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a chemical technician but more experience. There are also degrees specific to become a chemical technologist, which are somewhat distinct from those required when a student is interested in becoming a professional chemist. A Chemical technologist is more involved in the management and operation of the equipment and ins...	{ "page_id": 5636, "title": "Chemist" }
other factors, so this makes it difficult to categorize the exact roles of these chemistry-related workers as standard for that given level of education. Because of these factors affecting exact job titles with distinct responsibilities, some chemists might begin doing technician tasks while other chemists might begin ...	{ "page_id": 5636, "title": "Chemist" }
their education and experience as a chemist with a distinct credential to provide different services (e.g., forensic chemists, chemistry-related software development, patent law specialists, environmental law firm staff, scientific news reporting staff, engineering design staff, etc.). In comparison, chemists who have ...	{ "page_id": 5636, "title": "Chemist" }
colleges (including some smaller four-year colleges or smaller non-research universities for undergraduates) as well as community colleges usually hire chemists with a M.S. as professors too (and rarely, some big universities who need part-time or temporary instructors, or temporary staff), but when the positions are s...	{ "page_id": 5636, "title": "Chemist" }
chemistry are closely related, for example, in medicinal chemistry. Inorganic chemistry is the study of the properties and reactions of inorganic compounds. The distinction between organic and inorganic disciplines is not absolute and there is much overlap, most importantly in the sub-discipline of organometallic chemi...	{ "page_id": 5636, "title": "Chemist" }
history of chemistry, materials science, medical science, molecular biology, molecular genetics, nanotechnology, nuclear chemistry, oenology, organometallic chemistry, petrochemistry, pharmacology, photochemistry, phytochemistry, polymer chemistry, supramolecular chemistry and surface chemistry. == Professional societi...	{ "page_id": 5636, "title": "Chemist" }
Hose barbs are cylindrical pieces or parts for attaching and securing hoses. The barb-like rings on the cylindrical piece allow for an easy push-connection of flexible plastic or rubber tubing that is not easily disconnected. Hose barbs are used in machine perfusion and chemistry laboratory equipment. Hose barb fitting...	{ "page_id": 22943237, "title": "Hose barb" }
Durnavirales is an order of double-stranded RNA viruses which infect eukaryotes. The name of the group derives from Italian duplo which means double (a reference to double-stranded), rna for the type of virus, and -virales which is the suffix for a virus order. == Families == The order contains the follow families: Ama...	{ "page_id": 63772166, "title": "Durnavirales" }
Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combustion does not always result in fire, because a flame is only visible when substa...	{ "page_id": 5638, "title": "Combustion" }
ash). Thus, the produced smoke is usually toxic and contains unburned or partially oxidized products. Any combustion at high temperatures in atmospheric air, which is 78 percent nitrogen, will also create small amounts of several nitrogen oxides, commonly referred to as NOx, since the combustion of nitrogen is thermody...	{ "page_id": 5638, "title": "Combustion" }
primarily the most common oxides. Carbon will yield carbon dioxide, sulfur will yield sulfur dioxide, and iron will yield iron(III) oxide. Nitrogen is not considered to be a combustible substance when oxygen is the oxidant. Still, small amounts of various nitrogen oxides (commonly designated NOx species) form when the ...	{ "page_id": 5638, "title": "Combustion" }
fuel to react completely to produce carbon dioxide and water. It also happens when the combustion is quenched by a heat sink, such as a solid surface or flame trap. As is the case with complete combustion, water is produced by incomplete combustion; however, carbon and carbon monoxide are produced instead of carbon dio...	{ "page_id": 5638, "title": "Combustion" }
of the hemoglobin in the blood, rendering it unable to transport oxygen. ==== Problems associated with incomplete combustion ==== ===== Environmental problems ===== These oxides combine with water and oxygen in the atmosphere, creating nitric acid and sulfuric acids, which return to Earth's surface as acid deposition, ...	{ "page_id": 5638, "title": "Combustion" }
wildfires. === Spontaneous === Spontaneous combustion is a type of combustion that occurs by self-heating (increase in temperature due to exothermic internal reactions), followed by thermal runaway (self-heating which rapidly accelerates to high temperatures) and finally, ignition. For example, phosphorus self-ignites ...	{ "page_id": 5638, "title": "Combustion" }
the chemical equation for stoichiometric combustion of a hydrocarbon in oxygen is: C x H y + ( x + y 4 ) O 2 ⟶ x CO 2 + y 2 H 2 O {\displaystyle {\ce {C}}_{x}{\ce {H}}_{y}+\left(x+{y \over 4}\right){\ce {O2->}}x{\ce {CO2}}+{y \over 2}{\ce {H2O}}} For example, the stoichiometric combustion of methane in oxygen is: CH 4 ...	{ "page_id": 5638, "title": "Combustion" }
γ 2 ) ( O 2 + 3.77 N 2 ) ⟶ α CO 2 + β 2 H 2 O + 3.77 ( α + β 4 − γ 2 ) N 2 {\displaystyle {\ce {C_{\mathit {\alpha }}H_{\mathit {\beta }}O_{\mathit {\gamma }}}}+\left(\alpha +{\frac {\beta }{4}}-{\frac {\gamma }{2}}\right)\left({\ce {O_{2}}}+3.77{\ce {N_{2}}}\right)\longrightarrow \alpha {\ce {CO_{2}}}+{\frac {\beta }{...	{ "page_id": 5638, "title": "Combustion" }
) ⟶ α CO 2 + β − δ 2 H 2 O + δ HF + 3.77 ( α + β − δ 4 − γ 2 ) N 2 {\displaystyle {\ce {C_{\mathit {\alpha }}H_{\mathit {\beta }}O_{\mathit {\gamma }}F_{\mathit {\delta }}}}+\left(\alpha +{\frac {\beta -\delta }{4}}-{\frac {\gamma }{2}}\right)\left({\ce {O_{2}}}+3.77{\ce {N_{2}}}\right)\longrightarrow \alpha {\ce {CO_{...	{ "page_id": 5638, "title": "Combustion" }
of a hydrocarbon in oxygen is: C x H y fuel + z O 2 oxygen ⟶ a CO 2 carbon dioxide + b CO carbon monoxide + c H 2 O water + d H 2 hydrogen {\displaystyle {\ce {{\underset {fuel}{C_{\mathit {x}}H_{\mathit {y}}}}+{\underset {oxygen}{{\mathit {z}}O2}}->{\underset {carbon\ dioxide}{{\mathit {a}}CO2}}+{\underset {carbon\ mo...	{ "page_id": 5638, "title": "Combustion" }
CO and about 0.5% CH4. Substances or materials which undergo combustion are called fuels. The most common examples are natural gas, propane, kerosene, diesel, petrol, charcoal, coal, wood, etc. === Liquid fuels === Combustion of a liquid fuel in an oxidizing atmosphere actually happens in the gas phase. It is the vapor...	{ "page_id": 5638, "title": "Combustion" }
solid maintains the evolution of flammable vapours. Charcoal phase or solid phase, when the output of flammable gases from the material is too low for the persistent presence of flame and the charred fuel does not burn rapidly and just glows and later only smoulders. == Combustion management == Efficient process heatin...	{ "page_id": 5638, "title": "Combustion" }
Minimizing excess oxygen pays an additional benefit: for a given offgas temperature, the NOx level is lowest when excess oxygen is kept lowest. Adherence to these two principles is furthered by making material and heat balances on the combustion process. The material balance directly relates the air/fuel ratio to the p...	{ "page_id": 5638, "title": "Combustion" }
fuel radicals and oxidizing radicals. Oxidizing species include singlet oxygen, hydroxyl, monatomic oxygen, and hydroperoxyl. Such intermediates are short-lived and cannot be isolated. However, non-radical intermediates are stable and are produced in incomplete combustion. An example is acetaldehyde produced in the com...	{ "page_id": 5638, "title": "Combustion" }
detail levels. Examples are provided by: The Relaxation Redistribution Method (RRM) The Intrinsic Low-Dimensional Manifold (ILDM) approach and further developments The invariant-constrained equilibrium edge preimage curve method. A few variational approaches The Computational Singular perturbation (CSP) method and furt...	{ "page_id": 5638, "title": "Combustion" }
the more common way of expressing the usage of more than the stoichiometric combustion air is percent excess combustion air. For example, excess combustion air of 15 percent means that 15 percent more than the required stoichiometric air is being used. == Instabilities == Combustion instabilities are typically violent ...	{ "page_id": 5638, "title": "Combustion" }
reading == Poinsot, Thierry; Veynante, Denis (2012). Theoretical and Numerical Combustion (3rd ed.). European Centre for Research and Advanced Training in Scientific Computation. Archived from the original on 2017-09-12. Retrieved 2011-11-18. Lackner, Maximilian; Winter, Franz; Agarwal, Avinash K., eds. (2010). Handboo...	{ "page_id": 5638, "title": "Combustion" }
Discovered in 1937 by Robin Hill, Hill reagents allowed the discovery of electron transport chains during photosynthesis. These are dyes that act as artificial electron acceptors, changing color when they are reduced. An example of a Hill reagent is 2,6-dichlorophenolindophenol (DCPIP). == References == David Alan Walk...	{ "page_id": 17634827, "title": "Hill reagent" }
Neutral detergent fiber (NDF) is the most common measure of fiber used for animal feed analysis, but it does not represent a unique class of chemical compounds. NDF measures most of the structural components in plant cells (i.e. lignin, hemicellulose and cellulose), but not pectin. Further analysis can be done to the s...	{ "page_id": 10032652, "title": "Neutral detergent fiber" }
Peripolar cells are specialized epithelial cells. Peripolar cells are located within Bowman's capsule at its vascular pole. These cells were discovered at the vascular pole of the sheep glomerulus. The cells contain numerous cytoplasmic granules. The granules in peripolar cells are secretory, and the cells show feature...	{ "page_id": 77796881, "title": "Peripolar cell" }
Pisoniviricetes is a class of positive-strand RNA viruses which infect eukaryotes. A characteristic of the group is a conserved 3C-like protease from the PA clan of proteases for processing the translated polyprotein. The name of the group is a portmanteau of member orders "picornavirales, sobelivirales, nidovirales" a...	{ "page_id": 63772180, "title": "Pisoniviricetes" }
The medulla is a horizontal layer within a lichen thallus. It is a loosely arranged layer of interlaced hyphae below the upper cortex and photobiont zone, but above the lower cortex. The medulla generally has a cottony appearance. It is the widest layer of a heteromerous lichen thallus. == References ==	{ "page_id": 27072027, "title": "Medulla (lichenology)" }
Sobelivirales is an order of RNA viruses which infect eukaryotes. Member viruses have a positive-sense single-stranded RNA genome. The name of the group is a portmanteau of member orders "sobemovirus-like" and -virales which is the suffix for a virus order. == Taxonomy == The following families are recognized: Alvernav...	{ "page_id": 63772189, "title": "Sobelivirales" }
Polysporangiophytes, also called polysporangiates or formally Polysporangiophyta, are plants in which the spore-bearing generation (sporophyte) has branching stems (axes) that bear sporangia. The name literally means 'many sporangia plant'. The clade includes all land plants (embryophytes) except for the bryophytes (li...	{ "page_id": 14161438, "title": "Polysporangiophyte" }
million years ago). The fossils were better-preserved than Dawson's, and showed clearly that these early land plants did indeed consist of generally naked vertical stems arising from similar horizontal structures. The vertical stems were dichotomously branched with some branches ending in sporangia. Since these discove...	{ "page_id": 14161438, "title": "Polysporangiophyte" }
subdivision. These groups have since been treated at the ranks of division, class and order. A variety of names have been used, which the table below summarizes. For Banks, rhyniophytes comprised simple leafless plants with terminal sporangia (e.g., Cooksonia, Rhynia) with centrarch xylem; zosterophylls comprised plant...	{ "page_id": 14161438, "title": "Polysporangiophyte" }
early polysporangiophytes that is consistent with Kenrick and Crane's cladistic analysis and subsequent research, though Cantino et al. have published a Phylocode classification. Banks' three groups continue to be used for convenience. == Phylogeny == A major cladistic study of land plants was published in 1997 by Kenr...	{ "page_id": 14161438, "title": "Polysporangiophyte" }
might suggest that both the gametophyte-dominant life style of bryophytes and the sporophyte-dominant life style of vascular plants evolved from this isomorphic condition. They were leafless and did not have true vascular tissues. In particular, they did not have tracheids: elongated cells that help transport water and...	{ "page_id": 14161438, "title": "Polysporangiophyte" }
no other remains are known. Some early plants may have had heteromorphic alternation of generations, with later acquisition of isomorphic gametophytes in certain lineages. The cladogram above shows the 'protracheophytes' diverging earlier than the lycophytes; however, lycophytes were present in the Ludfordian stage of ...	{ "page_id": 14161438, "title": "Polysporangiophyte" }
A fluorescence microscope is an optical microscope that uses fluorescence instead of, or in addition to, scattering, reflection, and attenuation or absorption, to study the properties of organic or inorganic substances. A fluorescence microscope is any microscope that uses fluorescence to generate an image, whether it ...	{ "page_id": 1185308, "title": "Fluorescence microscope" }
the life sciences, are of the epifluorescence design shown in the diagram. Light of the excitation wavelength illuminates the specimen through the objective lens. The fluorescence emitted by the specimen is focused to the detector by the same objective that is used for the excitation which for greater resolution will n...	{ "page_id": 1185308, "title": "Fluorescence microscope" }
which allows the specific and sensitive staining of a specimen in order to detect the distribution of proteins or other molecules of interest. As a result, there is a diverse range of techniques for fluorescent staining of biological samples. === Biological fluorescent stains === Many fluorescent stains have been desig...	{ "page_id": 1185308, "title": "Fluorescence microscope" }
primary antibody. Alternatively a secondary antibody, conjugated to a fluorophore, which binds specifically to the first antibody can be used. For example, a primary antibody raised in a mouse which recognises tubulin combined with a secondary anti-mouse antibody derivatised with a fluorophore could be used to label mi...	{ "page_id": 1185308, "title": "Fluorescence microscope" }
these approaches involve training a deep convolutional neural network on stained cells and then estimating the fluorescence on unstained samples. Thus by decoupling the cells under investigation from the cells used to train the network, imaging can performed quicker and with reduced phototoxicity. == Sub-diffraction te...	{ "page_id": 1185308, "title": "Fluorescence microscope" }
between light and fluorescing molecules. The molecules are driven strongly between distinguishable molecular states at each specific location, so that finally light can be emitted at only a small fraction of space, hence an increased resolution. As well in the 1990s another super resolution microscopy method based on w...	{ "page_id": 1185308, "title": "Fluorescence microscope" }
Multiple kernel learning refers to a set of machine learning methods that use a predefined set of kernels and learn an optimal linear or non-linear combination of kernels as part of the algorithm. Reasons to use multiple kernel learning include a) the ability to select for an optimal kernel and parameters from a larger...	{ "page_id": 44635680, "title": "Multiple kernel learning" }
can then be written as min β , c E ( Y , K ′ c ) + R ( K , c ) {\displaystyle \min _{\beta ,c}\mathrm {E} (Y,K'c)+R(K,c)} where E {\displaystyle \mathrm {E} } is an error function and R {\displaystyle R} is a regularization term. E {\displaystyle \mathrm {E} } is typically the square loss function (Tikhonov regularizat...	{ "page_id": 44635680, "title": "Multiple kernel learning" }
use a combination function that is parameterized. The parameters are generally defined for each individual kernel based on single-kernel performance or some computation from the kernel matrix. Examples of these include the kernel from Tenabe et al. (2008). Letting π m {\displaystyle \pi _{m}} be the accuracy obtained u...	{ "page_id": 44635680, "title": "Multiple kernel learning" }
that have been used include linear approaches, such as that used by Lanckriet et al. (2002). We can define the implausibility of a kernel ω ( K ) {\displaystyle \omega (K)} to be the value of the objective function after solving a canonical SVM problem. We can then solve the following minimization problem: min tr ⁡ ( K...	{ "page_id": 44635680, "title": "Multiple kernel learning" }
K m ( x i m , x m ) + b {\displaystyle f(x)=\sum _{i=1}^{N}\sum _{m=1}^{P}\alpha _{i}^{m}K_{m}(x_{i}^{m},x^{m})+b} The parameters α i m {\displaystyle \alpha _{i}^{m}} and b {\displaystyle b} are learned by gradient descent on a coordinate basis. In this way, each iteration of the descent algorithm identifies the best ...	{ "page_id": 44635680, "title": "Multiple kernel learning" }
ϕ m π , ψ m ( x ) ⟩ {\displaystyle g_{m}^{\pi }(x)=\langle \phi _{m}^{\pi },\psi _{m}(x)\rangle } where ψ m ( x ) = [ K m ( x 1 , x ) , … , K m ( x L , x ) ] T {\displaystyle \psi _{m}(x)=[K_{m}(x_{1},x),\ldots ,K_{m}(x_{L},x)]^{T}} (the kernel distance between the labeled data and all of the labeled and unlabeled data...	{ "page_id": 44635680, "title": "Multiple kernel learning" }
{\displaystyle U={x_{i}}} be a set of unlabeled data. The kernel definition is the linear combined kernel K ′ = ∑ i = 1 M β i K m {\displaystyle K'=\sum _{i=1}^{M}\beta _{i}K_{m}} . In this problem, the data needs to be "clustered" into groups based on the kernel distances. Let B i {\displaystyle B_{i}} be a group or c...	{ "page_id": 44635680, "title": "Multiple kernel learning" }
x j {\displaystyle x_{j}} are neighbors. Then, B i = x j : D i j = 1 {\displaystyle B_{i}={x_{j}:D_{ij}=1}} . Note that these groups must be learned as well. Zhuang et al. solve this problem by an alternating minimization method for K {\displaystyle K} and the groups B i {\displaystyle B_{i}} . For more information, se...	{ "page_id": 44635680, "title": "Multiple kernel learning" }
Nutriomics is the science that studies the food and nutrition domains comprehensively to improve consumer's well-being and health. More specifically Nutriomics approaches are used to evaluate the effects of different diets to promote health and modulate the risk of disease development. == See also == Nutrigenomics Func...	{ "page_id": 19142174, "title": "Nutriomics" }
In the domain of physics and probability, the filters, random fields, and maximum entropy (FRAME) model is a Markov random field model (or a Gibbs distribution) of stationary spatial processes, in which the energy function is the sum of translation-invariant potential functions that are one-dimensional non-linear trans...	{ "page_id": 64689698, "title": "Filters, random fields, and maximum entropy model" }
the FRAME model by a ConvNet structure and learn all parameters from scratch. The deep FRAME model is the first framework that integrates modern deep neural network from deep learning and Gibbs distribution from statistical physics. The deep FRAME models are further generalized to modeling video patterns, 3D volumetric...	{ "page_id": 64689698, "title": "Filters, random fields, and maximum entropy model" }
A chemical element is a chemical substance whose atoms all have the same number of protons. The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8: each oxygen atom has 8 protons in its nucleus. Atoms of the same element can have different numbers of neutrons in...	{ "page_id": 5659, "title": "Chemical element" }
atom", the terms "elementary substance" and "simple substance" have been suggested, but they have not gained much acceptance in English chemical literature, whereas in some other languages their equivalent is widely used. For example, French distinguishes élément chimique (kind of atoms) and corps simple (chemical subs...	{ "page_id": 5659, "title": "Chemical element" }
2016, the International Union of Pure and Applied Chemistry (IUPAC) recognized a total of 118 elements. The first 94 occur naturally on Earth, and the remaining 24 are synthetic elements produced in nuclear reactions. Save for unstable radioactive elements (radioelements) which decay quickly, nearly all elements are av...	{ "page_id": 5659, "title": "Chemical element" }
At 2×1019 years, over 109 times the estimated age of the universe, bismuth-209 has the longest known alpha decay half-life of any nuclide, and is almost always considered on par with the 80 stable elements. The heaviest elements (those beyond plutonium, element 94) are radioactive, with half-lives so short that they ar...	{ "page_id": 5659, "title": "Chemical element" }
pattern of artificial production and later natural discovery has been repeated with several other radioactive naturally occurring rare elements. Lists of elements are available by name, atomic number, density, melting point, boiling point and chemical symbol, as well as ionization energy. The nuclides of stable and rad...	{ "page_id": 5659, "title": "Chemical element" }
(that is, with the same number of protons in their nucleus), but having different numbers of neutrons. Thus, for example, there are three main isotopes of carbon. All carbon atoms have 6 protons, but they can have either 6, 7, or 8 neutrons. Since the mass numbers of these are 12, 13 and 14 respectively, said three iso...	{ "page_id": 5659, "title": "Chemical element" }
number of an element, A, is the number of nucleons (protons and neutrons) in the atomic nucleus. Different isotopes of a given element are distinguished by their mass number, which is written as a superscript on the left hand side of the chemical symbol (e.g., 238U). The mass number is always an integer and has units o...	{ "page_id": 5659, "title": "Chemical element" }
of an element is the average of the atomic masses of all the chemical element's isotopes as found in a particular environment, weighted by isotopic abundance, relative to the atomic mass unit. This number may be a fraction that is not close to a whole number. For example, the relative atomic mass of chlorine is 35.453 ...	{ "page_id": 5659, "title": "Chemical element" }
has layers of carbon atoms with a hexagonal structure stacked on top of each other; graphene, which is a single layer of graphite that is very strong; fullerenes, which have nearly spherical shapes; and carbon nanotubes, which are tubes with a hexagonal structure (even these may differ from each other in electrical pro...	{ "page_id": 5659, "title": "Chemical element" }
and nonmetals. The version of this classification used in the periodic tables presented here includes: actinides, alkali metals, alkaline earth metals, halogens, lanthanides, transition metals, post-transition metals, metalloids, reactive nonmetals, and noble gases. In this system, the alkali metals, alkaline earth met...	{ "page_id": 5659, "title": "Chemical element" }
when liquefied or solidified, the gaseous elements have densities similar to those of the other elements. When an element has allotropes with different densities, one representative allotrope is typically selected in summary presentations, while densities for each allotrope can be stated where more detail is provided. ...	{ "page_id": 5659, "title": "Chemical element" }
with very long half-lives: for example, the half-lives predicted for the observationally stable lead isotopes range from 1035 to 10189 years. Elements with atomic numbers 43, 61, and 83 through 94 are unstable enough that their radioactive decay can be detected. Three of these elements, bismuth (element 83), thorium (9...	{ "page_id": 5659, "title": "Chemical element" }
science, engineering, agriculture, medicine, nutrition, environmental health, and astronomy. Its principles are especially important in chemical engineering. == Nomenclature and symbols == The various chemical elements are formally identified by their unique atomic numbers, their accepted names, and their chemical symb...	{ "page_id": 5659, "title": "Chemical element" }
trade, the official names of the chemical elements both ancient and more recently recognised are decided by the International Union of Pure and Applied Chemistry (IUPAC), which has decided on a sort of international English language, drawing on traditional English names even when an element's chemical symbol is based o...	{ "page_id": 5659, "title": "Chemical element" }
Paris, France. The Germans were reluctant to relinquish naming rights to the French, often calling it cassiopeium. Similarly, the British discoverer of niobium originally named it columbium, in reference to the New World. It was used extensively as such by American publications before the international standardisation ...	{ "page_id": 5659, "title": "Chemical element" }
gold, "Ag" (Latin argentum) for silver, "Pb" (Latin plumbum) for lead, "Cu" (Latin cuprum) for copper, and "Sb" (Latin stibium) for antimony. The three other mismatches between Neo-Latin (as used by Berzelius) and English names are "Na" (Neo-Latin natrium) for sodium, "K" (Neo-Latin kalium) for potassium, and "W" (Neo-...	{ "page_id": 5659, "title": "Chemical element" }
in comparative formulas. These are often a single capital letter, and the letters are reserved and not used for names of specific elements. For example, "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 lette...	{ "page_id": 5659, "title": "Chemical element" }
2H2O. == Origin of the elements == Only about 4% of the total mass of the universe is made of atoms or ions, and thus represented by elements. This fraction is about 15% of the total matter, with the remainder of the matter (85%) being dark matter. The nature of dark matter is unknown, but it is not composed of atoms o...	{ "page_id": 5659, "title": "Chemical element" }
atoms (or ions) consisted of ~75% 1H, 25% 4He, and 0.01% deuterium, with only tiny traces of lithium, beryllium, and perhaps boron. Subsequent enrichment of galactic halos occurred due to stellar nucleosynthesis and supernova nucleosynthesis. However, the element abundance in intergalactic space can still closely resem...	{ "page_id": 5659, "title": "Chemical element" }
more distant galaxies are being viewed as they appeared in the past, so their abundances of elements appear closer to the primordial mixture. As physical laws and processes appear common throughout the visible universe, however, scientists expect that these galaxies evolved elements in similar abundance. The abundance ...	{ "page_id": 5659, "title": "Chemical element" }
volatile neon, carbon (as hydrocarbons), nitrogen and sulfur, as a result of solar heating in the early formation of the Solar System. Oxygen, the most abundant Earth element by mass, is retained on Earth by combination with silicon. Aluminium at 8% by mass is more common in the Earth's crust than in the universe and s...	{ "page_id": 5659, "title": "Chemical element" }
the composition of inorganic and organic bodies and is a speculative treatise on chemistry. Plato believed the elements introduced a century earlier by Empedocles were composed of small polyhedral forms: tetrahedron (fire), octahedron (air), icosahedron (water), and cube (earth). Aristotle, c. 350 BCE, also used the te...	{ "page_id": 5659, "title": "Chemical element" }
used the concept of "corpuscles"—or "atomes", as he also called them—to explain how a limited number of elements could combine into a vast number of compounds. Propos. I. ... At the first Production of mixt Bodies, the Universal Matter whereof they ... consisted, was actually divided into little Particles. ... The Gene...	{ "page_id": 5659, "title": "Chemical element" }
(whether Three, Four or Five, or fewer or more) of Substances ... The Chymists are wont to call the Ingredients of mixt Bodies, Principles, as the Aristotelians name them Elements. ... Principles ... as not being compounded of any more primary Bodies: and Elements, in regard that all mix'd Bodies are compounded of them...	{ "page_id": 5659, "title": "Chemical element" }
45 of the 49 then-accepted elements. Dmitri Mendeleev had 63 elements in his 1869 periodic table. From Boyle until the early 20th century, an element was defined as a pure substance that cannot be decomposed into any simpler substance and cannot be transformed into other elements by chemical processes. Elements at the ...	{ "page_id": 5659, "title": "Chemical element" }
bismuth, were recognised as distinct substances before 1500 AD. Phosphorus, cobalt, and platinum were isolated before 1750. Most of the remaining naturally occurring elements were identified and characterised by 1900, including: Such now-familiar industrial materials as aluminium, silicon, nickel, chromium, magnesium, ...	{ "page_id": 5659, "title": "Chemical element" }
the latest element claimed to be discovered, in 2009. On 28 November 2016, scientists at the IUPAC officially recognised the names for the four newest elements, with atomic numbers 113, 115, 117, and 118. == List of the 118 known chemical elements == The following sortable table shows the 118 known elements. Atomic num...	{ "page_id": 5659, "title": "Chemical element" }
Wilkinson, eds. (1997). Compendium of Chemical Terminology (2nd ed.). Oxford: Blackwell Scientific Publications. doi:10.1351/goldbook. ISBN 978-0-9678550-9-7. XML on-line corrected version: created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins == External links == Videos for each element by the Univers...	{ "page_id": 5659, "title": "Chemical element" }
The molecular formula C15H10O (molar mass: 206.239 g/mol, exact mass: 206.0732 u) may refer to: Anthracene-9-carbaldehyde Diphenylcyclopropenone (diphencyprone)	{ "page_id": 32183839, "title": "C15H10O" }
Chlorine is a chemical element; it has symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is a yellow-green gas at room temperature. It is an extremely reactive element and a...	{ "page_id": 5667, "title": "Chlorine" }
in the manufacture of a wide range of consumer products, about two-thirds of them organic chemicals such as polyvinyl chloride (PVC), many intermediates for the production of plastics, and other end products which do not contain the element. As a common disinfectant, elemental chlorine and chlorine-generating compounds...	{ "page_id": 5667, "title": "Chlorine" }
was the synthesis of mercury(II) chloride (corrosive sublimate), whose production from the heating of mercury either with alum and ammonium chloride or with vitriol and sodium chloride was first described in the De aluminibus et salibus ("On Alums and Salts", an eleventh- or twelfth century Arabic text falsely attribut...	{ "page_id": 5667, "title": "Chlorine" }
both translating into English as acid substance), so a number of chemists, including Claude Berthollet, suggested that Scheele's dephlogisticated muriatic acid air must be a combination of oxygen and the yet undiscovered element, muriaticum. In 1809, Joseph Louis Gay-Lussac and Louis-Jacques Thénard tried to decompose ...	{ "page_id": 5667, "title": "Chlorine" }
and alternative production methods were sought. Scottish chemist and industrialist Charles Tennant first produced a solution of calcium hypochlorite ("chlorinated lime"), then solid calcium hypochlorite (bleaching powder). These compounds produced low levels of elemental chlorine and could be more efficiently transport...	{ "page_id": 5667, "title": "Chlorine" }
two. Chlorine has the electron configuration [Ne]3s23p5, with the seven electrons in the third and outermost shell acting as its valence electrons. Like all halogens, it is thus one electron short of a full octet, and is hence a strong oxidising agent, reacting with many elements in order to complete its outer shell. C...	{ "page_id": 5667, "title": "Chlorine" }
yellow gas, chlorine is distinctly yellow-green. This trend occurs because the wavelengths of visible light absorbed by the halogens increase down the group. Specifically, the colour of a halogen, such as chlorine, results from the electron transition between the highest occupied antibonding πg molecular orbital and th...	{ "page_id": 5667, "title": "Chlorine" }
is 36Cl. The primary decay mode of isotopes lighter than 35Cl is electron capture to isotopes of sulfur; that of isotopes heavier than 37Cl is beta decay to isotopes of argon; and 36Cl may decay by either mode to stable 36S or 36Ar. 36Cl occurs in trace quantities in nature as a cosmogenic nuclide in a ratio of about (...	{ "page_id": 5667, "title": "Chlorine" }
reaction are unfavorable, and there is also a bubble overpotential effect to consider, so that electrolysis of aqueous chloride solutions evolves chlorine gas and not oxygen gas, a fact that is very useful for the industrial production of chlorine. === Hydrogen chloride === The simplest chlorine compound is hydrogen ch...	{ "page_id": 5667, "title": "Chlorine" }
distillation. Unlike hydrogen fluoride, anhydrous liquid hydrogen chloride is difficult to work with as a solvent, because its boiling point is low, it has a small liquid range, its dielectric constant is low and it does not dissociate appreciably into H2Cl+ and HCl−2 ions – the latter, in any case, are much less stabl...	{ "page_id": 5667, "title": "Chlorine" }
with Cl2 usually leads to a higher oxidation state than bromination with Br2 when multiple oxidation states are available, such as in MoCl5 and MoBr3. Chlorides can be made by reaction of an element or its oxide, hydroxide, or carbonate with hydrochloric acid, and then dehydrated by mildly high temperatures combined wi...	{ "page_id": 5667, "title": "Chlorine" }
cation. This is very unstable and has only been characterised by its electronic band spectrum when produced in a low-pressure discharge tube. The yellow [Cl3]+ cation is more stable and may be produced as follows: Cl2 + ClF + AsF5 −78 °C⟶ [Cl3]+[AsF6]− This reaction is conducted in the oxidising solvent arsenic pentafl...	{ "page_id": 5667, "title": "Chlorine" }
2 ClF ⟶ 2 HF + Cl2O Chlorine trifluoride (ClF3) is a volatile colourless molecular liquid which melts at −76.3 °C and boils at 11.8 °C. It may be formed by directly fluorinating gaseous chlorine or chlorine monofluoride at 200–300 °C. One of the most reactive chemical compounds known, the list of elements it sets on fi...	{ "page_id": 5667, "title": "Chlorine" }
atm, and on a small scale by reacting metal chlorides with fluorine gas at 100–300 °C. It melts at −103 °C and boils at −13.1 °C. It is a very strong fluorinating agent, although it is still not as effective as chlorine trifluoride. Only a few specific stoichiometric reactions have been characterised. Arsenic pentafluo...	{ "page_id": 5667, "title": "Chlorine" }
gas (deep-red as a solid or liquid), as expected from its having an odd number of electrons: it is stable towards dimerisation due to the delocalisation of the unpaired electron. It explodes above −40 °C as a liquid and under pressure as a gas and therefore must be made at low concentrations for wood-pulp bleaching and...	{ "page_id": 5667, "title": "Chlorine" }
stable but still moisture-sensitive and highly reactive). Dichlorine hexoxide is a dark-red liquid that freezes to form a solid which turns yellow at −180 °C: it is usually made by reaction of chlorine dioxide with oxygen. Despite attempts to rationalise it as the dimer of ClO3, it reacts more as though it were chloryl...	{ "page_id": 5667, "title": "Chlorine" }
to form chloride and perchlorate (4 ClO−3 ⇌ Cl− + 3 ClO−4) but this is still very slow even at 100 °C despite the very favourable equilibrium constant of 1020. The rates of reaction for the chlorine oxyanions increases as the oxidation state of chlorine decreases. The strengths of the chlorine oxyacids increase very qu...	{ "page_id": 5667, "title": "Chlorine" }

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