical element, and contrasted element with chemical compound in clear, modern terms. Among Substances, some are called Simple, some are Compound ... Simple Substances ... are usually called Elements, of which all other Bodies are compounded: Elements are such Substances as cannot be resolved, or reduced, into two or more Substances of different Kinds. ... Followers of Aristotle made Fire, Air, Earth and Water to be
1092-459: The Earth. Other compounds regarded as chemically identical may have varying amounts of heavy or light isotopes of the constituent elements, which changes the ratio of elements by mass slightly. A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. A molecule may be homonuclear , that is, it consists of atoms of one chemical element, as with two atoms in
1134-524: The Truth ;; tho' they are not all agreed ... Compound Substances are made up of two or more simple Substances ... So a Needle is simple Body, being made only of Steel; but a Sword or a Knife is a compound because its ... Handle is made of Materials different from the Blade. Any substance consisting of two or more different types of atoms ( chemical elements ) in a fixed stoichiometric proportion can be termed
1176-565: The different products are CAplus and Registry. CAS References consists of bibliographic information and abstracts for all articles in chemical journals worldwide, and chemistry-related articles from all scientific journals, patents, and other scientific publications. As of 2023 , the CAS Registry contains information on more than 200 million organic and inorganic substances, and about 70 million protein and nucleic acid sequences . The sequence information comes from CAS and GenBank , produced by
1218-400: The fixed ratios. Many solid chemical substances—for example many silicate minerals —are chemical substances, but do not have simple formulae reflecting chemically bonding of elements to one another in fixed ratios; even so, these crystalline substances are often called " non-stoichiometric compounds ". It may be argued that they are related to, rather than being chemical compounds, insofar as
1260-508: The four Elements, of which all earthly Things were compounded; and they suppos'd the Heavens to be a Quintessence, or fifth sort of Body, distinct from all these : But, since experimental Philosophy ... have been better understood, this Doctrine has been abundantly refuted. The Chymists make Spirit, Salt, Sulphur, Water and Earth to be their five Elements, because they can reduce all terrestrial Things to these five : This seems to come nearer
1302-490: The internationally standard IUPAC names , according to the rules of IUPAC . CAS databases are available via two principal database systems, STN, and SciFinder. STN (Scientific & Technical Information Network) International is operated jointly by CAS and FIZ Karlsruhe , and is intended primarily for information professionals, using a command language interface. In addition to CAS databases, STN also provides access to many other databases, similar to Dialog . SciFinder
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1344-452: The link to point directly to the intended article. External links [ edit ] [REDACTED] Media related to Dinitrotoluenes at Wikimedia Commons Retrieved from " https://en.wikipedia.org/w/index.php?title=Dinitrotoluene&oldid=1119984456 " Categories : Set index articles on chemistry Explosive chemicals Nitrotoluenes Hidden categories: Articles with short description Short description
1386-536: The periodic table tend to have similar electronegativities , which means they have a similar affinity for electrons. Since neither element has a stronger affinity to donate or gain electrons, it causes the elements to share electrons so both elements have a more stable octet . Ionic bonding occurs when valence electrons are completely transferred between elements. Opposite to covalent bonding, this chemical bond creates two oppositely charged ions. The metals in ionic bonding usually lose their valence electrons, becoming
1428-494: The two or more atom requirement, though they often consist of molecules composed of multiple atoms (such as in the diatomic molecule H 2 , or the polyatomic molecule S 8 , etc.). Many chemical compounds have a unique numerical identifier assigned by the Chemical Abstracts Service (CAS): its CAS number . There is varying and sometimes inconsistent nomenclature differentiating substances, which include truly non-stoichiometric examples, from chemical compounds, which require
1470-455: The types of bonds in compounds differ based on the types of elements present in the compound. London dispersion forces are the weakest force of all intermolecular forces . They are temporary attractive forces that form when the electrons in two adjacent atoms are positioned so that they create a temporary dipole . Additionally, London dispersion forces are responsible for condensing non polar substances to liquids, and to further freeze to
1512-421: The variability in their compositions is often due to either the presence of foreign elements trapped within the crystal structure of an otherwise known true chemical compound , or due to perturbations in structure relative to the known compound that arise because of an excess of deficit of the constituent elements at places in its structure; such non-stoichiometric substances form most of the crust and mantle of
1554-559: The west bank of the Olentangy River , just north of The Ohio State campus. This campus became well known in the Columbus area and famous as the site of many Columbus Symphony Orchestra pop concerts. In 2009, the campus consisted of three buildings. In 1907, William A. Noyes had enlarged the Review of American Chemical Research , an abstracting publication begun by Arthur Noyes in 1895 that
1596-477: Was a key factor in its long-term success. Dale B. Baker became the CAS Director upon Crane's retirement in 1958. According to CAS, his visionary view of CAS' potential "led to expansion, modernization, and the forging of international alliances with other information organizations." CAS was an early leader in the use of computer technology to organize and disseminate information. The CAS Chemical Registry System
1638-551: Was a very similar a product developed for academic institutions, but discontinued in 2023. In 2017 the ACS released SciFinder-n as a web-only product with the same data content and improved user interface and search functions. SciFinder is considered as the best source of chemical information worldwide, with substantially larger number of relevant information sources than Web of Science or Scopus with Reaxys . However, due to its unique and unusual search functions, substantial training
1680-401: Was introduced in 1965. CAS developed a unique registry number to identify chemical substances. Agencies such as the U.S. Environmental Protection Agency and local fire departments around the world now rely on these numbers for the definite identification of substances. According to the ACS, this is the largest chemical substance database in the world. In 1965, CAS left their offices at OSU for
1722-474: Was phased out in 1994. Chemical Abstracts has been associated with the American Chemical Society in one way or another since 1907. For many years, beginning in 1909, the offices of Chemical Abstracts were housed in various places on the Columbus, Ohio campus of Ohio State University , including McPherson Laboratory and Watts Hall . In 1965, CAS moved to a new 50-acre (200,000 m ) site on
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1764-401: Was the forerunner of Chemical Abstracts . When it became evident that a separate publication containing these abstracts was needed, Noyes became the first editor of the new publication, Chemical Abstracts . E. J. Crane became the first Director of Chemical Abstracts Service when it became an American Chemical Society division in 1956. Crane had been CA editor since 1915, and his dedication
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