query: the elements or compounds that go into a chemical reaction are

pos: Chemical reaction are called reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants. Reactions often consist of a sequence of individual sub-steps, the so-called elementary reactions, and the information on the precise course of action is part of the reaction mechanism. Chemical reactions are described with chemical equations, which symbolically present the starting materials, end products, and sometimes intermediate products and reaction conditions. Chemical reactions happen at a characteristic reaction rate at a given temperature and chemical concentration. Typically, reaction rates increase with increasing

neg: Chemical compound of atoms (chemical elements) in a fixed stoichiometric proportion can be termed 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. The ratio of each element in the compound is expressed in a ratio in its chemical formula. A chemical formula is a way of expressing information about the proportions of atoms that constitute a particular chemical compound, using the standard abbreviations

neg: Chemical similarity Chemical similarity Chemical similarity (or molecular similarity) refers to the similarity of chemical elements, molecules or chemical compounds with respect to either structural or functional qualities, i.e. the effect that the chemical compound has on reaction partners in inorganic or biological settings. Biological effects and thus also similarity of effects are usually quantified using the biological activity of a compound. In general terms, function can be related to the chemical activity of compounds (among others). The notion of "chemical similarity" (or "molecular similarity") is one of the most important concepts in chemoinformatics. It plays an important role in modern approaches

neg: Chemical compound compounds, and then bonds are reformed so that new associations are made between atoms. Schematically, this reaction could be described as , where A, B, C, and D are each unique atoms; and AB, AD, CD, and CB are each unique compounds. Chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) composed of atoms from more than one element held together by chemical bonds. A chemical element bonded to an identical chemical element is not a chemical compound since only one element, not two different elements, is involved. There are four types

neg: Chemical change as new products are generated. An example of a chemical change is the reaction between sodium and water to produce sodium hydroxide and hydrogen. So much energy is released that the hydrogen gas released spontaneously burns in the air. This is an example of a chemical change because the end products are chemically different from the substances before the chemical reaction. Chemists categorize chemical changes into three main classes: inorganic chemical changes, organic chemical changes and biochemical changes. Inorganic chemistry describes the reactions of elements and compounds that, in general, do not involve carbon. The changes typically take place in

neg: Chemical state a polar covalent bond. A functional group is very similar to a chemical species and a chemical group. A chemical group or chemical species exhibits a distinctive reaction behavior or a distinctive spectral signal when analyzed by various spectroscopic methods. These three groupings are often used to describe the groups of elements that exist within an organic molecule. The following list of neutral compounds, anions, cations, functional groups and chemical species is a partial list of the many groups of elements that can exhibit or have a unique "chemical state" while being part of the surface or the bulk of

neg: In situ chemical oxidation electrons. One of the reactants in the reaction becomes oxidized, or loses electrons, while the other reactant becomes reduced, or gains electrons. In ISCO, oxidizing compounds, compounds that give electrons away to other compounds in a reaction, are used to change the contaminants into harmless compounds. The "in situ" in ISCO is just Latin for "in place", signifying that ISCO is a chemical oxidation reaction that occurs at the site of the contamination. The remediation of certain organic substances such as chlorinated solvents (trichloroethene and tetrachloroethene), and gasoline-related compounds (benzene, toluene, ethylbenzene, MTBE, and xylenes) by ISCO is possible. Some

neg: Chemical synthesis other meaning of chemical synthesis is narrow and restricted to a specific kind of chemical reaction, a "direct combination reaction", in which two or more reactants combine to form a single product. The general form of a direct combination reaction is: where A and B are elements or compounds, and AB is a compound consisting of A and B. Examples of combination reactions include: 4 special synthesis rules: Chemical synthesis Chemical synthesis is a purposeful execution of chemical reactions to obtain a product, or several products. This happens by physical and chemical manipulations usually involving one or more reactions. In

neg: Chemical substance combined into one substance through a chemical reaction form a chemical compound. All compounds are substances, but not all substances are compounds. A chemical compound can be either atoms bonded together in molecules or crystals in which atoms, molecules or ions form a crystalline lattice. Compounds based primarily on carbon and hydrogen atoms are called organic compounds, and all others are called inorganic compounds. Compounds containing bonds between carbon and a metal are called organometallic compounds. Compounds in which components share electrons are known as covalent compounds. Compounds consisting of oppositely charged ions are known as ionic compounds, or salts.

neg: Polonide iron, molybdenum, tantalum or tungsten. Polonide A polonide is a chemical compound of the radioactive element polonium with any element less electronegative than polonium. Polonides are usually prepared by a direct reaction between the elements at temperatures of around 300–400 °C. They are amongst the most chemically stable compounds of polonium, and can be divided into two broad groups: Some polonides are intermediate between these two cases and others are non-stoichiometric compounds. Alloys containing polonium are also classed as polonides. As polonium is immediately below tellurium in the periodic table, there are many chemical and structural similarities between polonides and

neg: Nucleic acid templated chemistry Nucleic acid templated chemistry Nucleic acid templated chemistry (NATC), or DNA-templated chemistry, is a tool used in the controlled synthesis of chemical compounds. The main advantage of NAT-chemistry (NATC) is that it allows one to perform the chemical reaction as an intramolecular reaction. Two oligonucleotides or their analogues are linked via chemical groups to precursors of chemical compounds. The oligonucleotides recognize specific nucleic acids and are hybridized sterically close to each other. Afterwards the chemical active groups interact with each other to combine the precursors into a completely new chemical compound. NATC is usually used to perform synthesis of complex

neg: Physical change Physical change Physical changes are changes affecting the form of a chemical substance, but not its chemical composition. Physical changes are used to separate mixtures into their component compounds, but can not usually be used to separate compounds into chemical elements or simpler compounds. Physical changes occur when objects or substances undergo a change that does not change their chemical composition. This contrasts with the concept of chemical change in which the composition of a substance changes or one or more substances combine or break up to form new substances. In general a physical change is reversible using physical means.

neg: Traité Élémentaire de Chimie "more appropriately called by the Arabic word alcohol since it is formed from cider or fermented sugar as well as wine", and publishing the first chemical equation "grape must = carbonic acid + alcohol", calling this reaction "one of the most extraordinary in chemistry", noting "In these experiments, we have to assume that there is a true balance or equation between the elements of the compounds with which we start and those obtained at the end of the reaction." The book contains a list of 33 elements, only 23 of which are elements in the modern sense. The elements given

neg: Chemical substance and the International Chemical Identifier or InChI. Often a pure substance needs to be isolated from a mixture, for example from a natural source (where a sample often contains numerous chemical substances) or after a chemical reaction (which often give mixtures of chemical substances). Chemical substance A chemical substance is a form of matter having constant chemical composition and characteristic properties. It cannot be separated into components by physical separation methods, i.e., without breaking chemical bonds. Chemical substances can be simple substances, chemical compounds, or alloys. Chemical elements may or may not be included in the definition, depending on expert

neg: Chemical decomposition is that involving calcium carbonate: Metal chlorates also decompose when heated. In this type of decomposition reaction, a metal chloride and oxygen gas are the products. Here, again, "M" represents the metal: A common decomposition of a chlorate is in the reaction of potassium chlorate where oxygen is the product. This can be written as: Chemical decomposition Chemical decomposition, analysis or breakdown is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds. Chemical decomposition is usually regarded and defined as the exact opposite of chemical synthesis. In short, the chemical reaction

neg: Chemical transport reaction and iodine into the WOI, at the high temperatures near the filament the compound decomposes back to tungsten, oxygen and iodine. Chemical transport reaction In chemistry, a chemical transport reaction describes a process for purification and crystallization of non-volatile solids. The process is also responsible for certain aspects of mineral growth from the effluent of volcanoes. The technique is distinct from chemical vapor deposition, which usually entails decomposition of molecular precursors (e.g. SiH → Si + 2H) and which gives conformal coatings. The technique, which was popularized by Schäfer, entails the reversible conversion of nonvolatile elements and chemical compounds into

neg: Polonide Polonide A polonide is a chemical compound of the radioactive element polonium with any element less electronegative than polonium. Polonides are usually prepared by a direct reaction between the elements at temperatures of around 300–400 °C. They are amongst the most chemically stable compounds of polonium, and can be divided into two broad groups: Some polonides are intermediate between these two cases and others are non-stoichiometric compounds. Alloys containing polonium are also classed as polonides. As polonium is immediately below tellurium in the periodic table, there are many chemical and structural similarities between polonides and tellurides. Lead polonide (PbPo) occurs

neg: Chemical synthesis Chemical synthesis Chemical synthesis is a purposeful execution of chemical reactions to obtain a product, or several products. This happens by physical and chemical manipulations usually involving one or more reactions. In modern laboratory usage, this tends to imply that the process is reproducible, reliable, and established to work in multiple laboratories. A chemical synthesis begins by selection of compounds that are known as reagents or reactants. Various reaction types can be applied to these to synthesize the product, or an intermediate product. This requires mixing the compounds in a reaction vessel such as a chemical reactor or a simple

neg: Chemical transport reaction Chemical transport reaction In chemistry, a chemical transport reaction describes a process for purification and crystallization of non-volatile solids. The process is also responsible for certain aspects of mineral growth from the effluent of volcanoes. The technique is distinct from chemical vapor deposition, which usually entails decomposition of molecular precursors (e.g. SiH → Si + 2H) and which gives conformal coatings. The technique, which was popularized by Schäfer, entails the reversible conversion of nonvolatile elements and chemical compounds into volatile derivatives. The volatile derivative migrates throughout a sealed reactor, typically a sealed and evacuated glass tube heated in a tube

neg: Physical change an alloy can be difficult and may require chemical processing – making an alloy is an example of a physical change that cannot readily be undone by physical means. Alloys where mercury is one of the metals can be separated physically by melting the alloy and boiling the mercury off as a vapour. Physical change Physical changes are changes affecting the form of a chemical substance, but not its chemical composition. Physical changes are used to separate mixtures into their component compounds, but can not usually be used to separate compounds into chemical elements or simpler compounds. Physical changes occur

neg: In situ chemical reduction situ" in ISCR is just Latin for "in place", signifying that ISCR is a chemical reduction reaction that occurs at the site of the contamination. Like ISCO, it is able to decontaminate many compounds, and, in theory, ISCR could be more effective in ground water remediation than ISCO. Chemical reduction is one half of a redox reaction, which results in the gain of electrons. One of the reactants in the reaction becomes oxidized, or loses electrons, while the other reactant becomes reduced, or gains electrons. In ISCR, reducing compounds, compounds that accept electrons given by other compounds in a reaction,

neg: Concise Dictionary of Spoken Chinese "are treated as morphemes, or monosyllabic meaningful spoken words", whether bound morphemes or free morphemes, rather than as characters. Chao gives a chemical analogy to differentiate between "zìdiǎn" 字典 "character dictionaries" and "cídiǎn" 辭典 "word dictionaries". In China, dictionaries are divided into 字典 and 詞典, the former giving only single characters, which may be compared with chemical elements, and the latter compounds and phrases, like chemical compounds. To pursue the chemical analogy one step further, compounds are so numerous that they cannot all be included except in a much more comprehensive work. We can do more than merely list the

neg: Organic redox reaction reaction forming two separate compounds. Asymmetric catalytic reductions and asymmetric catalytic oxidations are important in asymmetric synthesis. Most oxidations are conducted with air or oxygen. These oxidation include routes to chemical compounds, remediation of pollutants, and combustion. Several reaction mechanisms exist for organic oxidations: Several reaction mechanisms exist for organic reductions: Reductions that do not fit in any reduction reaction mechanism and in which just the change in oxidation state is reflected include the Wolff-Kishner reaction. Organic redox reaction Organic reductions or organic oxidations or organic redox reactions are redox reactions that take place with organic compounds. In organic chemistry

neg: Chemical decomposition Chemical decomposition Chemical decomposition, analysis or breakdown is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds. Chemical decomposition is usually regarded and defined as the exact opposite of chemical synthesis. In short, the chemical reaction in which two or more products are formed from a single reactant is called a decomposition reaction. The details of a decomposition process are not always well defined but some of the process is understood; much energy is needed to break bonds. Since all decomposition reactions break apart the bonds holding it together in order

neg: Binary compounds of silicon Binary compounds of silicon Binary compounds of silicon are binary chemical compounds containing silicon and one other chemical element. Technically the term silicide is reserved for any compounds containing silicon bonded to a more electropositive element. Binary silicon compounds can be grouped into several classes. Saltlike silicides are formed with the electropositive s-block metals. Covalent silicides and silicon compounds occur with hydrogen and the elements in groups 10 to 17. Transition metals form metallic silicides with some exceptions: silver, gold and the group 12 elements. The general composition is MSi or MSi with n ranging from 1 to 6. Examples

neg: Organogallium chemistry Organogallium chemistry Organogallium chemistry is the chemistry of organometallic compounds containing a carbon to gallium (Ga) chemical bond. Despite their high toxicity , organogallium compounds have some use in organic synthesis. The compound trimethylgallium is of some relevance to MOCVD as a precursor to gallium arsenide via its reaction with arsine at 700 °C: Gallium trichloride is an important reagent for the introduction of gallium into organic compounds. The main gallium oxidation state is Ga(III), as in all lower group 13 elements (such as aluminium). Compounds of the type RGa are monomeric. Lewis acidity decreases in the order Al >

neg: Roman candle (firework) as an oxidizer, chemical reactions involving the dissociated elements of the perchlorate—potassium and chlorine ions—create barium compounds which emit green light (especially BaCl). The potassium compounds formed by this reaction emit mostly near-infrared light, and so they do not affect the color of the star in a significant way. This reaction occurs at temperatures exceeding 2500 °C (4500 °F), at which the ions in KCl dissociate into free K and Cl. Alternatively, SrCO can be added to the candle to produce a red or pink star, but, because it does not oxidize, more oxidizers and fuels must be added to

neg: Organic compound not generally considered to be chemical "compounds". For many centuries, Western physicians and chemists believed in vitalism. This was the widespread conception that substances found in organic nature are created from the chemical elements by the action of a "vital force" or "life-force" ("vis vitalis") that only living organisms possess. Vitalism taught that these "organic" compounds were fundamentally different from the "inorganic" compounds that could be obtained from the elements by chemical manipulations. Vitalism survived for a while even after the rise of modern ideas about the atomic theory and chemical elements. It first came under question in 1824, when

neg: Chemical compound from chemical compounds, which require 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 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

neg: Bacteria correspond with modern genetic classifications. Bacterial metabolism is classified into nutritional groups on the basis of three major criteria: the source of energy, the electron donors used, and the source of carbon used for growth. Bacteria either derive energy from light using photosynthesis (called phototrophy), or by breaking down chemical compounds using oxidation (called chemotrophy). Chemotrophs use chemical compounds as a source of energy by transferring electrons from a given electron donor to a terminal electron acceptor in a redox reaction. This reaction releases energy that can be used to drive metabolism. Chemotrophs are further divided by the types of

neg: Reagent are not useful tool compounds, and are classified by medicinal chemists as "pan-assay interference compounds". Reagent A reagent is a substance or compound added to a system to cause a chemical reaction, or added to test if a reaction occurs. The terms "reactant" and "reagent" are often used interchangeably—however, a reactant is more specifically a substance "consumed" in the course of a chemical reaction. "Solvents", though involved in the reaction, are usually not called reactants. Similarly, "catalysts" are not consumed by the reaction, so they are not reactants. In biochemistry, especially in connection with enzyme-catalyzed reactions, the reactants are commonly

neg: Chemical affinity mixture of chemical species with the possibility of chemical reaction, it can be proven that the following relation holds: With the writings of Théophile de Donder as precedent, Ilya Prigogine and Defay in "Chemical Thermodynamics" (1954) defined chemical affinity as the rate of change of the uncompensated heat of reaction "Q"' as the reaction progress variable or reaction extent "ξ" grows infinitesimally: Chemical affinity In chemical physics and physical chemistry, chemical affinity is the electronic property by which dissimilar chemical species are capable of forming chemical compounds. Chemical affinity can also refer to the tendency of an atom or compound

neg: Mineral (nutrient) hormones. In the figure, minerals are color highlighted in purple. Dietitians may recommend that minerals are best supplied by ingesting specific foods rich with the chemical element(s) of interest. The elements may be naturally present in the food (e.g., calcium in dairy milk) or added to the food (e.g., orange juice fortified with calcium; iodized salt fortified with iodine). Dietary supplements can be formulated to contain several different chemical elements (as compounds), a combination of vitamins and/or other chemical compounds, or a single element (as a compound or mixture of compounds), such as calcium (calcium carbonate, calcium citrate) or magnesium

neg: Atom display multiple valences, or tendencies to share differing numbers of electrons in different compounds. Thus, chemical bonding between these elements takes many forms of electron-sharing that are more than simple electron transfers. Examples include the element carbon and the organic compounds. The chemical elements are often displayed in a periodic table that is laid out to display recurring chemical properties, and elements with the same number of valence electrons form a group that is aligned in the same column of the table. (The horizontal rows correspond to the filling of a quantum shell of electrons.) The elements at the far

neg: Multi-component reaction reaction with the Asinger reaction. MCR's are an important tool in new drug discovery. MCR's can often be extended into combinatorial, solid phase or flow syntheses for developing new lead structures of active agents. Multi-component reaction In chemistry, a multi-component reaction (or MCR), sometimes referred to as a "Multi-component Assembly Process" (or MCAP), is a chemical reaction where three or more compounds react to form a single product. By definition, multicomponent reactions are those reactions whereby more than two reactants combine in a sequential manner to give highly selective products that retain majority of the atoms of the starting material.

neg: Chemical substance the mild pain-killer Naproxen is the more common name for the chemical compound (S)-6-methoxy-α-methyl-2-naphthaleneacetic acid. Chemists frequently refer to chemical compounds using chemical formulae or molecular structure of the compound. There has been a phenomenal growth in the number of chemical compounds being synthesized (or isolated), and then reported in the scientific literature by professional chemists around the world. An enormous number of chemical compounds are possible through the chemical combination of the known chemical elements. As of May 2011, about sixty million chemical compounds are known. The names of many of these compounds are often nontrivial and hence not

neg: Chemistry elements (helium, neon, argon, krypton, xenon and radon) are composed of lone atoms as their smallest discrete unit, but the other isolated chemical elements consist of either molecules or networks of atoms bonded to each other in some way. Identifiable molecules compose familiar substances such as water, air, and many organic compounds like alcohol, sugar, gasoline, and the various pharmaceuticals. However, not all substances or chemical compounds consist of discrete molecules, and indeed most of the solid substances that make up the solid crust, mantle, and core of the Earth are chemical compounds without molecules. These other types of substances,

neg: Chemical compound 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 the two or more atom requirement, though they often consist of molecules composed of multiple atoms (such as in the diatomic molecule H, or the polyatomic molecule S, 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,

neg: Chemical oscillator Chemical oscillator A chemical oscillator is a complex mixture of reacting chemical compounds in which the concentration of one or more components exhibits periodic changes, They are a class of reactions that serve as an example of non-equilibrium thermodynamics with far-from-equilibrium behavior. The reactions are theoretically important in that they show that chemical reactions do not have to be dominated by equilibrium thermodynamic behavior. In cases where one of the reagents has a visible color, periodic color changes can be observed. Examples of oscillating reactions are the Belousov-Zhabotinsky reaction (BZ), the Briggs-Rauscher reaction, the Bray-Liebhafsky reaction and the chlorine dioxide

neg: Chemical element chemical bonds, they form chemical compounds. Only a minority of elements are found uncombined as relatively pure minerals. Among the more common of such native elements are copper, silver, gold, carbon (as coal, graphite, or diamonds), and sulfur. All but a few of the most inert elements, such as noble gases and noble metals, are usually found on Earth in chemically combined form, as chemical compounds. While about 32 of the chemical elements occur on Earth in native uncombined forms, most of these occur as mixtures. For example, atmospheric air is primarily a mixture of nitrogen, oxygen, and argon, and

neg: Substitution reaction radical substitution reaction involves radicals. An example is the Hunsdiecker reaction. Coupling reactions are a class of metal-catalyzed reactions involving an organometallic compound RM and an organic halide R'X that together react to form a compound of the type R-R' with formation of a new carbon-carbon bond. Examples include the Heck reaction, Ullmann reaction, and Wurtz–Fittig reaction. Many variations exist. Substituted compounds are chemical compounds where one or more hydrogen atoms of a core structure have been replaced with a functional group like alkyl, hydroxy, or halogen, or with larger substituent groups. For example, benzene is a simple aromatic ring.

neg: Metalorganic vapour-phase epitaxy alloys, and it has become a major process in the manufacture of optoelectronics. It was invented in 1968 by Harold M. Manasevit. In MOCVD ultrapure gases are injected into a reactor and finely dosed to deposit a very thin layer of atoms onto a semiconductor wafer. Surface reaction of organic compounds or metalorganics and hydrides containing the required chemical elements creates conditions for crystalline growth – epitaxy of materials and compound semiconductors. Unlike traditional silicon semiconductors, these semiconductors may contain combinations of group III and group V, group II and group VI, group IV, or group IV, V and VI

neg: Applications of 3D printing to make specialized, bespoke geometries. In 2012 a proof of principle project at the University of Glasgow, UK, showed that it is possible to use 3D printing techniques to assist in the production of chemical compounds. They first printed chemical reaction vessels, then used the printer to deposit reactants into them. They have produced new compounds to verify the validity of the process, but have not pursued anything with a particular application. Usually, the FDM process is used to print hollow reaction vessels or microreactors. If the 3D print is performed within an inert gas atmosphere, the reaction vessels can

neg: Ore resources on Mars the ground is called magma. When magma sits in underground chambers, slowly cooling over thousands of years, heavier elements sink. These elements, including copper, chromium, iron, and nickel become concentrated at the bottom. When magma is hot, many elements are free to move. As cooling proceeds, the elements bind with each other to form chemical compounds or minerals. Because some elements do not bond easily to form minerals, they exist freely after nearly all the other elements have bonded into compounds or minerals. The remaining elements are called incompatible elements. Some of them are quite useful to humans. Some examples

neg: Color reaction Color reaction In chemistry, a color reaction or colour reaction is a chemical reaction that is used to transform colorless chemical compounds into colored derivatives which can be detected visually or with the aid of a colorimeter. The concentration of a colorless solution cannot normally be determined with a colorimeter. The addition of a color reagent leads to a color reaction and the absorbance of the colored product can then be measured with a colorimeter. A change in absorbance in the ultraviolet range cannot be detected by eye but can be measured by a suitably equipped colorimeter. A special colorimeter

neg: Volatiles Volatiles In planetary science, volatiles are the group of chemical elements and chemical compounds with low boiling points that are associated with a planet's or moon's crust or atmosphere. Examples include nitrogen, water, carbon dioxide, ammonia, hydrogen, methane and sulfur dioxide. In astrogeology, these compounds, in their solid state, often comprise large proportions of the crusts of moons and dwarf planets. In contrast with volatiles, elements and compounds with high boiling points are known as "refractory substances". Planetary scientists often classify volatiles with exceptionally low melting points, such as hydrogen and helium, as gases (as in gas giant), whereas those

neg: Chemical compound indicate the number of atoms involved. For example, water is composed of two hydrogen atoms bonded to one oxygen atom: the chemical formula is HO. Many chemical compounds have a unique numerical identifier assigned by the Chemical Abstracts Service (CAS): its CAS number. A compound can be converted to 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. Any substance consisting of two or more different types

neg: Explosive safer to handle; aluminium powder may be introduced to increase total energy and blast effects. Explosive compounds are also often "alloyed": HMX or RDX powders may be mixed (typically by melt-casting) with TNT to form Octol or Cyclotol. An oxidizer is a pure substance (molecule) that in a chemical reaction can contribute some atoms of one or more oxidizing elements, in which the fuel component of the explosive burns. On the simplest level, the oxidizer may itself be an oxidizing element, such as gaseous or liquid oxygen. The availability and cost of explosives are determined by the availability of the

neg: In situ chemical oxidation found at the following sites: In situ chemical oxidation In situ chemical oxidation (ISCO), a form of advanced oxidation processes and advanced oxidation technology, is an environmental remediation technique used for soil and/or groundwater remediation to reduce the concentrations of targeted environmental contaminants to acceptable levels. ISCO is accomplished by injecting or otherwise introducing strong chemical oxidizers directly into the contaminated medium (soil or groundwater) to destroy chemical contaminants in place. It can be used to remediate a variety of organic compounds, including some that are resistant to natural degradation. Chemical oxidation is one half of a redox reaction, which

neg: In situ chemical oxidation In situ chemical oxidation In situ chemical oxidation (ISCO), a form of advanced oxidation processes and advanced oxidation technology, is an environmental remediation technique used for soil and/or groundwater remediation to reduce the concentrations of targeted environmental contaminants to acceptable levels. ISCO is accomplished by injecting or otherwise introducing strong chemical oxidizers directly into the contaminated medium (soil or groundwater) to destroy chemical contaminants in place. It can be used to remediate a variety of organic compounds, including some that are resistant to natural degradation. Chemical oxidation is one half of a redox reaction, which results in the loss of

neg: Polonium hydride Polonium hydride Polonium hydride (also known as polonium dihydride, hydrogen polonide, or polane) is a chemical compound with the formula PoH. It is a liquid at room temperature, the second hydrogen chalcogenide with this property after water. It is very unstable chemically and tends to decompose into elemental polonium and hydrogen; like all polonium compounds, it is highly radioactive. It is a volatile and very labile compound, from which many polonides can be derived. Polonium hydride cannot be produced by direct reaction from the elements upon heating. Other unsuccessful routes to synthesis include the reaction of polonium tetrachloride (PoCl) with

neg: Chemical compound 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 HO. 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 (0.02 < x < 0.58)]. Chemical compounds have 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

neg: Biosynthesis inefficiencies. Biosynthesis Biosynthesis (also called anabolism) 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, or joined together to form macromolecules. This process often consists of metabolic pathways. Some of these biosynthetic pathways are located within a single cellular organelle, while others involve enzymes that are located within multiple cellular organelles. Examples of these biosynthetic pathways include the production of lipid membrane components and nucleotides. The prerequisite elements for biosynthesis include: precursor compounds, chemical energy (e.g. ATP), and catalytic enzymes which may require

neg: Biosynthesis Biosynthesis Biosynthesis (also called anabolism) 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, or joined together to form macromolecules. This process often consists of metabolic pathways. Some of these biosynthetic pathways are located within a single cellular organelle, while others involve enzymes that are located within multiple cellular organelles. Examples of these biosynthetic pathways include the production of lipid membrane components and nucleotides. The prerequisite elements for biosynthesis include: precursor compounds, chemical energy (e.g. ATP), and catalytic enzymes which may require coenzymes

neg: Electrochemical cell reaction where electrons are lost is called a oxidation reaction A reaction where both reduction and oxidation occur is called a redox reaction. A redox reaction occurs when electrons are transferred from a substance that is oxidized to one that is being reduced. An electrolytic cell is an electrochemical cell that drives a non-spontaneous redox reaction through the application of electrical energy. They are often used to decompose chemical compounds, in a process called electrolysis—the Greek word lysis means "to break up". Important examples of electrolysis are the decomposition of water into hydrogen and oxygen, and bauxite into aluminium and

neg: Polymerization Polymerization In polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many forms of polymerization and different systems exist to categorize them. In chemical compounds, polymerization occurs via a variety of reaction mechanisms that vary in complexity due to functional groups present in reacting compounds and their inherent steric effects. In more straightforward polymerization, alkenes form polymers through relatively simple radical reactions; in contrast, more complex reactions such as those that involve substitution at the carbonyl group require more complex synthesis due to the way

neg: Inverse electron-demand Diels–Alder reaction Inverse electron-demand Diels–Alder reaction The Inverse electron demand Diels–Alder reaction, or DA or IEDDA is an organic chemical reaction, in which two new chemical bonds and a six-membered ring are formed. It is related to the Diels–Alder reaction, but unlike the Diels–Alder (or DA) reaction, the DA is a cycloaddition between an electron-rich dienophile and an electron-poor diene. During a DA reaction, three pi-bonds are broken, and two sigma bonds and one new pi-bond are formed. A prototypical DA reaction is shown on the right. DA reactions often involve heteroatoms, and can be used to form heterocyclic compounds. This makes

neg: Organoscandium chemistry by reaction of ScCl with allylpotassium in THF. In Sc(CH)(THF) two allyl ligands are η coordinated and one allyl ligand is η coordinated. Organoscandium chemistry Organoscandium chemistry is the chemistry of organometallic compounds containing a carbon to scandium chemical bond. The interest in organoscandium compounds is mostly academic but several compound classes find practical application in catalysis, especially in polymerization. A common precursor is scandium chloride. As with the other elements in group 3 – e.g. yttrium, forming organoyttrium compounds – and the lanthanides, the dominant oxidation state for scandium in organometallic compounds is +3 (electron configuration [Ar] 3d4s). The

neg: Chemical reaction Chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur. The substance (or substances) initially involved in a chemical reaction

neg: Reduction of nitro compounds Reduction of nitro compounds The chemical reactions described as reduction of nitro compounds can be affected by many reagents and reaction conditions. Historically, the nitro group was one of the first functional groups to be reduced. Alkyl and aryl nitro compounds behave differently. Thus, reduction conditions can be broadly classified by starting materials: aliphatic nitro compounds or aromatic nitro compounds. Secondary classifications are based upon reaction products. "Hydrodenitration" (replacement of a nitro group with hydrogen) is difficult to achieve but can be effected by catalytic hydrogenation over platinum on silica gel at high temperatures. The reaction can also be done

neg: Three-age system of layers (or as close to it as possible) with different sections attested in different regions. Ideally once the layer of the artifact or event is known a quick lookup of the layer in the grand system will provide a ready date. This is considered the most reliable method. It is used for calibration of the less reliable chemical methods. Any material sample contains elements and compounds that are subject to decay into other elements and compounds. In cases where the rate of decay is predictable and the proportions of initial and end products can be known exactly, consistent dates

neg: Chemical affinity Chemical affinity In chemical physics and physical chemistry, chemical affinity is the electronic property by which dissimilar chemical species are capable of forming chemical compounds. Chemical affinity can also refer to the tendency of an atom or compound to combine by chemical reaction with atoms or compounds of unlike composition. The idea of "affinity" is extremely old. Many attempts have been made at identifying its origins. The majority of such attempts, however, except in a general manner, end in futility since "affinities" lie at the basis of all magic, thereby pre-dating science. Physical chemistry, however, was one of the first

neg: Inverse electron-demand Diels–Alder reaction the solubility, polychlorination also turned out to improve substantially the stability of these compounds towards photooxidation, which has been known to be another serious drawback of tetranaphthoporphyrins. Inverse electron-demand Diels–Alder reaction The Inverse electron demand Diels–Alder reaction, or DA or IEDDA is an organic chemical reaction, in which two new chemical bonds and a six-membered ring are formed. It is related to the Diels–Alder reaction, but unlike the Diels–Alder (or DA) reaction, the DA is a cycloaddition between an electron-rich dienophile and an electron-poor diene. During a DA reaction, three pi-bonds are broken, and two sigma bonds and one new

neg: Binary compounds of silicon Other known stable fluorides in this group are SiF, SiF (liquid) and polymeric solids known as polysilicon fluorides (SiF) and (SiF). The other halides form similar binary silicon compounds. > Binary compounds of silicon Binary compounds of silicon are binary chemical compounds containing silicon and one other chemical element. Technically the term silicide is reserved for any compounds containing silicon bonded to a more electropositive element. Binary silicon compounds can be grouped into several classes. Saltlike silicides are formed with the electropositive s-block metals. Covalent silicides and silicon compounds occur with hydrogen and the elements in groups 10 to 17.

neg: Smelting elements, such as oxygen (as an oxide), sulfur (as a sulfide), or carbon and oxygen together (as a carbonate). To extract the metal, workers must make these compounds undergo a chemical reaction. Smelting therefore consists of using suitable reducing substances that combine with those oxidizing elements to free the metal. In the case of carbonates and sulfides, a process called "roasting" drives out the unwanted carbon or sulfur, leaving an oxide, which can be directly reduced. Roasting is usually carried out in an oxidizing environment. A few practical examples: Reduction is the final, high-temperature step in smelting, in which the

neg: Reactive intermediate on carbon are radicals, carbenes, carbocations, carbanions, arynes, and carbynes. Reactive intermediates have several features in common: Reactive intermediate In chemistry, a reactive intermediate or an intermediate is a short-lived, high-energy, highly reactive molecule. When generated in a chemical reaction, it will quickly convert into a more stable molecule. Only in exceptional cases can these compounds be isolated and stored, e.g. low temperatures, matrix isolation. When their existence is indicated, reactive intermediates can help explain how a chemical reaction takes place. Most chemical reactions take more than one elementary step to complete, and a reactive intermediate is a high-energy, yet

neg: Chemical affinity with other kinds diagrams. Joseph Black, for example, used the table in combination with chiastic and circlet diagrams to visualise the core principles of chemical affinity. Affinity tables were used throughout Europe until the early 19th century when they were displaced by affinity concepts introduced by Claude Berthollet. In chemical physics and physical chemistry, chemical affinity is the electronic property by which dissimilar chemical species are capable of forming chemical compounds. Chemical affinity can also refer to the tendency of an atom or compound to combine by chemical reaction with atoms or compounds of unlike composition. In modern terms, we

neg: Chemical substance Chemical substance A chemical substance is a form of matter having constant chemical composition and characteristic properties. It cannot be separated into components by physical separation methods, i.e., without breaking chemical bonds. Chemical substances can be simple substances, chemical compounds, or alloys. Chemical elements may or may not be included in the definition, depending on expert viewpoint. Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure water; it has the same properties and the same ratio of hydrogen to oxygen whether it is isolated from a river or

neg: Chemical compound Chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) composed of atoms from more than one element held together by chemical bonds. A chemical element bonded to an identical chemical element is not a chemical compound since only one element, not two different elements, is involved. There are four types of compounds, depending on how the constituent atoms are held together: A chemical formula is a way of expressing information about the proportions of atoms that constitute a particular chemical compound, using the standard abbreviations for the chemical elements, and subscripts to

neg: Compounds of carbon zinc, and zirconium. For example, many of these metals are smelted with coke, a form of carbon; and aluminum and magnesium are made in electrolytic cells with carbon electrodes. Some distribution of carbon into all of these metals is inevitable. Compounds of carbon Compounds of carbon are defined as chemical substances containing carbon. More compounds of carbon exist than any other chemical element except for hydrogen. Organic carbon compounds are far more numerous than inorganic carbon compounds. In general bonds of carbon with other elements are covalent bonds. Carbon is tetravalent but carbon free radicals and carbenes occur as short-lived

neg: Chemical element These are often a single capital letter, and the letters are reserved and not used for names of specific elements. For example, an "X" indicates a variable group (usually a halogen) in a class of compounds, while "R" is a radical, meaning a compound structure such as a hydrocarbon chain. The letter "Q" is reserved for "heat" in a chemical reaction. "Y" is also often used as a general chemical symbol, although it is also the symbol of yttrium. "Z" is also frequently used as a general variable group. "E" is used in organic chemistry to denote an electron-withdrawing group

neg: Ugi reaction synthesize a great number of different compounds in one reaction, by the reaction of various ketones (or aldehydes), amines, isocyanides and carboxylic acids. These libraries can then be tested with enzymes or living organisms to find new active pharmaceutical substances. One drawback is the lack of chemical diversity of the products. Using the Ugi reaction in combination with other reactions enlarges the chemical diversity of possible products. Examples of Ugi reaction combinations: Crixivan can be prepared using the Ugi reaction. Additionally, many of the "caine"-type anesthetics are synthesized using this reaction. Examples include lidocaine and bupivacaine. Ugi reaction The Ugi

neg: Fusion welding oxygen as a primary ignition source in tandem with another gas such as acetylene to produce a flame which is 2500C at the tip and 2800-3500C at the tip of the inner cone. Other gasses such as propane and methanol can be used for oxyfuel welding. Acetylene is the most common gas used in oxyfuel welding. Solid reactant welding uses reactions between elements and compounds. Certain compounds when mixed create an exothermic chemical reaction, meaning they give off heat. A very common reaction uses thermite, a combination of a metal oxide (rust) and aluminum. This reaction produces heat over 4000F.

neg: Organovanadium chemistry can also be a ligand: and benzene: Many η alkyl and aryl complexes exist for example with mesitylene groups: or norbornyl groups: Vanadium oxytrichloride is a starting material for vanadium(V) compounds: Vanadium compounds appear as catalysts and reagents in several specific reactions. Two main reactions are coupling reactions: and insertion reaction into the C-V bond for example in a sequence forming acetone: Organovanadium chemistry Organovanadium chemistry is the chemistry of organometallic compounds containing a carbon to vanadium (V) chemical bond. Organovanadium compounds are of some relevance to organic synthesis and to polymer chemistry as reagents and catalysts. Oxidation states for

neg: Chemical process Chemical process In a scientific sense, a chemical process is a method or means of somehow changing one or more chemicals or chemical compounds. Such a chemical process can occur by itself or be caused by an outside force, and involves a chemical reaction of some sort. In an "engineering" sense, a chemical process is a method intended to be used in manufacturing or on an industrial scale (see Industrial process) to change the composition of chemical(s) or material(s), usually using technology similar or related to that used in chemical plants or the chemical industry. Neither of these definitions are

neg: Hydrocarbon ingestion of these cytotoxic chemical compounds. Intravenous or subcutaneous injection of petroleum compounds with intent of suicide or abuse is an extraordinary event that can result in local damage or systemic toxicity such as tissue necrosis, abscess formation, respiratory system failure and partial damage to the kidneys, the brain and the nervous system. Moaddab and Eskandarlou report a case of chest wall necrosis and empyema resulting from attempting suicide by injection of petroleum into the pleural cavity. There are three main types of reactions: Substitution reactions only occur in saturated hydrocarbons (single carbon–carbon bonds). In this reaction, an alkane reacts

neg: COSILAB COSILAB COSILAB is a software tool for solving complex chemical kinetics problems. It is used worldwide in research and industry, in particular in automotive, combustion, and chemical processing applications. Problems to be solved by COSILAB may involve thousands of reactions amongst hundreds of species for practically any mixture composition, pressure and temperature. Its computational capabilities allow for a complex chemical reaction to be studied in detail, including intermediate compounds, trace compounds and pollutants. Whilst complex chemistry is accounted for, chemical reactor or combustion geometries that can be handled by COSILAB are relatively simple. For the purpose of ``real-life" simulations this

neg: Alkali metal and polytellurides are formed along with the selenides and tellurides with the and ions. They may be obtained directly from the elements in liquid ammonia or when air is not present, and are colourless, water-soluble compounds that air oxidises quickly back to selenium or tellurium. The alkali metal polonides are all ionic compounds containing the Po ion; they are very chemically stable and can be produced by direct reaction of the elements at around 300–400 °C. The alkali metals are among the most electropositive elements on the periodic table and thus tend to bond ionically to the most electronegative elements

neg: Richard Catlow Richard has made considerable contributions to areas as diverse as catalysis and mineralogy. His approach has also advanced our understanding of how defects — missing or extra atoms — in the structure of solids can result in non-stoichiometric compounds. Such compounds have special electrical or chemical properties since their contributing elements are present in slightly different proportions to those predicted by chemical formula. Catlow’s work has offered insight into mechanisms of industrial catalysts, especially involving microporous materials and metal oxides. In structural chemistry and mineralogy. Simulation methods are now routinely used to predict the structures of complex solids and silicates,

neg: Metabolite include antibiotics and pigments such as resins and terpenes etc. Some antibiotics use primary metabolites as precursors, such as actinomycin which is created from the primary metabolite, tryptophan. Some sugars are metabolites, such as fructose or glucose, which are both present in the metabolic pathways. Examples of primary metabolites produced by industrial microbiology: The metabolome forms a large network of metabolic reactions, where outputs from one enzymatic chemical reaction are inputs to other chemical reactions. Metabolites from chemical compounds, whether inherent or pharmaceutical, are formed as part of the natural biochemical process of degrading and eliminating the compounds. The rate

neg: Homologation reaction Homologation reaction A homologation reaction, also known as homologization, is any chemical reaction that converts the reactant into the next member of the homologous series. A homologous series is a group of compounds that differ by a constant unit, generally a (-CH-) group. The reactants undergo a homologation when the number of a repeated structural unit in the molecules is increased. The most common homologation reactions increase the number of methylene (-CH-) units in saturated chain within the molecule. For example, the reaction of aldehydes or ketones with diazomethane or methoxymethylenetriphenylphosphine to give the next homologue in the series. Examples

neg: Skeletal formula but represent certain very common substituents or indicate an unspecified member of a group of elements. These are known as pseudoelement symbols or organic elements and are treated like univalent "elements" in skeletal formulae. A list of pseudoelement symbols in common use is shown below: Sulfonate esters are often leaving groups in nucleophilic substitution reactions. "See the articles on sulfonyl and sulfonate groups for further information." A protecting group or protective group is introduced into a molecule by chemical modification of a functional group to obtain chemoselectivity in a subsequent chemical reaction, facilitating multistep organic synthesis. Two atoms can be

neg: Chemistry its elements. The standard nomenclature of compounds is set by the International Union of Pure and Applied Chemistry (IUPAC). Organic compounds are named according to the organic nomenclature system. The names for inorganic compounds are created according to the inorganic nomenclature system. When a compound has more than one component, then they are divided into two classes, the electropositive and the electronegative components. In addition the Chemical Abstracts Service has devised a method to index chemical substances. In this scheme each chemical substance is identifiable by a number known as its CAS registry number. A "molecule" is the smallest indivisible

neg: Oxophilicity hexachloride and butyl lithium is useful for the deoxygenation of epoxides. Such conversions are sometimes valuable in organic synthesis. In the McMurry reaction, ketones are converted into alkenes using oxophilic reagents: Similarly, Tebbe's reagent is used in olefination reactions: Oxophilic main group compounds are also well known and useful. The highly oxophilic reagent SiCl stereospecifically deoxygenates phosphine oxides. Phosphorus pentasulfide and the related Lawesson's reagent convert certain organic carbonyls to the corresponding sulfur derivatives: Oxophilicity Oxophilicity is the tendency of certain chemical compounds to form oxides by hydrolysis or abstraction of oxygen, often from organic compounds. The term is usually

neg: Aluminium sulfide Molecular derivatives of AlS are not known. Mixed Al-S-Cl compounds are however known. AlSe and AlTe are also known. Aluminium sulfide is readily prepared by ignition of the elements This reaction is extremely exothermic and it is not necessary or desirable to heat the whole mass of the sulfur-aluminium mixture; (except possibly for very small amounts of reactants). The product will be created in a fused form; it reaches a temperature greater than 1100 °C and may melt its way through steel. The cooled product is very hard. Aluminium sulfide Aluminum sulfide or aluminium sulphide is a chemical compound with

neg: Stanley Miller the reaction tube (or was so chided by his classmates). This was not the case and the result was a clear demonstration that a host of "organic" chemical compounds could be produced by purely inorganic processes. Miller eventually earned his doctorate degree in 1954, and a long-lasting reputation. From spectroscopic observations on stars, it is now well known that complex organic compounds are formed in the gases blown off of carbon rich stars as a result of chemical reactions. The fundamental issue of what the connection was between the "pre-biotic organic" compounds and the origin of life has remained. After

neg: Chemical state Such a compound or salt is described as an ionic compound with ionic bonds which means that, in effect, all of the electron density of one or more valence electrons has been transferred from the less electronegative group of elements to the more electronegative group of elements. In the case of a non-ionic compound the chemical bonds are non-ionic such meaning the compound will probably not dissolve in water or another polar solvent. Many non-ionic compounds have chemical bonds that share the electron density that binds them together. This type of chemical bond is either a non-polar covalent bond or

neg: Component (thermodynamics) molar quantities). Suppose that a chemical system has elements and chemical species (elements or compounds). The latter are combinations of the former, and each species can be represented as a sum of elements: where is the symbol for element and are the components of an matrix. Each species is determined by a vector (a row of this matrix), but the rows are not necessarily linearly independent. If the rank of the matrix is , then there are linearly independent vectors, and the remaining vectors can be obtained by adding up multiples of those vectors. The chemical species represented by those

neg: Inner sphere electron transfer blue. Many solids are mixed-valency including indium chalcogenides. Mixed valency is required for organic metals to exhibit electrical conductivity. As the extinction coefficient decreases, the coupling constant decreases, influencing the angle to increase. Mixed-valence compounds are subdivided into three groups, according to the Robin-Day Classification: Organic mixed valence compounds are also known. Inner sphere electron transfer Inner sphere or bonded electron transfer is a redox chemical reaction that proceeds via a covalent linkage—a strong electronic interaction—between the oxidant and the reductant reactants. In Inner Sphere (IS) electron transfer (ET), a ligand bridges the two metal redox centers during the electron

neg: Water-fuelled car energy required to facilitate such production, would therefore violate the first or second law of thermodynamics. A water-fuelled car is not any of the following: According to the currently accepted laws of physics, there is no way to extract chemical energy from water alone. Water itself is highly stable—it was one of the classical elements and contains very strong chemical bonds. Its enthalpy of formation is negative (-68.3 kcal/mol or -285.8 kJ/mol), meaning that energy is required to break those stable bonds, to separate water into its elements, and there are no other compounds of hydrogen and oxygen with more

neg: Salt (chemistry) are formed by a chemical reaction between: Strong salts or strong electrolyte salts are chemical salts composed of strong electrolytes. These ionic compounds dissociate completely in water. They are generally odourless and nonvolatile. Strong salts start with Na__, K__, NH__, or they end with __NO, __ClO, or __CHCOO. Most group 1 and 2 metals form strong salts. Strong salts are especially useful when creating conductive compounds as their constituent ions allow for greater conductivity. Weak salts or "weak electrolyte salts" are, as the name suggests, composed of weak electrolytes. They are generally more volatile than strong salts. They may be

neg: Mixture Mixture In chemistry, a mixture is a material made up of two or more different substances which are mixed. A mixture refers to the physical combination of two or more substances in which the identities are retained and are mixed in the form of solutions, suspensions and colloids. Mixtures are one product of mechanically blending or mixing chemical substances such as elements and compounds, without chemical bonding or other chemical change, so that each ingredient substance retains its own chemical properties and makeup. Despite that there are no chemical changes to its constituents, the physical properties of a mixture, such

neg: Silanes Silanes Silanes are saturated chemical compounds consisting of one or multiple silicon atoms linked to each other or one or multiple atoms of other chemical elements as the tetrahedral centers of multiple single bonds. By definition, cycles are excluded, so that the silanes comprise a homologous series of inorganic compounds with the general formula . Commercially available silanes are synthetically derived. Each silicon atom has four bonds (either Si–H or Si–Si bonds), and each hydrogen atom is joined to a silicon atom (H–Si bonds). A series of linked silicon atoms is known as the silicon skeleton or silicon backbone. The

neg: Reactive intermediate Reactive intermediate In chemistry, a reactive intermediate or an intermediate is a short-lived, high-energy, highly reactive molecule. When generated in a chemical reaction, it will quickly convert into a more stable molecule. Only in exceptional cases can these compounds be isolated and stored, e.g. low temperatures, matrix isolation. When their existence is indicated, reactive intermediates can help explain how a chemical reaction takes place. Most chemical reactions take more than one elementary step to complete, and a reactive intermediate is a high-energy, yet stable, product that exists only in one of the intermediate steps. The series of steps together make

neg: Chemical law says that pure chemicals are composed of elements in a definite formulation; we now know that the structural arrangement of these elements is also important. Dalton's law of multiple proportions says that these chemicals will present themselves in proportions that are small whole numbers (i.e. 1:2 O:H in water); although in many systems (notably biomacromolecules and minerals) the ratios tend to require large numbers, and are frequently represented as a fraction. Such compounds are known as non-stoichiometric compounds More modern laws of chemistry define the relationship between energy and transformations. Chemical law Chemical laws are those laws of nature relevant

neg: Functional group Functional group In organic chemistry, functional groups are specific substituents or moieties within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction(s) regardless of the size of the molecule it is a part of. This allows for systematic prediction of chemical reactions and behavior of chemical compounds and design of chemical syntheses. Furthermore, the reactivity of a functional group can be modified by other functional groups nearby. In organic synthesis, functional group interconversion is one of the basic types of transformations. Functional groups are groups

neg: Limnology ecosystems is influenced by natural characteristics and processes including precipitation, underlying soil and bedrock in the watershed, erosion, evaporation, and sedimentation. All bodies of water have a certain composition of both organic and inorganic elements and compounds. Biological reactions also affect the chemical properties of water. In addition to natural processes, human activities strongly influence the chemical composition of aquatic systems and their water quality. Dissolved oxygen and dissolved carbon dioxide are often discussed together due their coupled role in respiration and photosynthesis. Dissolved oxygen concentrations can be altered by physical, chemical, and biological processes and reaction. Physical processes including

neg: Oxygen evolution the cathode to protons to form hydrogen gas. The half reaction, balanced with acid, is: At the positively charged anode, an oxidation reaction occurs, generating oxygen gas and releasing electrons to the anode to complete the circuit: Combining either half reaction pair yields the same overall decomposition of water into oxygen and hydrogen: Chemical oxygen generators consist of chemical compounds that release O upon some stimulation, usually heat. They are used in submarines and commercial aircraft, providing emergency oxygen. Oxygen is generated by high-temperature decomposition of sodium chlorate: Potassium permanganate also releases oxygen upon heating, but the yield is modest.

neg: Geobiology they can fix carbon dioxide for biosynthesis. Plants are photoautotrophs, in that they use the energy of light to fix carbon. Microorganisms employ oxygenic and anoxygenic photoautotrophy, as well as chemoautotrophy. Microbial communities can coordinate in syntrophic metabolisms to shift reaction kinetics in their favor. Many organisms can perform multiple metabolisms to achieve the same end goal; these are called mixotrophs. Biotic metabolism is directly tied to the global cycling of elements and compounds on Earth. The geochemical environment fuels life, which then produces different molecules that go into the external environment. (This is directly relevant to biogeochemistry.) In addition,

neg: Shiina macrolactonization acids with alcohols (Shiina esterification). Both of these intramolecular and intermolecular reactions are used for the artificial synthesis of various natural products and pharmacologically active compounds, as the reaction of a carboxylic acid with an amine produces an amide or a peptide. In acidic reactions, Lewis acid catalysts, such as metal triflates, exhibit high activities, while in basic reactions, 4-dimethylaminopyridine (DMAP), 4-dimethylaminopyridine N-oxide (DMAPO), and 4-pyrrolidinopyridine (PPY) are employed. Shiina macrolactonization Shiina macrolactonization (or Shiina lactonization) is an organic chemical reaction that synthesizes cyclic compounds by using aromatic carboxylic acid anhydrides as dehydration condensation agents. In 1994, Prof. Isamu Shiina