1.
Jmol
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Jmol is computer software for molecular modelling chemical structures in 3-dimensions. Jmol returns a 3D representation of a molecule that may be used as a teaching tool and it is written in the programming language Java, so it can run on the operating systems Windows, macOS, Linux, and Unix, if Java is installed. It is free and open-source software released under a GNU Lesser General Public License version 2.0, a standalone application and a software development kit exist that can be integrated into other Java applications, such as Bioclipse and Taverna. A popular feature is an applet that can be integrated into web pages to display molecules in a variety of ways, for example, molecules can be displayed as ball-and-stick models, space-filling models, ribbon diagrams, etc. Jmol supports a range of chemical file formats, including Protein Data Bank, Crystallographic Information File, MDL Molfile. There is also a JavaScript-only version, JSmol, that can be used on computers with no Java, the Jmol applet, among other abilities, offers an alternative to the Chime plug-in, which is no longer under active development. While Jmol has many features that Chime lacks, it does not claim to reproduce all Chime functions, most notably, Chime requires plug-in installation and Internet Explorer 6.0 or Firefox 2.0 on Microsoft Windows, or Netscape Communicator 4.8 on Mac OS9. Jmol requires Java installation and operates on a variety of platforms. For example, Jmol is fully functional in Mozilla Firefox, Internet Explorer, Opera, Google Chrome, fast and Scriptable Molecular Graphics in Web Browsers without Java3D
2.
ChemSpider
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ChemSpider is a database of chemicals. ChemSpider is owned by the Royal Society of Chemistry, the database contains information on more than 50 million molecules from over 500 data sources including, Each chemical is given a unique identifier, which forms part of a corresponding URL. This is an approach to develop an online chemistry database. The search can be used to widen or restrict already found results, structure searching on mobile devices can be done using free apps for iOS and for the Android. The ChemSpider database has been used in combination with text mining as the basis of document markup. The result is a system between chemistry documents and information look-up via ChemSpider into over 150 data sources. ChemSpider was acquired by the Royal Society of Chemistry in May,2009, prior to the acquisition by RSC, ChemSpider was controlled by a private corporation, ChemZoo Inc. The system was first launched in March 2007 in a release form. ChemSpider has expanded the generic support of a database to include support of the Wikipedia chemical structure collection via their WiChempedia implementation. A number of services are available online. SyntheticPages is an interactive database of synthetic chemistry procedures operated by the Royal Society of Chemistry. Users submit synthetic procedures which they have conducted themselves for publication on the site and these procedures may be original works, but they are more often based on literature reactions. Citations to the published procedure are made where appropriate. They are checked by an editor before posting. The pages do not undergo formal peer-review like a journal article. The comments are moderated by scientific editors. The intention is to collect practical experience of how to conduct useful chemical synthesis in the lab, while experimental methods published in an ordinary academic journal are listed formally and concisely, the procedures in ChemSpider SyntheticPages are given with more practical detail. Comments by submitters are included as well, other publications with comparable amounts of detail include Organic Syntheses and Inorganic Syntheses
3.
PubChem
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PubChem is a database of chemical molecules and their activities against biological assays. The system is maintained by the National Center for Biotechnology Information, a component of the National Library of Medicine, PubChem can be accessed for free through a web user interface. Millions of compound structures and descriptive datasets can be downloaded via FTP. PubChem contains substance descriptions and small molecules with fewer than 1000 atoms and 1000 bonds, more than 80 database vendors contribute to the growing PubChem database. PubChem consists of three dynamically growing primary databases, as of 28 January 2016, Compounds,82.6 million entries, contains pure and characterized chemical compounds. Substances,198 million entries, contains also mixtures, extracts, complexes, bioAssay, bioactivity results from 1.1 million high-throughput screening programs with several million values. PubChem contains its own online molecule editor with SMILES/SMARTS and InChI support that allows the import and export of all common chemical file formats to search for structures and fragments. In the text search form the database fields can be searched by adding the name in square brackets to the search term. A numeric range is represented by two separated by a colon. The search terms and field names are case-insensitive, parentheses and the logical operators AND, OR, and NOT can be used. AND is assumed if no operator is used, example,0,5000,50,10 -5,5 PubChem was released in 2004. The American Chemical Society has raised concerns about the publicly supported PubChem database and they have a strong interest in the issue since the Chemical Abstracts Service generates a large percentage of the societys revenue. To advocate their position against the PubChem database, ACS has actively lobbied the US Congress, soon after PubChems creation, the American Chemical Society lobbied U. S. Congress to restrict the operation of PubChem, which they asserted competes with their Chemical Abstracts Service
4.
International Chemical Identifier
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Initially developed by IUPAC and NIST from 2000 to 2005, the format and algorithms are non-proprietary. The continuing development of the standard has supported since 2010 by the not-for-profit InChI Trust. The current version is 1.04 and was released in September 2011, prior to 1.04, the software was freely available under the open source LGPL license, but it now uses a custom license called IUPAC-InChI Trust License. Not all layers have to be provided, for instance, the layer can be omitted if that type of information is not relevant to the particular application. InChIs can thus be seen as akin to a general and extremely formalized version of IUPAC names and they can express more information than the simpler SMILES notation and differ in that every structure has a unique InChI string, which is important in database applications. Information about the 3-dimensional coordinates of atoms is not represented in InChI, the InChI algorithm converts input structural information into a unique InChI identifier in a three-step process, normalization, canonicalization, and serialization. The InChIKey, sometimes referred to as a hashed InChI, is a fixed length condensed digital representation of the InChI that is not human-understandable. The InChIKey specification was released in September 2007 in order to facilitate web searches for chemical compounds and it should be noted that, unlike the InChI, the InChIKey is not unique, though collisions can be calculated to be very rare, they happen. In January 2009 the final 1.02 version of the InChI software was released and this provided a means to generate so called standard InChI, which does not allow for user selectable options in dealing with the stereochemistry and tautomeric layers of the InChI string. The standard InChIKey is then the hashed version of the standard InChI string, the standard InChI will simplify comparison of InChI strings and keys generated by different groups, and subsequently accessed via diverse sources such as databases and web resources. Every InChI starts with the string InChI= followed by the version number and this is followed by the letter S for standard InChIs. The remaining information is structured as a sequence of layers and sub-layers, the layers and sub-layers are separated by the delimiter / and start with a characteristic prefix letter. The six layers with important sublayers are, Main layer Chemical formula and this is the only sublayer that must occur in every InChI. The atoms in the formula are numbered in sequence, this sublayer describes which atoms are connected by bonds to which other ones. Describes how many hydrogen atoms are connected to each of the other atoms, the condensed,27 character standard InChIKey is a hashed version of the full standard InChI, designed to allow for easy web searches of chemical compounds. Most chemical structures on the Web up to 2007 have been represented as GIF files, the full InChI turned out to be too lengthy for easy searching, and therefore the InChIKey was developed. With all databases currently having below 50 million structures, such duplication appears unlikely at present, a recent study more extensively studies the collision rate finding that the experimental collision rate is in agreement with the theoretical expectations. Example, Morphine has the structure shown on the right, as the InChI cannot be reconstructed from the InChIKey, an InChIKey always needs to be linked to the original InChI to get back to the original structure
5.
Simplified molecular-input line-entry system
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The simplified molecular-input line-entry system is a specification in form of a line notation for describing the structure of chemical species using short ASCII strings. SMILES strings can be imported by most molecule editors for conversion back into two-dimensional drawings or three-dimensional models of the molecules, the original SMILES specification was initiated in the 1980s. It has since modified and extended. In 2007, a standard called OpenSMILES was developed in the open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, the original SMILES specification was initiated by David Weininger at the USEPA Mid-Continent Ecology Division Laboratory in Duluth in the 1980s. The Environmental Protection Agency funded the project to develop SMILES. It has since modified and extended by others, most notably by Daylight Chemical Information Systems. In 2007, a standard called OpenSMILES was developed by the Blue Obelisk open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, in July 2006, the IUPAC introduced the InChI as a standard for formula representation. SMILES is generally considered to have the advantage of being slightly more human-readable than InChI, the term SMILES refers to a line notation for encoding molecular structures and specific instances should strictly be called SMILES strings. However, the term SMILES is also used to refer to both a single SMILES string and a number of SMILES strings, the exact meaning is usually apparent from the context. The terms canonical and isomeric can lead to confusion when applied to SMILES. The terms describe different attributes of SMILES strings and are not mutually exclusive, typically, a number of equally valid SMILES strings can be written for a molecule. For example, CCO, OCC and CC all specify the structure of ethanol, algorithms have been developed to generate the same SMILES string for a given molecule, of the many possible strings, these algorithms choose only one of them. This SMILES is unique for each structure, although dependent on the algorithm used to generate it. These algorithms first convert the SMILES to a representation of the molecular structure. A common application of canonical SMILES is indexing and ensuring uniqueness of molecules in a database, there is currently no systematic comparison across commercial software to test if such flaws exist in those packages. SMILES notation allows the specification of configuration at tetrahedral centers, and these are structural features that cannot be specified by connectivity alone and SMILES which encode this information are termed isomeric SMILES
6.
Chemical formula
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These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulas can fully specify the structure of only the simplest of molecules and chemical substances, the simplest types of chemical formulas are called empirical formulas, which use letters and numbers indicating the numerical proportions of atoms of each type. Molecular formulas indicate the numbers of each type of atom in a molecule. For example, the formula for glucose is CH2O, while its molecular formula is C6H12O6. This is possible if the relevant bonding is easy to show in one dimension, an example is the condensed molecular/chemical formula for ethanol, which is CH3-CH2-OH or CH3CH2OH. For reasons of structural complexity, there is no condensed chemical formula that specifies glucose, chemical formulas may be used in chemical equations to describe chemical reactions and other chemical transformations, such as the dissolving of ionic compounds into solution. A chemical formula identifies each constituent element by its chemical symbol, in empirical formulas, these proportions begin with a key element and then assign numbers of atoms of the other elements in the compound, as ratios to the key element. For molecular compounds, these numbers can all be expressed as whole numbers. For example, the formula of ethanol may be written C2H6O because the molecules of ethanol all contain two carbon atoms, six hydrogen atoms, and one oxygen atom. Some types of compounds, however, cannot be written with entirely whole-number empirical formulas. An example is boron carbide, whose formula of CBn is a variable non-whole number ratio with n ranging from over 4 to more than 6.5. When the chemical compound of the consists of simple molecules. These types of formulas are known as molecular formulas and condensed formulas. A molecular formula enumerates the number of atoms to reflect those in the molecule, so that the formula for glucose is C6H12O6 rather than the glucose empirical formula. However, except for very simple substances, molecular chemical formulas lack needed structural information, for simple molecules, a condensed formula is a type of chemical formula that may fully imply a correct structural formula. For example, ethanol may be represented by the chemical formula CH3CH2OH
7.
Conjugate acid
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A conjugate acid, within the Brønsted–Lowry acid–base theory, is a species formed by the reception of a proton by a base—in other words, it is a base with a hydrogen ion added to it. On the other hand, a base is merely what is left after an acid has donated a proton in a chemical reaction. Hence, a base is a species formed by the removal of a proton from an acid. A proton is a particle with a unit positive electrical charge, it is represented by the symbol H+ because it constitutes the nucleus of a hydrogen atom, that is. A cation can be an acid, and an anion can be a conjugate base, depending on which substance is involved. In an acid-base reaction, an acid plus a base reacts to form a conjugate base plus a conjugate acid, refer to the following figure, We say that the water molecule is the conjugate acid of the hydroxide ion after the latter received the hydrogen proton donated by ammonium. On the other hand, ammonia is the base for the acid ammonium after ammonium has donated a hydrogen ion towards the production of the water molecule. The strength of an acid is directly proportional to its dissociation constant. If a conjugate acid is strong, its dissociation will have an equilibrium constant. The strength of a base can be seen as the tendency of the species to pull hydrogen protons towards itself. If a conjugate base is classified as strong, it will hold on to the hydrogen proton when in solution, if a chemical species is classified as a weak acid, its conjugate base will be strong in nature. This can be observed in ammonias reaction with water, the reaction proceeds until most of the ammonia has been transformed to ammonium. This shift to the right in the equilibrium of the reaction means that ammonium does not dissociate easily in water. On the other hand, if a species is classified as a strong acid, an example of this case would be the dissociation of Hydrochloric acid HCl in water. Since HCl is an acid, its conjugate base will be a weak conjugate base. Therefore, in system, most H+ will be in the form of a Hydronium ion H 3O+ instead of attached to a Cl anion. To summarize, the stronger the acid or base, the weaker the conjugate, the acid and conjugate base as well as the base and conjugate acid are known as conjugate pairs. When finding a conjugate acid or base, it is important to look at the reactants of the chemical equation, to identify the conjugate acid, look for the pair of compounds that are related
8.
Salt (chemistry)
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In chemistry, a salt is an ionic compound that results from the neutralization reaction of an acid and a base. Salts are composed of related numbers of cations and anions so that the product is electrically neutral and these component ions can be inorganic, such as chloride, or organic, such as acetate, and can be monatomic, such as fluoride, or polyatomic, such as sulfate. There are several varieties of salts, salts that hydrolyze to produce hydroxide ions when dissolved in water are alkali salts, whilst those that hydrolyze to produce hydronium ions in water are acidic salts. Neutral salts are those salts that are neither acidic nor basic, zwitterions contain an anionic centre and a cationic centre in the same molecule, but are not considered to be salts. Examples of zwitterions include amino acids, many metabolites, peptides, usually, non-dissolved salts at standard conditions for temperature and pressure are solid, but there are exceptions. Molten salts and solutions containing dissolved salts are called electrolytes, as they are able to conduct electricity. As observed in the cytoplasm of cells, in blood, urine, plant saps and mineral waters, therefore, their salt content is given for the respective ions. Salts can appear to be clear and transparent, opaque, and even metallic, in many cases, the apparent opacity or transparency are only related to the difference in size of the individual monocrystals. Since light reflects from the boundaries, larger crystals tend to be transparent. The color of the salt is due to the electronic structure in the d-orbitals of transition elements or in the conjugated organic dye framework. Different salts can elicit all five basic tastes, e. g. salty, sweet, sour, bitter, and umami or savory. Salts of strong acids and strong bases are non-volatile and odorless and that slow, partial decomposition is usually accelerated by the presence of water, since hydrolysis is the other half of the reversible reaction equation of formation of weak salts. Many ionic compounds can be dissolved in water or other similar solvents, the exact combination of ions involved makes each compound have a unique solubility in any solvent. The solubility is dependent on how well each ion interacts with the solvent, for example, all salts of sodium, potassium and ammonium are soluble in water, as are all nitrates and many sulfates – barium sulfate, calcium sulfate and lead sulfate are examples of exceptions. However, ions that bind tightly to each other and form highly stable lattices are less soluble, for example, most carbonate salts are not soluble in water, such as lead carbonate and barium carbonate. Some soluble carbonate salts are, sodium carbonate, potassium carbonate, solid salts do not conduct electricity. Moreover, solutions of salts also conduct electricity, the name of a salt starts with the name of the cation followed by the name of the anion. Salts are often referred to only by the name of the cation or by the name of the anion. g
9.
Alkali metal
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The alkali metals are a group in the periodic table consisting of the chemical elements lithium, sodium, potassium, rubidium, caesium, and francium. Indeed, the alkali metals provide the best example of trends in properties in the periodic table. The alkali metals are all shiny, soft, highly reactive metals at standard temperature and pressure and they can all be cut easily with a knife due to their softness, exposing a shiny surface that tarnishes rapidly in air due to oxidation by atmospheric moisture and oxygen. Because of their reactivity, they must be stored under oil to prevent reaction with air. Caesium, the alkali metal, is the most reactive of all the metals. All the alkali metals react with water, with the alkali metals reacting more vigorously than the lighter ones. Experiments have been conducted to attempt the synthesis of ununennium, which is likely to be the member of the group. Most alkali metals have different applications. One of the applications of the pure elements is the use of rubidium and caesium in atomic clocks, of which caesium atomic clocks are the most accurate. A common application of the compounds of sodium is the sodium-vapour lamp, table salt, or sodium chloride, has been used since antiquity. The physical and chemical properties of the alkali metals can be explained by their having an ns1 valence electron configuration. Hence, all the metals are soft and have low densities, melting and boiling points, as well as heats of sublimation, vaporisation. They all crystallise in the cubic crystal structure, and have distinctive flame colours because their outer s electron is very easily excited. The ns1 configuration also results in the alkali metals having very large atomic and ionic radii, most of the chemistry has been observed only for the first five members of the group. The chemistry of francium is not well established due to its radioactivity, thus. What little is known about francium shows that it is close in behaviour to caesium. The physical properties of francium are even sketchier because the element has never been observed. The alkali metals are more similar to other than the elements in any other group are to each other
10.
Alkaline earth metal
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The alkaline earth metals are six chemical elements in column 2 of the Periodic table. They are beryllium, magnesium, calcium, strontium, barium, the elements have very similar properties, they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure. All the discovered alkaline earth metals occur in nature, experiments have been conducted to attempt the synthesis of element 120, the next potential member of the group, but they have all met with failure. The chemistry of radium is not well-established due to its radioactivity, thus, the alkaline earth metals are all silver-colored and soft, and have relatively low densities, melting points, and boiling points. In chemical terms, all of the alkaline metals react with the halogens to form the earth metal halides. All the alkaline earth metals except beryllium also react with water to form strongly alkaline hydroxides and, thus, the heavier alkaline earth metals react more vigorously than the lighter ones. The second ionization energy of all of the metals is also somewhat low. Beryllium is an exception, It does not react with water or steam, all compounds that include beryllium have a covalent bond. Even the compound beryllium fluoride, which is the most ionic beryllium compound, has a low melting point and a low electrical conductivity when melted. The alkaline earth metals all react with the halogens to form ionic halides, such as calcium chloride, calcium, strontium, and barium react with water to produce hydrogen gas and their respective hydroxides, and also undergo transmetalation reactions to exchange ligands. The table below is a summary of the key physical and atomic properties of the alkaline earth metals, calcium-48 is the lightest nuclide to undergo double beta decay. The natural radioisotope of calcium, calcium-48, makes up about 0. 1874% of natural calcium, barium-130 makes up approximately 0. 1062% of natural barium, and, thus, barium is weakly radioactive, as well. The alkaline earth metals are named after their oxides, the alkaline earths, whose old-fashioned names were beryllia, magnesia, lime, strontia and these oxides are basic when combined with water. Earth is an old term applied by early chemists to nonmetallic substances that are insoluble in water, the realization that these earths were not elements but compounds is attributed to the chemist Antoine Lavoisier. In his Traité Élémentaire de Chimie of 1789 he called them salt-forming earth elements, later, he suggested that the alkaline earths might be metal oxides, but admitted that this was mere conjecture. The calcium compounds calcite and lime have been known and used since prehistoric times, the same is true for the beryllium compounds beryl and emerald. The other compounds of the alkaline earth metals were discovered starting in the early 15th century, the magnesium compound magnesium sulfate was first discovered in 1618 by a farmer at Epsom in England. Strontium carbonate was discovered in minerals in the Scottish village of Strontian in 1790, the last element is the least abundant, radioactive radium, which was extracted from uraninite in 1898
11.
Transition metal
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Many scientists describe a transition metal as any element in the d-block of the periodic table, which includes groups 3 to 12 on the periodic table. In actual practice, the lanthanide and actinide series are also considered transition metals and are called inner transition metals. Cotton and Wilkinson expand the brief IUPAC definition by specifying which elements are included, as well as the elements of groups 4 to 11, they add scandium and yttrium in group 3 which have a partially filled d subshell in the metallic state. These last two elements are included even though they do not seem to possess the properties which are so characteristic of the transition metals in general. Lanthanum and actinium in Group 3 are however classified as lanthanides and actinides respectively and these elements are now known as the d-block. In the d-block the atoms of the elements have between 1 and 10 d electrons, Sc and Y in Group 3 are also generally recognized as transition metals. However the elements La–Lu and Ac–Lr and Group 12 attract different definitions from different authors, many chemistry textbooks and printed periodic tables classify La and Ac as Group 3 elements and transition metals, since their atomic ground-state configurations are s2d1 like Sc and Y. The elements Ce-Lu are considered as the series and Th-Lr as the actinide series. The two series together are classified as elements, or as inner transition elements. Some inorganic chemistry textbooks include La with the lanthanides and Ac with the actinides, a third classification defines the f-block elements as La-Yb and Ac-No, while placing Lu and Lr in Group 3. This is based on the Aufbau principle for filling electron subshells, in which 4f is filled before 5d, zinc, cadmium, and mercury are generally excluded from the transition metals as they have the electronic configuration d10s2, with no incomplete d shell. In the oxidation state +2 the ions have the electronic configuration d10, however, these elements can exist in other oxidation states, including the +1 oxidation state, as in the diatomic ion Hg2+2. The group 12 elements Zn, Cd and Hg may therefore, under certain rules, however, it is often convenient to include these elements in a discussion of the transition elements. Another example occurs in the Irving-Williams series of stability constants of complexes, although meitnerium, darmstadtium, and roentgenium are within the d-block and are expected to behave as transition metals, this has not yet been experimentally confirmed. The general electronic configuration of the elements is d1, 10n s1,2. The period 6 and 7 transition metals also add f1,14 electrons and this rule is however only approximate – it only holds for some of the transition elements, and only then in their neutral ground state. The d-sub-shell is the next-to-last sub-shell and is denoted as d -sub-shell, the number of s electrons in the outermost s sub-shell is generally one or two except palladium, with no electron in that s-sub shell in its ground state. The s-sub-shell in the shell is represented as the ns sub-shell
12.
Nonmetal
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In chemistry, a nonmetal is a chemical element that mostly lacks metallic attributes. Seventeen elements are classified as nonmetals, most are gases, one is a liquid. Moving rightward across the standard form of the table, nonmetals adopt structures that have progressively fewer nearest neighbours. Polyatomic nonmetals have structures with either three nearest neighbours, as is the case with carbon, or two nearest neighbours in the case of sulfur, diatomic nonmetals, such as hydrogen, have one nearest neighbour, and the monatomic noble gases, such as helium, have none. This gradual fall in the number of nearest neighbours is associated with a reduction in metallic character, the distinction between the three categories of nonmetals, in terms of receding metallicity is not absolute. Boundary overlaps occur as outlying elements in each category show less-distinct, living organisms are also composed almost entirely of nonmetals, and nonmetals form many more compounds than metals. There is no definition of a nonmetal. They show more variability in their properties than metals do, the following are some of the chief characteristics of nonmetals. The elements generally classified as nonmetals include one element in group 1, one in group 14, the distinction between nonmetals and metals is by no means clear. Nonmetals have structures in each atom usually forms bonds with nearest neighbours. Each atom is able to complete its valence shell and attain a stable noble gas configuration. Exceptions to the rule occur with hydrogen, carbon, nitrogen and oxygen, atoms of the latter three elements are sufficiently small such that they are able to form alternative bonding structures, with fewer nearest neighbours. Thus, carbon is able to form its layered graphite structure, the larger size of the remaining non-noble nonmetals weakens their capacity to form multiple bonds and they instead form two or more single bonds to two or more different atoms. Sulfur, for example, forms an eight-membered molecule in which the atoms are arranged in a ring, a similar pattern occurs more generally, at the level of the entire periodic table, in comparing metals and nonmetals. There is a transition from metallic bonding among the metals on the left of the table through to covalent or Van der Waals bonding among the nonmetals on the right of the table, metallic bonding tends to involve close-packed centrosymmetric structures with a high number of nearest neighbours. Post-transition metals and metalloids, sandwiched between the metals and the nonmetals, tend to have more complex structures with an intermediate number of nearest neighbours. Nonmetallic bonding, towards the right of the table, features open-packed directional structures with fewer or zero nearest neighbours, as is the case with the major categories of metals, metalloids and nonmetals, there is some variation and overlapping of properties within and across each category of nonmetal. Among the polyatomic nonmetals, carbon, phosphorus and selenium—which border the metalloids—begin to show some metallic character, sulfur, is the least metallic of the polyatomic nonmetals but even here shows some discernible metal-like character
13.
Radical (chemistry)
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In chemistry, a radical is an atom, molecule, or ion that has an unpaired valence electron. Most radicals are reasonably stable only at low concentrations in inert media or in a vacuum. A notable example of a radical is the hydroxyl radical. Two other examples are triplet oxygen and triplet carbene which have two unpaired electrons, free radicals may be created in a number of ways, including synthesis with very dilute or rarefied reagents, reactions at very low temperatures, or breakup of larger molecules. The latter can be affected by any process that puts energy into the parent molecule, such as ionizing radiation, heat, electrical discharges, electrolysis. Radicals are intermediate stages in many chemical reactions, free radicals play an important role in combustion, atmospheric chemistry, polymerization, plasma chemistry, biochemistry, and many other chemical processes. In living organisms, the free radicals superoxide and nitric oxide and their reaction products regulate many processes, such as control of vascular tone and they also play a key role in the intermediary metabolism of various biological compounds. Such radicals can even be messengers in a process dubbed redox signaling, a radical may be trapped within a solvent cage or be otherwise bound. The qualifier free was then needed to specify the unbound case, following recent nomenclature revisions, a part of a larger molecule is now called a functional group or substituent, and radical now implies free. However, the old nomenclature may still appear in some books, the term radical was already in use when the now obsolete radical theory was developed. Louis-Bernard Guyton de Morveau introduced the phrase radical in 1785 and the phrase was employed by Antoine Lavoisier in 1789 in his Traité Élémentaire de Chimie, a radical was then identified as the root base of certain acids. Historically, the radical in radical theory was also used for bound parts of the molecule. These are now called functional groups, for example, methyl alcohol was described as consisting of a methyl radical and a hydroxyl radical. In a modern context the first organic free radical identified was triphenylmethyl radical and this species was discovered by Moses Gomberg in 1900 at the University of Michigan USA. In 1933 Morris Kharash and Frank Mayo proposed that free radicals were responsible for anti-Markovnikov addition of hydrogen bromide to allyl bromide. It should be noted that the electron of the breaking bond also moves to pair up with the attacking radical electron. Free radicals also take part in addition and radical substitution as reactive intermediates. Chain reactions involving free radicals can usually be divided into three distinct processes and these are initiation, propagation, and termination
14.
Ion
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An ion is an atom or a molecule in which the total number of electrons is not equal to the total number of protons, giving the atom or molecule a net positive or negative electrical charge. Ions can be created, by chemical or physical means. In chemical terms, if an atom loses one or more electrons. If an atom gains electrons, it has a net charge and is known as an anion. Ions consisting of only a single atom are atomic or monatomic ions, because of their electric charges, cations and anions attract each other and readily form ionic compounds, such as salts. In the case of ionization of a medium, such as a gas, which are known as ion pairs are created by ion impact, and each pair consists of a free electron. The word ion comes from the Greek word ἰόν, ion, going and this term was introduced by English physicist and chemist Michael Faraday in 1834 for the then-unknown species that goes from one electrode to the other through an aqueous medium. Faraday also introduced the words anion for a charged ion. In Faradays nomenclature, cations were named because they were attracted to the cathode in a galvanic device, arrhenius explanation was that in forming a solution, the salt dissociates into Faradays ions. Arrhenius proposed that ions formed even in the absence of an electric current, ions in their gas-like state are highly reactive, and do not occur in large amounts on Earth, except in flames, lightning, electrical sparks, and other plasmas. These gas-like ions rapidly interact with ions of charge to give neutral molecules or ionic salts. These stabilized species are commonly found in the environment at low temperatures. A common example is the present in seawater, which are derived from the dissolved salts. Electrons, due to their mass and thus larger space-filling properties as matter waves, determine the size of atoms. Thus, anions are larger than the parent molecule or atom, as the excess electron repel each other, as such, in general, cations are smaller than the corresponding parent atom or molecule due to the smaller size of its electron cloud. One particular cation contains no electrons, and thus consists of a single proton - very much smaller than the parent hydrogen atom. Since the electric charge on a proton is equal in magnitude to the charge on an electron, an anion, from the Greek word ἄνω, meaning up, is an ion with more electrons than protons, giving it a net negative charge. A cation, from the Greek word κατά, meaning down, is an ion with fewer electrons than protons, there are additional names used for ions with multiple charges
15.
Aqueous solution
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An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending to the relevant chemical formula, for example, a solution of table salt, or sodium chloride, in water would be represented as Na+ + Cl−. The word aqueous means pertaining to, related to, similar to, as water is an excellent solvent and is also naturally abundant, it is a ubiquitous solvent in chemistry. Substances that are hydrophobic often do not dissolve well in water, an example of a hydrophilic substance is sodium chloride. Acids and bases are aqueous solutions, as part of their Arrhenius definitions, the ability of a substance to dissolve in water is determined by whether the substance can match or exceed the strong attractive forces that water molecules generate between themselves. If the substance lacks the ability to dissolve in water the molecules form a precipitate, reactions in aqueous solutions are usually metathesis reactions. Metathesis reactions are another term for double-displacement, that is, when a cation displaces to form a bond with the other anion. The cation bonded with the latter anion will dissociate and bond with the other anion, aqueous solutions that conduct electric current efficiently contain strong electrolytes, while ones that conduct poorly are considered to have weak electrolytes. Those strong electrolytes are substances that are ionized in water. Nonelectrolytes are substances that dissolve in water yet maintain their molecular integrity, examples include sugar, urea, glycerol, and methylsulfonylmethane. When writing the equations of reactions, it is essential to determine the precipitate. To determine the precipitate, one must consult a chart of solubility, soluble compounds are aqueous, while insoluble compounds are the precipitate. Remember that there may not always be a precipitate, when performing calculations regarding the reacting of one or more aqueous solutions, in general one must know the concentration, or molarity, of the aqueous solutions. Solution concentration is given in terms of the form of the prior to it dissolving. Metal ions in aqueous solution Solubility Dissociation Acid-base reaction theories Properties of water Zumdahl S.1997, 4th ed. Boston, Houghton Mifflin Company
16.
Ester
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In chemistry, esters are chemical compounds derived from an acid in which at least one –OH group is replaced by an –O–alkyl group. Usually, esters are derived from an acid and an alcohol. Glycerides, which are fatty acid esters of glycerol, are important esters in biology, being one of the classes of lipids. Esters with low weight are commonly used as fragrances and found in essential oils. Phosphoesters form the backbone of DNA molecules, nitrate esters, such as nitroglycerin, are known for their explosive properties, while polyesters are important plastics, with monomers linked by ester moieties. The word ester was coined in 1848 by German chemist Leopold Gmelin, probably as a contraction of the German Essigäther, ester names are derived from the parent alcohol and the parent acid, where the latter may be organic or inorganic. Esters derived from more complex carboxylic acids are, on the hand, more frequently named using the systematic IUPAC name. For example, the ester hexyl octanoate, also known under the trivial name hexyl caprylate, has the formula CH36CO25CH3, the chemical formulas of organic esters usually take the form RCO2R′, where R and R′ are the hydrocarbon parts of the carboxylic acid and the alcohol, respectively. For example, butyl acetate, derived from butanol and acetic acid would be written CH3CO2C4H9, alternative presentations are common including BuOAc and CH3COOC4H9. Cyclic esters are called lactones, regardless of whether they are derived from an organic or an inorganic acid, one example of a lactone is γ-valerolactone. An uncommon class of organic esters are the orthoesters, which have the formula RC3, triethylorthoformate is derived, in terms of its name from orthoformic acid and ethanol. Esters can also be derived from an acid and an alcohol. For example, triphenyl phosphate is the derived from phosphoric acid. Organic carbonates are derived from acid, for example, ethylene carbonate is derived from carbonic acid. So far an alcohol and inorganic acid are linked via oxygen atoms, in corollary, boron features borinic esters, boronic esters, and borates. As oxygen is a group 16 chemical element, sulfur atoms can replace some oxygen atoms in carbon–oxygen–central inorganic atom covalent bonds of an ester, esters contain a carbonyl center, which gives rise to 120 ° C–C–O and O–C–O angles. Unlike amides, esters are structurally flexible functional groups because rotation about the C–O–C bonds has a low barrier and their flexibility and low polarity is manifested in their physical properties, they tend to be less rigid and more volatile than the corresponding amides. The pKa of the alpha-hydrogens on esters is around 25, the preference for the Z conformation is influenced by the nature of the substituents and solvent, if present
17.
Polyatomic ion
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The prefix poly- means many, in Greek, but even ions of two atoms are commonly referred to as polyatomic. In older literature, an ion is also referred to as a radical. In contemporary usage, the term refers to free radicals that are species with an unpaired electron. An example of an ion is the hydroxide ion, consisting of one oxygen atom and one hydrogen atom. An ammonium ion is made up of one atom and four hydrogen atoms, it has a charge of +1. Polyatomic ions are often useful in the context of chemistry or in the formation of salts. A polyatomic ion can often be considered as the conjugate acid/base of a neutral molecule, for example, the conjugate base of sulfuric acid is the polyatomic hydrogen sulfate anion. The removal of hydrogen ion yields the sulfate anion. There are two rules that can be used for learning the nomenclature of polyatomic anions. First, when the prefix bi is added to a name, a hydrogen is added to the formula and its charge is increased by 1. An alternative to the bi- prefix is to use the hydrogen in its place. Note that many of the common polyatomic anions are conjugate bases of acids derived from the oxides of non-metallic elements, for example, the sulfate anion, SO42−, is derived from H 2SO4, which can be regarded as SO3 + H 2O. The second rule looks at the number of oxygens in an ion, consider the chlorine oxoanion family, First, think of the -ate ion as being the base name, in which case the addition of a per- prefix adds an oxygen. Changing the -ate suffix to -ite will reduce the oxygens by one, in all situations, the charge is not affected. The naming pattern follows within many different oxyanion series based on a root for that particular series. The -ite has one less oxygen than the -ate, but different -ate anions might have different numbers of oxygen atoms and these rules will not work with all polyatomic anions, but they do work with the most common ones. The following tables give examples of commonly encountered polyatomic ions, only a few representatives are given, as the number of polyatomic ions encountered in practice is very large. Monatomic ions Salt Mass spectrometry Hydrogen peroxide Molecule Hydrogen molecular ion List of polyatomic ions A Beginners Guide To Polyatomic Ions, tables of Common Polyatomic Ions, including PDB files
18.
Polymer
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A polymer is a large molecule, or macromolecule, composed of many repeated subunits. Because of their range of properties, both synthetic and natural polymers play an essential and ubiquitous role in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure, Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. The units composing polymers derive, actually or conceptually, from molecules of low molecular mass. The term was coined in 1833 by Jöns Jacob Berzelius, though with a distinct from the modern IUPAC definition. The modern concept of polymers as covalently bonded macromolecular structures was proposed in 1920 by Hermann Staudinger, Polymers are studied in the fields of biophysics and macromolecular science, and polymer science. Polyisoprene of latex rubber is an example of a polymer. In biological contexts, essentially all biological macromolecules—i. e, proteins, nucleic acids, and polysaccharides—are purely polymeric, or are composed in large part of polymeric components—e. g. Isoprenylated/lipid-modified glycoproteins, where small molecules and oligosaccharide modifications occur on the polyamide backbone of the protein. The simplest theoretical models for polymers are ideal chains, Polymers are of two types, Natural polymeric materials such as shellac, amber, wool, silk and natural rubber have been used for centuries. A variety of natural polymers exist, such as cellulose. Most commonly, the continuously linked backbone of a used for the preparation of plastics consists mainly of carbon atoms. A simple example is polyethylene, whose repeating unit is based on ethylene monomer, however, other structures do exist, for example, elements such as silicon form familiar materials such as silicones, examples being Silly Putty and waterproof plumbing sealant. Oxygen is also present in polymer backbones, such as those of polyethylene glycol, polysaccharides. Polymerization is the process of combining many small molecules known as monomers into a covalently bonded chain or network, during the polymerization process, some chemical groups may be lost from each monomer. This is the case, for example, in the polymerization of PET polyester, the distinct piece of each monomer that is incorporated into the polymer is known as a repeat unit or monomer residue. Laboratory synthetic methods are divided into two categories, step-growth polymerization and chain-growth polymerization. However, some methods such as plasma polymerization do not fit neatly into either category
19.
Biosynthesis
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Biosynthesis is a multi-step, enzyme-catalyzed process where substrates are converted into more complex products in living organisms. In biosynthesis, simple compounds are modified, converted into other compounds and this process often consists of metabolic pathways. Some of these pathways are located within a single cellular organelle, while others involve enzymes that are located within multiple cellular organelles. Examples of these pathways include the production of lipid membrane components. The prerequisite elements for biosynthesis include, precursor compounds, chemical energy and these elements create monomers, the building blocks for macromolecules. Biosynthesis occurs due to a series of chemical reactions, for these reactions to take place, the following elements are necessary, Precursor compounds, these compounds are the starting molecules or substrates in a reaction. These may also be viewed as the reactants in a chemical process. Chemical energy, chemical energy can be found in the form of high energy molecules and these molecules are required for energetically unfavorable reactions. Furthermore, the hydrolysis of these compounds drives a reaction forward, high energy molecules, such as ATP, have three phosphates. Often, the phosphate is split off during hydrolysis and transferred to another molecule. Catalytic enzymes, these molecules are special proteins that catalyze a reaction by increasing the rate of the reaction, coenzymes or cofactors, cofactors are molecules that assist in chemical reactions. These may be metal ions, vitamin derivatives such as NADH and acetyl CoA, in the case of NADH, the molecule transfers a hydrogen, whereas acetyl CoA transfers an acetyl group, and ATP transfers a phosphate. Two examples of type of reaction occur during the formation of nucleic acids. For some of these steps, chemical energy is required, Precursor molecule + ATP ↽ − − ⇀ product AMP + PP i Simple compounds that are converted into other compounds with the assistance of cofactors. For example, the synthesis of phospholipids requires acetyl CoA, while the synthesis of another component, shingolipids. The general equation for these examples is, Precursor molecule + Cofactor → e n z y m e macromolecule Simple compounds that join together to create a macromolecule, for example, fatty acids join together to form phopspholipids. In turn, phospholipids and cholesterol interact noncovalently in order to form the lipid bilayer and this reaction may be depicted as follows, Molecule 1 + Molecule 2 ⟶ macromolecule Many intricate macromolecules are synthesized in a pattern of simple, repeated structures. For example, the simplest structures of lipids are fatty acids, fatty acids are hydrocarbon derivatives, they contain a carboxyl group “head” and a hydrocarbon chain “tail. ”These fatty acids create larger components, which in turn incorporate noncovalent interactions to form the lipid bilayer
20.
Fatty acid
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In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with a long aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms. Fatty acids are derived from triglycerides or phospholipids. Fatty acids are important dietary sources of fuel for animals because, many cell types can use either glucose or fatty acids for this purpose. Fatty acids that have double bonds are known as unsaturated. Fatty acids without double bonds are known as saturated and they differ in length as well. Fatty acid chains differ by length, often categorized as short to very long, short-chain fatty acids are fatty acids with aliphatic tails of five or fewer carbons. Medium-chain fatty acids are fatty acids with aliphatic tails of 6–12 carbons, long-chain fatty acids are fatty acids with aliphatic tails of 13 to 21 carbons. Very long chain fatty acids are fatty acids with aliphatic tails of 22 or more carbons, unsaturated fatty acids have one or more double bonds between carbon atoms. The two carbon atoms in the chain that are next to either side of the double bond can occur in a cis or trans configuration. Cis A cis configuration means that the two atoms adjacent to the double bond stick out on the same side of the chain. The rigidity of the double bond freezes its conformation and, in the case of the cis isomer, causes the chain to bend, the more double bonds the chain has in the cis configuration, the less flexibility it has. When a chain has many cis bonds, it becomes quite curved in its most accessible conformations, for example, oleic acid, with one double bond, has a kink in it, whereas linoleic acid, with two double bonds, has a more pronounced bend. α-Linolenic acid, with three bonds, favors a hooked shape. Trans A trans configuration, by contrast, means that the adjacent two hydrogen atoms lie on opposite sides of the chain, as a result, they do not cause the chain to bend much, and their shape is similar to straight saturated fatty acids. In most naturally occurring unsaturated fatty acids, each bond has three n carbon atoms after it, for some n, and all are cis bonds. Most fatty acids in the configuration are not found in nature and are the result of human processing. Fatty acids that are required by the body but cannot be made in sufficient quantity from other substrates
21.
Salt
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Salt is present in vast quantities in seawater, where it is the main mineral constituent. The open ocean has about 35 grams of solids per litre, Salt is essential for life in general, and saltiness is one of the basic human tastes. The tissues of animals contain larger quantities of salt than do plant tissues, Salt is one of the oldest and most ubiquitous food seasonings, and salting is an important method of food preservation. Salt was also prized by the ancient Hebrews, the Greeks, the Romans, the Byzantines, the Hittites, Egyptians, and the Indians. Salt became an important article of trade and was transported by boat across the Mediterranean Sea, along specially built salt roads, the scarcity and universal need for salt has led nations to go to war over it and use it to raise tax revenues. Salt is used in ceremonies and has other cultural significance. Salt is processed from salt mines, or by the evaporation of seawater or mineral-rich spring water in shallow pools. Its major industrial products are caustic soda and chlorine, and is used in industrial processes including the manufacture of polyvinyl chloride, plastics, paper pulp. Of the annual production of around two hundred million tonnes of salt, only about 6% is used for human consumption. Other uses include water conditioning processes, de-icing highways, and agricultural use, edible salt is sold in forms such as sea salt and table salt which usually contains an anti-caking agent and may be iodised to prevent iodine deficiency. As well as its use in cooking and at the table, sodium is an essential nutrient for human health via its role as an electrolyte and osmotic solute. Excessive salt consumption can increase the risk of diseases, such as hypertension, in children. Such health effects of salt have long been studied, accordingly, numerous world health associations and experts in developed countries recommend reducing consumption of popular salty foods. The World Health Organization recommends that adults should consume less than 2,000 mg of sodium, humans have always tended to build communities either around sources of salt, or where they can trade for it. All through history the availability of salt has been pivotal to civilization, the word salary comes from the Latin word for salt because the Roman Legions were sometimes paid in salt. The Natron Valley was a key region that supported the Egyptian Empire to its north, because it supplied it with a kind of salt that came to be called by its name, natron. Even before this, what is now thought to have been the first city in Europe is Solnitsata, in Bulgaria, even the name Solnisata means salt works. A very ancient salt-works operation has been discovered at the Poiana Slatinei archaeological site next to a spring in Lunca, Neamț County
22.
Sodium acetate
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Sodium acetate, CH3COONa, also abbreviated NaOAc, also known as sodium ethanoate, is the sodium salt of acetic acid. This colorless deliquescent salt has a range of uses. Sodium acetate is used in the industry to neutralize sulfuric acid waste streams. It is also an agent in chrome tanning and helps to impede vulcanization of chloroprene in synthetic rubber production. In processing cotton for disposable cotton pads, sodium acetate is used to eliminate the buildup of static electricity. Sodium acetate may be added to food as a seasoning, sometimes in the form of sodium diacetate and it is often used to give potato chips a salt and vinegar flavor. As the conjugate base of acetic acid, a solution of sodium acetate and this is useful especially in biochemical applications where reactions are pH-dependent in a mildly acidic range. Sodium acetate is used in heating pads, hand warmers. Sodium acetate trihydrate crystals melt at 136.4 °F/58 °C, when they are heated past the melting point and subsequently allowed to cool, the aqueous solution becomes supersaturated. This solution is capable of cooling to room temperature without forming crystals, by pressing on a metal disc within the heating pad, a nucleation center is formed, causing the solution to crystallize back into solid sodium acetate trihydrate. The bond-forming process of crystallization is exothermic, the latent heat of fusion is about 264–289 kJ/kg. For laboratory use, sodium acetate is inexpensive and usually purchased instead of being synthesized and it is sometimes produced in a laboratory experiment by the reaction of acetic acid, commonly in the 5–8% solution known as vinegar, with sodium carbonate, sodium bicarbonate, or sodium hydroxide. Any of these reactions produce sodium acetate and water, carbonic acid readily decomposes under normal conditions into gaseous carbon dioxide and water. This is the taking place in the well-known volcano that occurs when the household products, baking soda. CH3COOH + NaHCO3 → CH3COONa + H2CO3 H2CO3 → CO2 + H 2O Industrially, sodium acetate is prepared from glacial acetic acid and sodium hydroxide. CH3COOH + NaOH → CH3COONa + H2O Sodium acetate can be used to form an ester with an alkyl halide such as bromoethane, hot Ice – Instructions, Pictures, and Videos How Sodium Acetate heating pads work
23.
Ethyl acetate
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Ethyl acetate is the organic compound with the formula CH3–COO–CH2–CH3, simplified to C4H8O2. This colorless liquid has a sweet smell and is used in glues, nail polish removers, decaffeinating tea and coffee. Ethyl acetate is the ester of ethanol and acetic acid, it is manufactured on a scale for use as a solvent. The combined annual production in 1985 of Japan, North America, in 2004, an estimated 1.3 million tonnes were produced worldwide. Ethyl acetate is synthesized in industry mainly via the classic Fischer esterification reaction of ethanol and this method is more cost effective than the esterification but is applied with surplus ethanol in a chemical plant. Typically, dehydrogenation is conducted with copper at an elevated temperature, the copper may have its surface area increased by depositing it on zinc, promoting the growth of snowflake-like fractal structures. Surface area can be increased by deposition onto a zeolite. Traces of rare earth and alkali metals are beneficial to the process, byproducts of the dehydrogenation include diethyl ether, which is thought to arise primarily due to aluminum sites in the catalyst, acetaldehyde and its aldol products, higher esters, and ketones. These azeotropes are broken by pressure swing distillation or membrane distillation, ethyl acetate is used primarily as a solvent and diluent, being favored because of its low cost, low toxicity, and agreeable odor. For example, it is used to clean circuit boards. Coffee beans and tea leaves are decaffeinated with this solvent and it is also used in paints as an activator or hardener. Ethyl acetate is present in confectionery, perfumes, and fruits, in perfumes, it evaporates quickly, leaving only the scent of the perfume on the skin. In the laboratory, mixtures containing ethyl acetate are used in column chromatography. Ethyl acetate is rarely selected as a solvent because it is prone to hydrolysis. Ethyl acetate is volatile at room temperature and has a boiling point of 77 °C. Due to these properties, it can be removed from a sample by heating in a hot water bath and providing ventilation with compressed air. Ethyl acetate is the most common ester in wine, being the product of the most common organic acid – acetic acid. The aroma of ethyl acetate is most vivid in younger wines and contributes towards the general perception of fruitiness in the wine, sensitivity varies, with most people having a perception threshold around 120 mg/L
24.
Actinium
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Actinium is a radioactive chemical element with symbol Ac and atomic number 89, which was discovered in 1899. It was the first non-primordial radioactive element to be isolated, polonium, radium and radon were observed before actinium, but they were not isolated until 1902. Actinium gave the name to the series, a group of 15 similar elements between actinium and lawrencium in the periodic table. It is also considered the first of the 7th-period transition metals. A soft, silvery-white radioactive metal, actinium reacts rapidly with oxygen, as with most lanthanides and many actinides, actinium assumes oxidation state +3 in nearly all its chemical compounds. One tonne of uranium in ore contains about 0.2 milligrams of actinium-227. The close similarity of physical and chemical properties of actinium and lanthanum makes separation of actinium from the ore impractical, instead, the element is prepared, in milligram amounts, by the neutron irradiation of 226Ra in a nuclear reactor. Owing to its scarcity, high price and radioactivity, actinium has no significant industrial use and its current applications include a neutron source and an agent for radiation therapy targeting cancer cells in the body. André-Louis Debierne, a French chemist, announced the discovery of a new element in 1899 and he separated it from pitchblende residues left by Marie and Pierre Curie after they had extracted radium. In 1899, Debierne described the substance as similar to titanium, friedrich Oskar Giesel independently discovered actinium in 1902 as a substance being similar to lanthanum and called it emanium in 1904. Articles published in the 1970s and later suggest that Debiernes results published in 1904 conflict with those reported in 1899 and 1900 and this has led some authors to advocate that Giesel alone should be credited with the discovery. A less confrontational vision of scientific discovery is proposed by Adloff, Debierne, who is now considered by the vast majority of historians as the discoverer, lost interest in the element and left the topic. Giesel, on the hand, can rightfully be credited with the first preparation of radiochemically pure actinium. The name actinium originates from the Ancient Greek aktis, aktinos and its symbol Ac is also used in abbreviations of other compounds that have nothing to do with actinium, such as acetyl, acetate and sometimes acetaldehyde. Actinium is a soft, silvery-white, radioactive, metallic element and its estimated shear modulus is similar to that of lead. Owing to its radioactivity, actinium glows in the dark with a pale blue light. Actinium has similar properties to lanthanum and other lanthanides. Solvent extraction and ion chromatography are commonly used for the separation, the first element of the actinides, actinium gave the group its name, much as lanthanum had done for the lanthanides
25.
Actinide
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The actinide /ˈæktᵻnaɪd/ or actinoid /ˈæktᵻnɔɪd/ series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium. The actinide series derives its name from the first element in the series, the informal chemical symbol An is used in general discussions of actinide chemistry to refer to any actinide. All but one of the actinides are f-block elements, corresponding to the filling of the 5f electron shell, lawrencium, in comparison with the lanthanides, also mostly f-block elements, the actinides show much more variable valence. They all have very large atomic and ionic radii and exhibit a large range of physical properties. While actinium and the late actinides behave similarly to the lanthanides, all actinides are radioactive and release energy upon radioactive decay, naturally occurring uranium and thorium, and synthetically produced plutonium are the most abundant actinides on Earth. These are used in nuclear reactors and nuclear weapons, uranium and thorium also have diverse current or historical uses, and americium is used in the ionization chambers of most modern smoke detectors. Of the actinides, primordial thorium and uranium occur naturally in substantial quantities, the radioactive decay of uranium produces transient amounts of actinium and protactinium, and atoms of neptunium and plutonium are occasionally produced from transmutation reactions in uranium ores. The other actinides are purely synthetic elements, like the lanthanides, the actinides form a family of elements with similar properties. Within the actinides, there are two overlapping groups, transuranium elements, which follow uranium in the periodic table—and transplutonium elements, compared to the lanthanides, which are found in nature in appreciable quantities, most actinides are rare. The most abundant, or easily synthesized actinides are uranium and thorium, the existence of transuranium elements was suggested by Enrico Fermi based on his experiments in 1934. However, even though four actinides were known by that time, synthesis of transuranics gradually undermined this point of view. By 1944 an observation that curium failed to exhibit oxidation states above 4 prompted Glenn Seaborg to formulate a so-called actinide hypothesis, at present, there are two major methods of producing isotopes of transplutonium elements, irradiation of the lighter elements with either neutrons or accelerated charged particles. The advantage of the method is that elements heavier than plutonium, as well as neutron-deficient isotopes, can be obtained. In 1962–1966, there were attempts in the United States to produce transplutonium isotopes using a series of six underground nuclear explosions and this inobservation was attributed to spontaneous fission owing to the large speed of the products and to other decay channels, such as neutron emission and nuclear fission. Uranium and thorium were the first actinides discovered, uranium was identified in 1789 by the German chemist Martin Heinrich Klaproth in pitchblende ore. He named it after the planet Uranus, which had been discovered eight years earlier. Klaproth was able to precipitate a yellow compound by dissolving pitchblende in nitric acid and he then reduced the obtained yellow powder with charcoal, and extracted a black substance that he mistook for metal. Only 60 years later, the French scientist Eugène-Melchior Péligot identified it with uranium oxide and he also isolated the first sample of uranium metal by heating uranium tetrachloride with potassium
26.
Peracetic acid
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Peracetic acid, is an organic compound with the formula CH3CO3H. This organic peroxide is a liquid with a characteristic acrid odor reminiscent of acetic acid. Peracetic acid is an acid than the parent acetic acid. Peracetic acid is generated in situ by some laundry detergents, PAA is also formed naturally in the environment through a series of photochemical reactions involving formaldehyde and photo-oxidant radicals. Peracetic acid is sold in solution with acetic acid and hydrogen peroxide to maintain the stability of the peracid. The concentration of the acid as the ingredient can vary. The United States Environmental Protection Agency first registered peracetic acid as an antimicrobial in 1985 for indoor use on hard surfaces, use sites include agricultural premises, food establishments, medical facilities, and home bathrooms. Peracetic acid is also registered for use in processing plants, on food processing equipment, and in pasteurizers in breweries, wineries. It is also applied for the disinfection of medical supplies, to prevent biofilm formation in pulp industries, peracetic acid can be used as a cooling tower water disinfectant, where it prevents bio film formation and effectively controls Legionella bacteria. A trade name for peracetic acid as an antimicrobial is Nu-Cidex, although less active than more acidic peracids, peracetic acid in various forms is used for the epoxidation of various alkenes. Useful application are for unsaturated fats, synthetic and natural rubbers, a variety of factors affect the amount of free acid or sulfuric acid. Peracetic acid is an oxidizing agent and a primary irritant. Exposure to peracetic acid can cause irritation to the skin, eyes and respiratory system, in addition, there have been cases of occupational asthma caused by peracetic acid. The ACGIH has published a STEL TLV for peracetic acid of 0.4 ppm, currently there is no OSHA Permissible Exposure Limit for peracetic acid. In 2010, the US EPA published Acute Exposure Guidelines for peracetic acid, disinfectant Hydroxyl Organic peroxide Peroxy acid
27.
Carboxylate
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A carboxylate is a salt or ester of a carboxylic acid. Carboxylate salts have the general formula Mn, where M is a metal, carboxylate esters have the general formula RCOOR′. R and R′ are organic groups, R′ ≠ H, a carboxylate ion is the conjugate base of a carboxylic acid, RCOO−. It is an ion with negative charge, carboxylic acids easily dissociate into a carboxylate anion and a positively charged hydrogen ion, much more readily than alcohols do, because the carboxylate ion is stabilized by resonance. The negative charge that is left after deprotonation of the group is delocalized between the two electronegative oxygen atoms in a resonance structure. In contrast, an ion, once formed, would have a strong negative charge on the oxygen atom. Carboxylic acids thus have a lower pH than alcohols, the higher the number of protons in solution, formate ion, HCOO− Acetate ion, CH3COO− Lactate ion, CH3CHCOO− Oxalate ion, 2−2 Citrate ion, C 3H 5O3−3
28.
Chromium(II) acetate
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Chromium acetate hydrate, also known as chromous acetate, is the coordination compound with the formula Cr242. This formula is commonly abbreviated Cr242 and this red-coloured compound features a quadruple bond. The preparation of chromous acetate once was a standard test of the skills of students due to its sensitivity to air. It exists as the dihydrate and the anhydrous forms, Cr242 is a reddish diamagnetic powder, although diamond-shaped tabular crystals can be grown. Consistent with the fact that it is nonionic, Cr242 exhibits poor solubility in water, the Cr242 molecule contains two atoms of chromium, two ligated molecules of water, and four monoanionic acetate bridging ligands. The coordination environment around each chromium atom consists of four atoms in a square, one water molecule. The chromium atoms are joined together by a bond. The same basic structure is adopted by Rh242 and Cu242, although these species do not have such short M–M contacts and this quadruple bond is also confirmed by the low magnetic moment and short intermolecular distance between the two atoms of 236.2 ±0.1 pm. The Cr–Cr distances are even shorter,184 pm being the record, eugène-Melchior Péligot first reported a chromium acetate in 1844. His material was apparently the dimeric Cr242, the unusual structure, as well as that of copper acetate, was uncovered in 1951. An aqueous solution of a Cr compound is first reduced to the state using zinc. The resulting blue solution is treated with sodium acetate, which results in the precipitation of chromous acetate as a bright red powder. Because it is so prepared, Cr242 is often used as a starting material for other. Also many analogues have been prepared using other carboxylic acids in place of acetate, Cr242 is used occasionally to dehalogenate organic compounds such as α-bromoketones and chlorohydrins. The reactions appear to proceed via 1e− steps, and rearrangement products are sometimes observed, because the molecule contains chromium in a +2 oxidation state it is a good reducing agent. For this reason it will reduce the O2 found in air, many other applications exist, including those in the polymer industry. Rice, Steven F. Wilson, Randall B, electronic Absorption Spectrum of Chromous Acetate Dihydrate and Related Binuclear Chromous Carboxylates
29.
Dyeing
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Dyeing is the process of adding color to textile products like fibers, yarns, and fabrics. Dyeing is normally done in a solution containing dyes and particular chemical material. After dyeing, dye molecules have uncut chemical bond with fiber molecules, the temperature and time controlling are two key factors in dyeing. There are mainly two classes of dye, natural and man-made, the primary source of dye, historically, has generally been nature, with the dyes being extracted from animals or plants. Since the mid-19th century, however, humans have produced artificial dyes to achieve a range of colors and to render the dyes more stable to resist washing. Different classes of dyes are used for different types of fiber and at different stages of the production process, from loose fibers through yarn. Acrylic fibers are dyed with basic dyes, while nylon and protein fibers such as wool and silk are dyed with acid dyes, cotton is dyed with a range of dye types, including vat dyes, and modern synthetic reactive and direct dyes. The word dye is from Middle English deie and from Old English dag, the first known use of the word dye was before the 12th century. The earliest dyed flax fibers have found in a prehistoric cave in the Republic of Georgia. In China, dyeing with plants, barks, and insects has been traced more than 5,000 years. Early evidence of dyeing comes from Sindh province in Pakistan, where a piece of cotton dyed with a dye was recovered from the archaeological site at Mohenjo-daro. The dye used in case was madder, which, along with other dyes such as indigo, was introduced to other regions through trade. The first synthetic dye was William Perkins mauveine in 1856, derived from coal tar, alizarin, the red dye present in madder, was the first natural pigment to be duplicated synthetically in 1869, a development which led to the collapse of the market for naturally grown madder. The development of new, strongly colored synthetic dyes followed quickly, dyes are applied to textile goods by dyeing from dye solutions and by printing from dye pastes. Methods include direct application and yarn dyeing and this renders the dye soluble so that it can be absorbed by the fiber since the insoluble dye has very little substantivity to the fiber. Direct dyes, a class of dyes largely for dyeing cotton, are water-soluble, most other classes of synthetic dye, other than vat and surface dyes, are also applied in this way. The term may also be applied to dyeing without the use of mordants to fix the dye once it is applied, mordants were often required to alter the hue and intensity of natural dyes and improve color fastness. Chromium salts were until recently used in dyeing wool with synthetic mordant dyes
30.
Ammonium acetate
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Ammonium acetate, also known as spirit of Mindererus in aqueous solution, is a chemical compound with the formula NH4CH3CO2. It is a white, hygroscopic solid and can be derived from the reaction of ammonia and it is the main precursor to acetamide, NH4CH3CO2 → CH3CNH2 + H2O It is also used as a diuretic. As the salt of an acid and a weak base. Ammonium acetate is volatile at low pressures, because of this, it has been used to replace cell buffers with non-volatile salts in preparing samples for mass spectrometry. It is also popular as a buffer for mobile phases for HPLC with ELSD detection for this reason, other volatile salts that have been used for this include ammonium formate. NH4C2H3O2 is occasionally employed as a biodegradable de-icing agent, ammonium acetate is useful as a catalyst in the Knoevenagel condensation and as a source of ammonia in the Borch reaction in organic synthesis. In dialysis as part of a purification step to remove contaminants via diffusion. In agricultural chemistry used as reagent for determination of soil CEC and determination of potassium in soil. Ammonium acetate is used as a food additive as an acidity regulator. It is approved for usage in Australia and New Zealand, ammonium acetate is produced by the neutralization of acetic acid with ammonium carbonate or by saturating glacial acetic acid with ammonia. Obtaining crystalline ammonium acetate is difficult on account of its aqueous solution giving off ammonia when evaporated
31.
Acetamide
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Acetamide is an organic compound with the formula CH3CONH2. It is the simplest amide derived from acetic acid and it finds some use as a plasticizer and as an industrial solvent. The related compound N, N-dimethylacetamide is more used. This finding is significant because acetamide has an amide bond. This finding lends support to the theory that molecules that can lead to life can form in space. - were seen for the first time on a comet, in addition, acetamide is found infrequently on burning coal dumps, as a mineral of the same name. International Chemical Safety Card 0233 Acetamide
32.
Potassium acetate
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Potassium acetate is the potassium salt of acetic acid. Sesquihydrate in water solution begins to form semihydrate at 41.3 °C, potassium acetate is the salt that forms along with water as acetic acid and potassium hydroxide are neutralized together. Conditions/substances to avoid are, moisture, heat, flames, ignition sources, potassium acetate can be used as a deicer instead of chloride salts such as calcium chloride or magnesium chloride. It offers the advantage of being less aggressive on soils and much less corrosive, potassium acetate is also the extinguishing agent used in class K fire extinguishers because of its ability to cool and form a crust over burning oils. Potassium acetate is used as a food additive as a preservative, in the European Union, it is labeled by the E number E261, it is also approved for usage in the USA and Australia and New Zealand. Potassium hydrogen diacetate with formula KH2 is a food additive with the same E number as potassium acetate. In molecular biology, potassium acetate is used to precipitate dodecyl sulfate and DS-bound proteins and it is also used as a salt for the ethanol precipitation of DNA. Potassium acetate is used in mixtures applied for tissue preservation, fixation, most museums today use the formaldehyde-based method recommended by Kaiserling in 1897 which contains potassium acetate. For example, Lenins mummy was soaked in a bath containing potassium acetate, potassium acetate was incorrectly used in place of potassium chloride when putting a prisoner to death in Oklahoma in January 2015. Potassium acetate is used as a catalyst in the production of polyurethanes, potassium acetate was originally used in the preparation of Cadets fuming liquid, the first organometallic compound produced. It is used as diuretic and urinary alkaliser, and acts by changing the properties of the body fluids
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Polyvinyl alcohol
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Poly is a water-soluble synthetic polymer. It has the formula n. It is used in papermaking, textiles, and a variety of coatings and it is sometimes supplied as beads or as solutions in water. Polyvinyl acetals, Polyvinyl acetals are prepared by reacting aldehydes with polyvinyl alcohol, Polyvinyl butyral and polyvinyl formal are examples of this family of polymers. They are prepared from polyvinyl alcohol by reaction with butyraldehyde and formaldehyde, preparation of polyvinyl butyral is the largest use for polyvinyl alcohol in the U. S. and Western Europe. Polyvinyl alcohol is used as a polymerization aid, as protective colloid. This is the largest market application in China, in Japan its major use is vinylon fiber production. An example is the envelope containing laundry detergent in liqui-tabs, feminine hygiene and adult incontinence products as a biodegradable plastic backing sheet. PVA is widely used in sport fishing. Small bags made from PVA are filled with dry or oil based bait and attached to the hook, or the hook is placed inside the bag. When the bag lands on the lake or river bottom it dissolves in water, leaving the hook bait surrounded by ground bait and this method helps attract fish to the hook bait. Anglers also use string made of PVA for the purpose of making temporary attachments, for example, holding a length of line in a coil, that might otherwise tangle while the cast is made. Unlike most vinyl polymers, PVA is not prepared by polymerization of the corresponding monomer, the monomer, vinyl alcohol, is unstable with respect to acetaldehyde. PVA instead is prepared by first polymerizing vinyl acetate, and the resulting polyvinylacetate is converted to the PVA, other precursor polymers are sometimes used, with formate, chloroacetate groups instead of acetate. Worldwide consumption of alcohol was over one million metric tons in 2006. The North Korean-manufacture fiber Vinalon is produced from polyvinyl alcohol, despite its inferior properties as a clothing fiber, it is produced for self-sufficiency reasons, because no oil is required to produce it. PVA is a material that exhibits crystallinity. In terms of microstructure, it is composed mainly of 1, 3-diol linkages but a few percent of 1, 2-diols occur, Polyvinyl alcohol has excellent film forming, emulsifying and adhesive properties
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Paint
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Paint is any liquid, liquefiable, or mastic composition that, after application to a substrate in a thin layer, converts to a solid film. It is most commonly used to protect, color, or provide texture to objects, Paint can be made or purchased in many colors—and in many different types, such as watercolor, synthetic, etc. Paint is typically stored, sold, and applied as a liquid, in 2001 and 2004, South African archeologists reported finds in Blombos Cave of a 100, 000-year-old human-made ochre-based mixture that could have been used like paint. Further excavation in the cave resulted in the 2011 report of a complete toolkit for grinding pigments. Cave paintings drawn with red or yellow ochre, hematite, manganese oxide, ancient colored walls at Dendera, Egypt, which were exposed for years to the elements, still possess their brilliant color, as vivid as when they were painted about 2,000 years ago. The Egyptians mixed their colors with a substance, and applied them separately from each other without any blending or mixture. They appear to have used six colors, white, black, blue, red, yellow and they first covered the area entirely with white, then traced the design in black, leaving out the lights of the ground color. They used minium for red, and generally of a dark tinge, pliny mentions some painted ceilings in his day in the town of Ardea, which had been done prior to the foundation of Rome. He expresses great surprise and admiration at their freshness, after the lapse of so many centuries, Paint was made with the yolk of eggs and therefore, the substance would harden and adhere to the surface it was applied to. Pigment was made from plants, sand, and different soils, Most paints used either oil or water as a base. The process was done by hand by the painters and exposed them to lead poisoning due to the white-lead powder, in 1718, Marshall Smith invented a Machine or Engine for the Grinding of Colours in England. It is not known precisely how it operated, but it was a device that increased the efficiency of pigment grinding dramatically. By the proper onset of the Industrial Revolution, paint was being ground in steam-powered mills, interior house painting increasingly became the norm as the 19th century progressed, both for decorative reasons and because the paint was effective in preventing the walls rotting from damp. Linseed oil was also used as an inexpensive binder. In 1866, Sherwin-Williams in the United States opened as a large paint-maker and it was not until the stimulus of World War II created a shortage of linseed oil in the supply market that artificial resins, or alkyds, were invented. Cheap and easy to make, they held the color well. The vehicle is composed of the binder, or, if it is necessary to thin the binder with a diluent like solvent or water, it is the combination of binder + diluent. In this case, once the paint has dried or cured very nearly all of the diluent has evaporated, thus, an important quantity in coatings formulation is the vehicle solids, sometimes called the resin solids of the formula
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Cellulose acetate
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Cellulose acetate is the acetate ester of cellulose. It was first prepared in 1865, in photographic film, cellulose acetate replaced nitrate film in the 1950s, being far less flammable and cheaper to produce. In 1865, Paul Schützenberger discovered that cellulose reacts with acetic anhydride to form cellulose acetate, the German chemists Arthur Eichengrün and Theodore Becker invented the first soluble forms of cellulose acetate in 1903. For five years, the Dreyfus brothers studied and experimented in a manner in Switzerland. Unfortunately the outbreak of World War I postponed commercial development of this process, in November 1914, the British Government invited Dr. Camille Dreyfus to come to England to manufacture acetate dope, and the British Cellulose and Chemical Manufacturing Co was set up. In 1917, after the United States had entered the war, War Department invited Dr. Dreyfus to establish a similar factory in the US. Both operations were run throughout the war. After the war, attention returned to the production of acetate fibers, the first yarn was of fair quality, but sales resistance was heavy, and silk associates worked zealously to discredit acetate and discourage its use. However, the nature of acetate made it an excellent fiber for moiré, because the pattern was permanent. The same characteristic also made permanent pleating a commercial fact for the first time, Cellulose acetate and cellulose triacetate are mistakenly referred to as the same fiber, although they are similar, their chemical compositions and formulae differ. Triacetate is known as a description or primary acetate containing no hydroxyl group. Acetate fiber is known as modified or secondary acetate having two or more hydroxyl groups, triacetate fibers, although no longer produced in the United States, contain a higher ratio of acetate-to-cellulose than do acetate fibers. Cellulose acetate film was introduced in 1934 as a replacement for the nitrate film stock that had previously been standard. Acetate film stock is used in some applications, such as camera negative for motion pictures. Since the 1980s, polyester film stock has become more commonplace, Acetate film was also used as the base for magnetic tape, prior to the advent of polyester film. Cellulose acetate magnetic tape was introduced by IBM in 1952 for use on their IBM726 tape drive in the IBM701 computer. It was much lighter and easier to handle than the metal tape introduced by UNIVAC in 1951 for use on their UNISERVO tape drive in the UNIVAC I computer. In 1956 cellulose acetate magnetic tape was replaced by the more stable PET film magnetic tape for use on their IBM727 tape drive, Cellulose acetate fiber is one of the earliest synthetic fibers and is based on cotton or tree pulp cellulose
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Acetate disc
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They are made for special purposes, almost never for sale to the general public. They can be played on any normal record player but will suffer from wear more quickly than vinyl, some acetates are highly prized for their rarity, especially when they contain unpublished material. Acetates are usually made by dubbing from a recording in another medium. Within the vinyl record industry, acetates are used for evaluating the quality of the tape-to-disc transfer. The term acetate derives from the used in examples cut before 1934. Cellulose acetate was only in use for a short while, lower-quality blanks were considered adequate for non-critical uses such as tests and demo discs. One pump usually provides suction for both the turntable and the tube that pulls away the fine string of nitrocellulose lacquer removed by the groove-cutting stylus. Acetates have not always been used solely as a means of evaluating a tape-to-disc transfer or cutting the master disc. They were widely used for many purposes before magnetic tape recorders became common and they were used extensively in Jamaica by sound system operators in the late 1940s and 1950s. Acetates were often used as demos of new recordings by artists, before the introduction of magnetic tape for mastering, disc recording was done live, although sometimes intermediate disc-to-disc editing procedures were involved. Acetate blanks allowed high-quality playable records to be produced instantaneously, acetates were widely used in radio broadcasting to archive live broadcasts, pre-record local programming, and delay network feeds for broadcast at a later time. Sixteen-inch discs recorded at 33⅓ rpm were used for these one-off electrical transcriptions beginning in the mid-1930s, around 1940, disc recorders designed for amateur home use began appearing on the market, but their high prices limited sales and then World War II brought their production to a halt. After the war, the popularity of such recorders greatly increased, countless discs were cut at parties and family gatherings, both for immediate amusement value and to preserve audio snapshots of these events and of the voices of relatives and friends. Acetate discs are less durable than some types of magnetic tape. In preparation for a pressing, acetates are used for quality control prior to the production of the stampers. The actual stampers can be either from normal acetates, or from a DMM disc. In the dance world, DJs cut new or otherwise special tracks on acetates, in order to test crowd response. This practice started as early as in the 1960s in Jamaica and these discs are known as dubplates
. PMID 21209842.
