query: What is the chemical symbol for nitrogen?

title: Nitrogen

text: Nitrogen Nitrogen is a chemical element with symbol N and atomic number 7. It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772. Although Carl Wilhelm Scheele and Henry Cavendish had independently done so at about the same time, Rutherford is generally accorded the credit because his work was published first. The name "nitrogène" was suggested by French chemist Jean-Antoine-Claude Chaptal in 1790, when it was found that nitrogen was present in nitric acid and nitrates. Antoine Lavoisier suggested instead the name azote, from the Greek άζωτικός "no life", as it is an asphyxiant gas; this name

title: Nitrogen

text: can cause violent oxidation of organic material. Nitrogen Nitrogen is a chemical element with symbol N and atomic number 7. It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772. Although Carl Wilhelm Scheele and Henry Cavendish had independently done so at about the same time, Rutherford is generally accorded the credit because his work was published first. The name "nitrogène" was suggested by French chemist Jean-Antoine-Claude Chaptal in 1790, when it was found that nitrogen was present in nitric acid and nitrates. Antoine Lavoisier suggested instead the name azote, from the Greek άζωτικός "no life", as

title: Non-protein nitrogen

text: measured based on nitrogen content, as protein is about 16% nitrogen, but, for example, urea is 47% nitrogen. The source of NPN is typically a chemical feed additive, or sometimes chicken waste and cattle manure. Non-protein nitrogen Non-protein nitrogen (or NPN) is a term used in animal nutrition to refer collectively to components such as urea, biuret, and ammonia, which are not proteins but can be converted into proteins by microbes in the ruminant stomach. Due to their lower cost compared to plant and animal proteins their inclusion in a diet can result in economic gain, but at too high

title: Nitrogen fixation

text: Nitrogen fixation Nitrogen fixation is a process by which nitrogen in the Earth's atmosphere is converted into ammonia (NH) or related nitrogenous compounds. Atmospheric nitrogen, which is molecular dinitrogen (N), is relatively nonreactive and is metabolically useless to all but a few microorganisms. The fixation process converts N into ammonia, which is metabolized by most organisms. Nitrogen fixation is essential to life because fixed inorganic nitrogen compounds are required for the biosynthesis of all nitrogen-containing compounds. Therefore, as part of the nitrogen cycle, it is essential for agriculture and the manufacture of fertilizer. It is also, indirectly, relevant to the

title: Nitrogen deficiency

text: a quick method. Nitrogen deficiency All plants require sufficient supplies of macronutrients for healthy growth, and nitrogen (N) is a nutrient that is commonly in limited supply. Nitrogen deficiency in plants can occur when organic matter with high carbon content, such as sawdust, is added to soil. Soil organisms use any nitrogen to break down carbon sources, making N unavailable to plants. This is known as "robbing" the soil of nitrogen. All vegetables apart from nitrogen fixing legumes are prone to this disorder. Nitrogen deficiency can be prevented in the short term by using grass mowings as a mulch, or

title: Nitrogen deficiency

text: Nitrogen deficiency All plants require sufficient supplies of macronutrients for healthy growth, and nitrogen (N) is a nutrient that is commonly in limited supply. Nitrogen deficiency in plants can occur when organic matter with high carbon content, such as sawdust, is added to soil. Soil organisms use any nitrogen to break down carbon sources, making N unavailable to plants. This is known as "robbing" the soil of nitrogen. All vegetables apart from nitrogen fixing legumes are prone to this disorder. Nitrogen deficiency can be prevented in the short term by using grass mowings as a mulch, or foliar feeding with

title: Yeast assimilable nitrogen

text: YAN needed will depend on what the winemaker's goals are for fermentation, particularly whether or not wild fermentation is desired or if the wine will be fully fermented to dryness. The state of the grapes and the conditions of fermentation will influence the amount of nitrogen needed. Fruit that is damaged, moldy or botrytis infected will usually be more depleted of nitrogen (as well as other vitamin resources) when they come in from the vineyard than clean, intact grapes. This depletion can be further exacerbated by over clarification of the must and high sugar content. Wines fermented at higher temperatures

title: Nitrogen fixation package

text: Nitrogen fixation package A nitrogen fixation package is a piece of research equipment for studying nitrogen fixation in plants. One product of this kind, the Q-Box NF1LP made by Qubit Systems, operates by measuring the hydrogen (H) given off in the nitrogen-fixing chemical reaction enabled by nitrogenase enzymes. Nitrogen is produced by bacteria, which have an endo-symbiotic relationship with the legume host. In this relationship, the plant shares its carbohydrates with the bacteria so that the bacteria can thrive, and the plant benefits by having excess nitrogen made available. The bacteria's creation of nitrogen also creates hydrogen, which is what

title: Nitrogen mustard

text: to its use in previous studies, the nitrogen mustard known as "HN2" became the first chemotherapy drug mustine. Nitrogen mustards are not related to the mustard plant or its pungent essence, allyl isothiocyanate; the name comes from the pungent smell of chemical weapons preparations. The original nitrogen mustard drug, mustine (HN2), is no longer commonly in use in its original IV formulation because of excessive toxicity. Other nitrogen mustards developed as treatments include cyclophosphamide, chlorambucil, uramustine, ifosfamide, melphalan, and bendamustine. Bendamustine has recently re-emerged as a viable chemotherapeutic treatment. Nitrogen mustards that can be used for chemical warfare purposes are

title: Nitrogen triiodide

text: alternate method of stain removal is to simply allow the iodine time to sublime. Small amounts of nitrogen triiodide are sometimes synthesized as a demonstration to high school chemistry students or as an act of "chemical magic". To highlight the sensitivity of the compound, it is usually detonated by touching it with a feather but even the slightest air current, laser light, or other movement can cause detonation. Nitrogen triiodide is also notable for being the only known chemical explosive that detonates when exposed to alpha particles and nuclear fission products. Nitrogen triiodide Nitrogen triiodide is the inorganic compound with

title: Nitrogen clathrate

text: water molecules. The large cavity has twelve pentagonal faces, and four hexagonal faces with a cavity radius of 4.73 Å. It is called the hexadecahedral cavity. The symbol for these cavities is 56. The small pentagondodecahedral cavities have twelve pentagon shaped faces and a radius of 3.91 Å. These cavities have a symbol of 5 The large cavities can contain two nitrogen molecules and the small cavities can contain one molecule. The disassociation pressure of nitrogen increases with increasing temperature. At 300K the nitrogen pressure is 2.06 kbar and at 285.6K the pressure is 0.55 kbar. There are four different

title: Chemical element

text: meaning "no life") for "nitrogen". For purposes of international communication and trade, the official names of the chemical elements both ancient and more recently recognized 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 on a Latin or other traditional word, for example adopting "gold" rather than "aurum" as the name for the 79th element (Au). IUPAC prefers the British spellings "aluminium" and "caesium" over the U.S. spellings "aluminum" and "cesium", and the U.S.

title: Nitrogen cycle

text: nitrogen conversion in the oceans. The balanced formula for this "anammox" chemical reaction is: NH + NO → N + 2HO (Δ"G"° = ). Though nitrogen fixation is the primary source of plant-available nitrogen in most ecosystems, in areas with nitrogen-rich bedrock, the breakdown of this rock also serves as a nitrogen source. The nitrogen cycle is an important process in the ocean as well. While the overall cycle is similar, there are different players and modes of transfer for nitrogen in the ocean. Nitrogen enters the water through the precipitation, runoff, or as N from the atmosphere. Nitrogen cannot

title: Nitrogen cycle

text: Nitrogen cycle The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification. The majority of Earth's atmosphere (78%) is atmosphere nitrogen, making it the largest source of nitrogen. However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems. The nitrogen cycle is of particular interest to ecologists because

title: CB military symbol

text: CB military symbol Chemical, biological (CB) — and sometimes radiological — warfare agents were assigned what is termed a military symbol by the U.S. military until the American chemical and biological weapons programs were terminated (in 1990 and 1969, respectively). Military symbols applied to the CB agent fill, and not to the entire weapon. A chemical or biological weapon designation would be, for example, "Aero-14/B", which could be filled with GB, VX, TGB, or with a biological modification kit – OU, NU, UL, etc. A CB weapon is an integrated device of (1) agent, (2) dissemination means, and (3) delivery

title: Nitrogen mustard

text: Nitrogen mustard Nitrogen mustards are cytotoxic chemotherapy agents derived from mustard gas. Although their common use is medicinal, in principle these compounds can also be deployed as chemical warfare agents. Nitrogen mustards are nonspecific DNA alkylating agents. Nitrogen mustard gas was stockpiled by several nations during the Second World War, but it was never used in combat. As with all types of mustard gas, nitrogen mustards are powerful and persistent blister agents and the main examples (HN1, HN2, HN3, see below) are therefore classified as Schedule 1 substances within the Chemical Weapons Convention. Production and use is therefore strongly restricted.

title: Ammoniacal nitrogen

text: water. Ammonia is toxic to fish and humans. The toxicity is decreased with lower alkalinity and increases with higher alkalinity as ammonium is converted to ammonia. There are 3 main forms of nitrogen: Molecular nitrogen is the gas form of nitrogen in the atmosphere. The chemical structure for nitrogen gas is N. The mineral forms of nitrogen are: Ammoniums ions are nitrified and are converted by microorganisms into nitrate. Fish and humans are more tolerant of nitrate nitrogen than they are of ammonium nitrogen. In well aerated water, most of the mineral nitrogen is in the form of nitrate. See

title: CB military symbol

text: or have been, used by the United States: Material Testing Program EA (Edgewood Arsenal) numbers:<br> CB military symbol Chemical, biological (CB) — and sometimes radiological — warfare agents were assigned what is termed a military symbol by the U.S. military until the American chemical and biological weapons programs were terminated (in 1990 and 1969, respectively). Military symbols applied to the CB agent fill, and not to the entire weapon. A chemical or biological weapon designation would be, for example, "Aero-14/B", which could be filled with GB, VX, TGB, or with a biological modification kit – OU, NU, UL, etc. A

title: Nitrogen

text: of N (0.36%) significantly reduces sensitivity, a problem which is only exacerbated by its low gyromagnetic ratio, (only 10.14% that of H). As a result, the signal-to-noise ratio for H is about 300 times as much as that for N at the same magnetic field strength. This may be somewhat alleviated by isotopic enrichment of N by chemical exchange or fractional distillation. N-enriched compounds have the advantage that under standard conditions, they do not undergo chemical exchange of their nitrogen atoms with atmospheric nitrogen, unlike compounds with labelled hydrogen, carbon, and oxygen isotopes that must be kept away from the

title: Symbol (chemistry)

text: Symbol (chemistry) In relation to the chemical elements, a symbol is a code for a chemical element. Many functional groups have their own chemical symbol, e.g. Ph for the phenyl group, and Me for the methyl group. Chemical symbols for elements normally consist of one or two letters from the Latin alphabet, but can contain three when the element has a systematic temporary name (as of March 2017, no discovered elements have such a name), and are written with the first letter capitalized. Earlier chemical element symbols stem from classical Latin and Greek vocabulary. For some elements, this is because

title: Nitrogen fixation package

text: have harmful effects on the Herbaspirillum bacteria needed for fixation. Different aspects of nitrogen fixation can be examined with these products, such as effects of temperature on the fixation process, the regulation of the process by oxygen, and the inhibition of nitrogen fixation by an over-abundance of fertilizers. Nitrogen fixation package A nitrogen fixation package is a piece of research equipment for studying nitrogen fixation in plants. One product of this kind, the Q-Box NF1LP made by Qubit Systems, operates by measuring the hydrogen (H) given off in the nitrogen-fixing chemical reaction enabled by nitrogenase enzymes. Nitrogen is produced by

title: Nitrogen mustard

text: forcing the cell to undergo apoptosis via p53, a protein which scans the genome for defects. Note that the alkylating damage itself is not cytotoxic and does not directly cause cell death. Nitrogen mustard Nitrogen mustards are cytotoxic chemotherapy agents derived from mustard gas. Although their common use is medicinal, in principle these compounds can also be deployed as chemical warfare agents. Nitrogen mustards are nonspecific DNA alkylating agents. Nitrogen mustard gas was stockpiled by several nations during the Second World War, but it was never used in combat. As with all types of mustard gas, nitrogen mustards are powerful

title: Nitrogen cycle

text: nitrogen availability can affect the rate of key ecosystem processes, including primary production and decomposition. Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the global nitrogen cycle. Nitrogen is present in the environment in a wide variety of chemical forms including organic nitrogen, ammonium (NH), nitrite (NO), nitrate (NO), nitrous oxide, (NO), nitric oxide (NO) or inorganic nitrogen gas (N). Organic nitrogen may be in the form of a living organism, humus or in the intermediate products of organic matter decomposition. The processes in the nitrogen cycle

title: Nitrogen

text: hence, only applications of pure nitrogen itself will be considered here. Two-thirds of nitrogen produced by industry is sold as the gas and the remaining one-third as the liquid. The gas is mostly used as an inert atmosphere whenever the oxygen in the air would pose a fire, explosion, or oxidising hazard. Some examples include: Nitrogen is commonly used during sample preparation in chemical analysis. It is used to concentrate and reduce the volume of liquid samples. Directing a pressurised stream of nitrogen gas perpendicular to the surface of the liquid causes the solvent to evaporate while leaving the solute(s)

title: Nitrogen fixation

text: manufacture of all chemical compounds that contain nitrogen, which includes explosives, most pharmaceuticals, and dyes. Nitrogen fixation is carried out naturally in the soil by a wide range of nitrogen fixing Bacteria and Archaea, including "Azotobacter". Some nitrogen-fixing bacteria have symbiotic relationships with some plant groups, especially legumes. Looser relationships between nitrogen-fixing bacteria and plants are often referred to as associative or non-symbiotic, as seen in nitrogen fixation occurring on rice roots. It also occurs naturally in the air by means of NOx production by lightning. All biological nitrogen fixation is effected by enzymes called nitrogenases. These enzymes contain iron,

title: Symbol (chemistry)

text: (namely those in the actinium decay family, the radium decay family, and the thorium decay family) bear placeholder names using the early naming system devised by Ernest Rutherford. General: From organic chemistry: Exotic atoms: Symbol (chemistry) In relation to the chemical elements, a symbol is a code for a chemical element. Many functional groups have their own chemical symbol, e.g. Ph for the phenyl group, and Me for the methyl group. Chemical symbols for elements normally consist of one or two letters from the Latin alphabet, but can contain three when the element has a systematic temporary name (as of

title: HN1 (nitrogen mustard)

text: HN1 (nitrogen mustard) Bis(2-chloroethyl)ethylamine is the organic compound with the formula CHN(CHCHCl). Often abbreviated HN1, it is a powerful vesicant and a nitrogen mustard gas used for chemical warfare. HN1 was developed in the 1920s and 1930s to remove warts and later as a military agent. Because of the latter use, it is a Schedule 1 chemical within the Chemical Weapons Convention and therefore use and production is strongly restricted. It has never been used in warfare. It is an oily liquid with a colorless to pale yellow appearance and a faint fishy or musty odor. HN1 is also an

title: HN1 (nitrogen mustard)

text: mouth because they could damage the gastrointestinal system. HN1 (nitrogen mustard) Bis(2-chloroethyl)ethylamine is the organic compound with the formula CHN(CHCHCl). Often abbreviated HN1, it is a powerful vesicant and a nitrogen mustard gas used for chemical warfare. HN1 was developed in the 1920s and 1930s to remove warts and later as a military agent. Because of the latter use, it is a Schedule 1 chemical within the Chemical Weapons Convention and therefore use and production is strongly restricted. It has never been used in warfare. It is an oily liquid with a colorless to pale yellow appearance and a faint

title: Nitrogen dioxide

text: Nitrogen dioxide Nitrogen dioxide is the chemical compound with the formula . It is one of several nitrogen oxides. is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year which is used primary in production of fertilizers. At higher temperatures it is a reddish-brown gas that has a characteristic sharp, biting odor and is a prominent air pollutant. Nitrogen dioxide is a paramagnetic, bent molecule with C point group symmetry. Nitrogen dioxide is a reddish-brown gas above with a pungent, acrid odor, becomes a yellowish-brown liquid below , and converts to

title: HN3 (nitrogen mustard)

text: HN3 (nitrogen mustard) Tris(2-chloroethyl)amine is the organic compound with the formula N(CHCHCl). Often abbreviated HN3, it is a powerful blister agent and a nitrogen mustard gas (although it is not a gas) used for chemical warfare. HN3 was the last of the nitrogen mustard agents developed. It was designed as a military agent and is the only one of the nitrogen mustards that is still used for military purposes. It is the principal representative of the nitrogen mustards because its vesicant properties are almost equal to those of HD and thus the analogy between the two types of mustard is

title: Nitrogen trifluoride

text: nitrogen trihalides nitrogen trichloride, nitrogen tribromide and nitrogen triiodide, all of which are explosive. Alone among the nitrogen trihalides it has a negative enthalpy of formation. Today, it is prepared both by direct reaction of ammonia and fluorine and by a variation of Ruff's method. It is supplied in pressurized cylinders. NF is slightly soluble in water without undergoing chemical reaction. It is nonbasic with a low dipole moment of 0.2340 D. By contrast, ammonia is basic and highly polar (1.47 D). This difference arises from the fluorine atoms acting as electron withdrawing groups, attracting essentially all of the lone

title: Nitrogen trichloride

text: Nitrogen trichloride Nitrogen trichloride, also known as trichloramine, is the chemical compound with the formula NCl. This yellow, oily, pungent-smelling and explosive liquid is most commonly encountered as a byproduct of chemical reactions between ammonia-derivatives and chlorine (for example, in swimming pools). The compound is prepared by treatment of ammonium salts, such as ammonium nitrate with chlorine. Intermediates in this conversion include chloramine and dichloramine, NHCl and NHCl, respectively. Like ammonia, NCl is a pyramidal molecule. The N-Cl distances are 1.76 Å, and the Cl-N-Cl angles are 107°. The chemistry of NCl has been well explored. It is moderately polar

title: Nitrogen fixation

text: efficient process uses natural gas as a hydrogen source and air as a nitrogen source. Much research has been conducted on the discovery of catalysts for nitrogen fixation, often with the goal of reducing the energy required for this conversion. However, such research has thus far failed to even approach the efficiency and ease of the Haber process. Many compounds react with atmospheric nitrogen to give dinitrogen complexes. The first dinitrogen complex to be reported was Ru(NH)(N). Catalytic chemical nitrogen fixation at ambient conditions is an ongoing scientific endeavor. Guided by the example of nitrogenase, this area of homogeneous catalysis

title: Nitrogen-15 tracing

text: be a bias by changing natural nitrogen transformations. In agricultural soil, however, application of N enriched tracers, such as ammonium and nitrate, resembles conventional fertilisation practise. A way to calculate nitrogen transformation rates in soil can be achieved by numerical approximation that takes different, simultaneous nitrogen transformations into account. A numerical tool to study the nitrogen cycle is the N model based on a Markov chain Monte Carlo simulation. Nitrogen-15 tracing Nitrogen-15 (N) tracing is a technique to study the nitrogen cycle using the heavier, stable nitrogen isotope N. Despite the different weights, N is involved in the same chemical

title: Nitrogen dioxide

text: NO exposure concentrations near roadways are of particular concern for susceptible individuals, including asthmatics, children, and the elderly. For limits in other countries see the table in the "Ambient air quality criteria" article. Nitrogen dioxide Nitrogen dioxide is the chemical compound with the formula . It is one of several nitrogen oxides. is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year which is used primary in production of fertilizers. At higher temperatures it is a reddish-brown gas that has a characteristic sharp, biting odor and is a prominent air pollutant.

title: Lichens and nitrogen cycling

text: heaths. Lichens and nitrogen cycling The nitrogen cycle is one of the Earth’s biogeochemical cycle that involves the conversion of nitrogen into different chemical forms. The main processes of the nitrogen cycle are the fixation, ammonification, nitrification, and denitrification. As one of the macronutrients, nitrogen plays an important role in plant growth. Both nitrogen-fixing lichens and non-nitrogen fixing lichens absorb the nitrogen as the one of the nutrient. Different environments have different factors that contributes or affect the nitrogen cycle. For example, in the subarctic heath, increase in temperature can cause N2 fixation to increase or decrease based on season

title: Lichens and nitrogen cycling

text: Lichens and nitrogen cycling The nitrogen cycle is one of the Earth’s biogeochemical cycle that involves the conversion of nitrogen into different chemical forms. The main processes of the nitrogen cycle are the fixation, ammonification, nitrification, and denitrification. As one of the macronutrients, nitrogen plays an important role in plant growth. Both nitrogen-fixing lichens and non-nitrogen fixing lichens absorb the nitrogen as the one of the nutrient. Different environments have different factors that contributes or affect the nitrogen cycle. For example, in the subarctic heath, increase in temperature can cause N2 fixation to increase or decrease based on season while

title: Terra Nitrogen Company

text: Terra Nitrogen Company Terra Nitrogen Company, Limited Partnership is an American company that was set up on September 20, 1991 and now is headquartered in Deerfield, Illinois. The company markets nitrogen fertilizers, most of which are anhydrous ammonia and urea ammonium nitrate solutions (UAN). Terra Nitrogen Company (TNCLP) is a subsidiary of CF Industries and Terra Nitrogen, L. P. (TNLP) is the operating partner of TNCLP. Terra Nitrogen Company's parental company is CF Industries, a leading global fertilizer and chemical company, with 3,000 employees and 9 manufacturing plants operating in Canada, the United Kingdom and the United States. Their Donaldsonville,

title: Lichens and nitrogen cycling

text: population. While costly, in regions where nitrogen availability is low, fixation process is the main way for the lichen to absorb nitrogen which is macronutrient (essential nutrient). Nitrogen, as a macronutrient and a biogeochemical cycle, also affects the ecology. Through the nitrogen cycle, it breaks down into the chemical form that allows plants to absorb as nutrients. There are certain regions in the world that most plants can not live due to harsh environments as well as lack of nutrients such as nitrogen. That means that at in some regions, the biogeochemical cycle (including nitrogen cycle and carbon cycle) is

title: Nitrogen-15 tracing

text: Nitrogen-15 tracing Nitrogen-15 (N) tracing is a technique to study the nitrogen cycle using the heavier, stable nitrogen isotope N. Despite the different weights, N is involved in the same chemical reactions as the more abundant N and is therefore used to trace and quantify conversions of one nitrogen compound to another. N tracing is applied in biogeochemistry, soil science, environmental science and environmental microbiology. N tracing allows researchers to distinguish specific nitrogen conversions from a network of simultaneous reactions; e.g. ammonium can at the same time be oxidised by autotrophic microorganisms, produced by mineralisation of organic matter, produced by

title: Solid nitrogen

text: Solid nitrogen is used as a matrix on which to store and study reactive chemical species, such as free radicals or isolated atoms. One use is to study dinitrogen complexes of metals in isolation from other molecules. Solid nitrogen forms a large part of the surface of Pluto and the Neptunian moon Triton. On Pluto it was directly observed for the first time in July 2015 by the "New Horizons" space probe and on Triton it was directly observed by the "Voyager 2" space probe in August 1989. On Triton, solid nitrogen takes the form of frost crystals and a

title: Nitrogen

text: be tetravalent in quaternary ammonium salts, RN), with a lone pair that can confer basicity on the compound by being coordinated to a proton. This may be offset by other factors: for example, amides are not basic because the lone pair is delocalised into a double bond (though they may act as acids at very low pH, being protonated at the oxygen), and pyrrole is not acidic because the lone pair is delocalised as part of an aromatic ring. The amount of nitrogen in a chemical substance can be determined by the Kjeldahl method. In particular, nitrogen is an essential

title: Nitrogen rule

text: common chemical elements in neutral organic compounds (hydrogen, carbon, nitrogen, oxygen, silicon, phosphorus, sulfur, and the halogens), elements with even numbered nominal masses form even numbers of covalent bonds, while elements with odd numbered nominal masses form odd numbers of covalent bonds, with the exception of nitrogen, which has a nominal (or integer) mass of 14, but has a valency of 3. The nitrogen rule is only true for neutral structures in which all of the atoms in the molecule have a number of covalent bonds equal to their standard valency (counting each sigma bond and pi bond as a

title: Isotopes of nitrogen

text: isotopes of carbon, while most of the isotopes with masses above 15 decay to isotopes of oxygen. The shortest-lived known isotope is nitrogen-10, with a half-life of about 2.3 microseconds. Nitrogen-14 is one of two stable (non-radioactive) isotopes of the chemical element nitrogen, which makes about 99.636% of natural nitrogen. Nitrogen-14 is one of the very few stable nuclides with both an odd number of protons and of neutrons (seven each) and is the only one to make up a majority of its element. Each of proton or neutron contributes a nuclear spin of plus or minus spin 1/2, giving

title: Hazard symbol

text: carry a significant health risk (biohazards), including viral samples and used hypodermic needles (see sharps waste). The biohazard symbol was developed by the Dow Chemical Company in 1966 for their containment products. According to Charles Baldwin, an environmental-health engineer who contributed to its development: "We wanted something that was memorable but meaningless, so we could educate people as to what it means." In an article in "Science" in 1967, the symbol was presented as the new standard for all biological hazards ("biohazards"). The article explained that over 40 symbols were drawn up by Dow artists, and all of the symbols

title: Nitrogen

text: Middle Ages. Alchemists knew nitric acid as "aqua fortis" (strong water), as well as other nitrogen compounds such as ammonium salts and nitrate salts. The mixture of nitric and hydrochloric acids was known as "aqua regia" (royal water), celebrated for its ability to dissolve gold, the king of metals. The discovery of nitrogen is attributed to the Scottish physician Daniel Rutherford in 1772, who called it "noxious air". Though he did not recognise it as an entirely different chemical substance, he clearly distinguished it from Joseph Black's "fixed air", or carbon dioxide. The fact that there was a component of

title: Nitrogen trichloride

text: due to safety concerns. Nitrogen trichloride can irritate mucous membranes—it is a lachrymatory agent, but has never been used as such. The pure substance (rarely encountered) is a dangerous explosive, being sensitive to light, heat, even moderate shock, and organic compounds. Pierre Louis Dulong first prepared it in 1812, and lost two fingers and an eye in two explosions. In 1813, an NCl explosion blinded Sir Humphry Davy temporarily, inducing him to hire Michael Faraday as a co-worker. They were both injured in another NCl explosion shortly thereafter. Nitrogen trichloride Nitrogen trichloride, also known as trichloramine, is the chemical compound

title: Nitrogen-vacancy center

text: high-energy particles are suitable for such irradiation, including electrons, protons, neutrons, ions, and gamma photons. Irradiation produces lattice vacancies, which are a part of N-V centers. Those vacancies are immobile at room temperature, and annealing is required to move them. Single substitutional nitrogen produces strain in the diamond lattice; it therefore efficiently captures moving vacancies, producing the N-V centers. During chemical vapor deposition of diamond, a small fraction of single substitutional nitrogen impurity (typically <0.5%) traps vacancies generated as a result of the plasma synthesis. Such nitrogen-vacancy centers are preferentially aligned to the growth direction. Diamond is notorious for having

title: Liquid nitrogen engine

text: engine. Liquid nitrogen production is an energy-intensive process. Currently practical refrigeration plants producing a few tons/day of liquid nitrogen operate at about 50% of Carnot efficiency. Currently surplus liquid nitrogen is produced as a byproduct in the production of liquid oxygen. Any process that relies on a phase-change of a substance will have much lower energy densities than processes involving a chemical reaction in a substance, which in turn have lower energy densities than nuclear reactions. Liquid nitrogen as an energy store has a low energy density. Liquid hydrocarbon fuels, by comparison, have a high energy density. A high energy

title: Yeast assimilable nitrogen

text: is the primary form of assimilable nitrogen available to yeast. However, at crushing the juice may contain anywhere from 0 to 150 mg/L of ammonium salts, depending on the how much nitrogen the grapevine received in the vineyard. In the cell, the inorganic ammonia and ammonium ions get "fixed" through a series of chemical reactions that ultimately yields the organic nitrogen source glutamate. The ammonium ion also serves as an allosteric regulator for one of the enzymes used in glycolysis and may also have an effect on how the yeast cell transports glucose and fructose into the cell. The proteins

title: Nitrogen-doped carbon nanotube

text: Nitrogen-doped carbon nanotube Nitrogen-doped carbon nanotubes (N-CNTs) can be produced through five main methods; chemical vapor deposition, high-temperature and high-pressure reactions, gas-solid reaction of amorphous carbon with NH at high temperature, solid reaction, and solvothermal synthesis. N-CNTs can also be prepared by a CVD method of pyrolyzing melamine under Ar at elevated temperatures of 800–980 °C. However synthesis by CVD of melamine results in the formation of bamboo-structured CNTs. XPS spectra of grown N-CNTs reveal nitrogen in five main components, pyridinic nitrogen, pyrrolic nitrogen, quaternary nitrogen, and nitrogen oxides. Furthermore, synthesis temperature affects the type of nitrogen configuration. Nitrogen doping

title: Nitrogen

text: oxygen, and specially purified grades containing at most 2 ppm oxygen and 10 ppm argon are also available. In a chemical laboratory, it is prepared by treating an aqueous solution of ammonium chloride with sodium nitrite. Small amounts of the impurities NO and HNO are also formed in this reaction. The impurities can be removed by passing the gas through aqueous sulfuric acid containing potassium dichromate. Very pure nitrogen can be prepared by the thermal decomposition of barium azide or sodium azide. The applications of nitrogen compounds are naturally extremely widely varied due to the huge size of this class:

title: Chemical tanker

text: smooth and thus easier to clean using permanently fitted tank cleaning machines. Cargo tanks, either empty or filled, are normally protected against explosion by inert gas blankets. Often nitrogen is the inert gas used, supplied either from portable gas bottles or a Nitrogen generator. Most new chemical tankers are built by shipbuilders in Japan, Korea or China, with other builders in Turkey, Italy, Germany and Poland. Japanese shipbuilders now account for the large majority of stainless steel chemical tankers built, as welding stainless steel to the accuracy required for cargo tank construction is a skill which is difficult to acquire.

title: Nitrogen cycle

text: result of extensive cultivation of legumes (particularly soy, alfalfa, and clover), growing use of the Haber–Bosch process in the creation of chemical fertilizers, and pollution emitted by vehicles and industrial plants, human beings have more than doubled the annual transfer of nitrogen into biologically available forms. In addition, humans have significantly contributed to the transfer of nitrogen trace gases from Earth to the atmosphere and from the land to aquatic systems. Human alterations to the global nitrogen cycle are most intense in developed countries and in Asia, where vehicle emissions and industrial agriculture are highest. Nitrous oxide (NO) has risen

title: Chemical oxygen generator

text: gas separation. In the case of oxygen generation a zeolite-based sieve forces preferential adsorption for nitrogen. Clean, dry air is passed through the sieve beds on the oxygen generator, producing an oxygen-enriched gas. Nitrogen separation membrane equipment is also used. Chemical oxygen generators are used in aircraft, breathing apparatus for firefighters and mine rescue crews, submarines, and everywhere a compact emergency oxygen generator with long shelf life is needed. They usually contain a device for absorption of carbon dioxide, sometimes a filter filled with lithium hydroxide; a kilogram of LiOH absorbs about half a kilogram of CO. Chemical oxygen generator

title: HN3 (nitrogen mustard)

text: toxic than the sulfur mustards. HN-3 can be absorbed into the body by inhalation, ingestion, eye contact, and skin contact (though inhalation is the most common). The chemical is extremely toxic and may damage the eyes, skin, and respiratory tract and suppress the immune system. HN-3 penetrates and binds quickly to cells of the body, but its health effects develop slowly. The full extent of cellular injury may not be known for days. HN3 (nitrogen mustard) Tris(2-chloroethyl)amine is the organic compound with the formula N(CHCHCl). Often abbreviated HN3, it is a powerful blister agent and a nitrogen mustard gas (although

title: Symbol (chemistry)

text: (see Chemical elements in East Asian languages). However, Latin symbols are also used, especially in formulas. A list of current, dated, as well as proposed and historical signs and symbols is included here with its signification. Also given is each element's atomic number, atomic weight or the atomic mass of the most stable isotope, group and period numbers on the periodic table, and etymology of the symbol. Hazard pictographs are another type of symbols used in chemistry. Antimatter atoms are denoted by a bar above the symbol for their matter counterpart, so e.g. H is the symbol for antihydrogen. The

title: CB military symbol

text: by the United States – signifying crude mustard. In the Second World War the purity of mustard gas was improved through distillation, and this purified chemical warfare agent was designated HD. When it was mixed with a thickener (Agent VV), it was given the symbol HV. Today mustard gas is indicated by the single capital letter H, but HD is still in common use. Military symbols can also reflect the name of where a chemical agent is manufactured. For example, chloropicrin has the symbol PS, which was derived from the British town in which it was manufactured during the First

title: Symbol

text: "symbol", which he used to stand for something that is unknown and that cannot be made clear or precise. An example of a symbol in this sense is Christ as a symbol of the archetype called "self". For example, written languages are composed of a variety of different symbols that create words, p. . Through these written words humans communicate with each other. Kenneth Burke described "Homo sapiens" as a "symbol-using, symbol making, and symbol misusing animal" to suggest that a person creates symbols as well as misuses them. One example he uses to indicate what he means by the

title: Chemical looping combustion

text: a dual fluidized bed circulating reactor system and a moving bed-fluidized bed circulating reactor system. Isolation of the fuel from air simplifies the number of chemical reactions in combustion. Employing oxygen without nitrogen and the trace gases found in air eliminates the primary source for the formation of nitrogen oxide (), produces a flue gas composed primarily of carbon dioxide and water vapor; other trace pollutants depend on the fuel selected. Chemical looping combustion (CLC) uses two or more reactions to perform the oxidation of hydrocarbon based fuels. In its simplest form, an oxygen carrying species (normally a metal) is

title: What Is the What

text: What Is the What What Is the What: The Autobiography of Valentino Achak Deng is a 2006 novel written by Dave Eggers. It is based on the life of Valentino Achak Deng, a Sudanese child refugee who immigrated to the United States under the Lost Boys of Sudan program. It was a finalist for the National Book Award. As a boy, Achak is separated from his family during the Second Sudanese Civil War when the Arab militia, referred to as "murahaleen" (which is Arabic for the deported), wipes out his Dinka village, Marial Bai. During the assault, he loses sight

title: Chemical kinetics

text: the rate of a chemical reaction, thermodynamics determines the extent to which reactions occur. In a reversible reaction, chemical equilibrium is reached when the rates of the forward and reverse reactions are equal [the principle of dynamic equilibrium ] and the concentrations of the reactants and Products no longer change. This is demonstrated by, for example, the Haber–Bosch process for combining nitrogen and hydrogen to produce ammonia. Chemical clock reactions such as the Belousov–Zhabotinsky reaction demonstrate that component concentrations can oscillate for a long time before finally attaining the equilibrium. In general terms, the free energy change (ΔG) of a

title: Chemical element

text: 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

title: What Is the What

text: That Happens Will Happen Today". Tom Tykwer plans to adapt the novel into a film. In 2009, the novel received the Prix Médicis étranger in France. What Is the What What Is the What: The Autobiography of Valentino Achak Deng is a 2006 novel written by Dave Eggers. It is based on the life of Valentino Achak Deng, a Sudanese child refugee who immigrated to the United States under the Lost Boys of Sudan program. It was a finalist for the National Book Award. As a boy, Achak is separated from his family during the Second Sudanese Civil War when

title: Chemical element

text: 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

title: Nitrogen-vacancy center

text: S=1 pair with one of the vacancy electrons. As in N-V, the vacancy electrons are "exchanging roles" preserving the overall trigonal symmetry. This N-V state is what is commonly, and somewhat incorrectly, called "the nitrogen-vacancy center". The neutral state has not yet been explored for spin manipulations. The N-V centers are randomly oriented within a diamond crystal. Ion implantation techniques can enable their artificial creation in predetermined positions. Nitrogen-vacancy centers are typically produced from single substitutional nitrogen centers (called C or P1 centers in diamond literature) by irradiation followed by annealing at temperatures above 700 °C. A wide range of

title: The Nitrogen Fix

text: The Nitrogen Fix The Nitrogen Fix is a 1980 science fiction novel by Hal Clement, and illustrators David B. Mattingly, and Janet Aulisio. The plot revolves around a nomadic family in a future where all oxygen in the Earth's atmosphere has combined with nitrogen, so the atmosphere is mostly nitrogen with traces of water, nitrogen oxides and carbon dioxide, and the seas are very dilute nitric acid. The family is allied with an alien, an octopus-like being, who can survive in the new atmosphere. Humans must live in shelters with oxygen-generating plants, or use suitable breathing equipment. Some of Earth's

title: Nitrogen

text: melts at −210 °C and boils at −196 °C. Dinitrogen is mostly unreactive at room temperature, but it will nevertheless react with lithium metal and some transition metal complexes. This is due to its bonding, which is unique among the diatomic elements at standard conditions in that it has an N≡N triple bond. Triple bonds have short bond lengths (in this case, 109.76 pm) and high dissociation energies (in this case, 945.41 kJ/mol), and are thus very strong, explaining dinitrogen's chemical inertness. There are some theoretical indications that other nitrogen oligomers and polymers may be possible. If they could be

title: Nitrogen

text: products of the amino acids ornithine and lysine, respectively, in decaying proteins. Nitrogen gas is an industrial gas produced by the fractional distillation of liquid air, or by mechanical means using gaseous air (pressurised reverse osmosis membrane or pressure swing adsorption). Nitrogen gas generators using membranes or pressure swing adsorption (PSA) are typically more cost and energy efficient than bulk delivered nitrogen. Commercial nitrogen is often a byproduct of air-processing for industrial concentration of oxygen for steelmaking and other purposes. When supplied compressed in cylinders it is often called OFN (oxygen-free nitrogen). Commercial-grade nitrogen already contains at most 20 ppm

title: Nitrogen

text: "chemical magic". Chlorine azide (ClN) and bromine azide (BrN) are extremely sensitive and explosive. Two series of nitrogen oxohalides are known: the nitrosyl halides (XNO) and the nitryl halides (XNO). The first are very reactive gases that can be made by directly halogenating nitrous oxide. Nitrosyl fluoride (NOF) is colourless and a vigorous fluorinating agent. Nitrosyl chloride (NOCl) behaves in much the same way and has often been used as an ionising solvent. Nitrosyl bromide (NOBr) is red. The reactions of the nitryl halides are mostly similar: nitryl fluoride (FNO) and nitryl chloride (ClNO) are likewise reactive gases and vigorous

title: Chemical oceanography

text: the cycles of the biologically active elements such as carbon, nitrogen, and phosphorus as well as those of some important trace elements such as iron. Another important area of study in chemical oceanography is the behaviour of isotopes (see isotope geochemistry) and how they can be used as tracers of past and present oceanographic and climatic processes. For example, the incidence of O (the heavy isotope of oxygen) can be used as an indicator of polar ice sheet extent, and boron isotopes are key indicators of the pH and CO content of oceans in the geologic past. Chemical oceanography Chemical

title: Symbol

text: Symbol A symbol is a mark, sign or word that indicates, signifies, or is understood as representing an idea, object, or relationship. Symbols allow people to go beyond what is known or seen by creating linkages between otherwise very different concepts and experiences. All communication (and data processing) is achieved through the use of symbols. Symbols take the form of words, sounds, gestures, ideas or visual images and are used to convey other ideas and beliefs. For example, a red octagon may be a symbol for "STOP". On a map, a blue line might represent a river. Numerals are symbols

title: Term symbol

text: database, neutral atoms are identified as I, singly ionized atoms as II, etc. Neutral atoms of the chemical elements have the same term symbol "for each column" in the s-block and p-block elements, but may differ in d-block and f-block elements, if the ground state electron configuration changes within a column. Ground state term symbols for chemical elements are given below. For light atoms, the spin-orbit interaction (or coupling) is small so that the total orbital angular momentum "L" and total spin "S" are good quantum numbers. The interaction between "L" and "S" is known as "LS coupling," "Russell-Saunders" "coupling"

title: Hazard symbol

text: under is drawn from the distance to the perimeter of the equilateral triangle that forms between the centers of the three intersecting circles. An outer circle of the ring under is drawn and finally enclosed with the arcs from the center of the inner circles with a shorter radius from the inner circles. A chemical hazard symbol is a pictogram applied to containers of dangerous chemical compounds to indicate the specific hazard, and thus the required precautions. There are several systems of labels, depending on the purpose, such as on the container for end use, or on a vehicle during

title: Lichens and nitrogen cycling

text: lichen, can't perform the same process. The nitrogen fixation is energetically costly due to chemical transformation and only about 10% of lichen are partnered with cyanobacteria. In agricultural region, non N2 fixing lichen reflect uptake of NH3 emission indicating that it have lower nitrogen value. Some lichens such as Placopsis gelada contain both N2 fixing phototrophs and non N2-fixing phototrophs in which Nostoc (cyanobacteria, the phototrophic N2 fixer) was dwelling within cephalodia (small gall like structure within lichen; contains cyanobacteria symbionts). In such cases, heterocyst differentiation was greater in cephalodia when compared to having Nostoc as the primary symbionts in

title: Symbol table

text: global scope, whether it is imported, and what namespace it belongs to. Some programming languages allow the symbol table to be manipulated at run-time, so that symbols can be added at any time. Racket is an example of such a language. Both the LISP and the Scheme programming languages allow arbitrary, generic properties to be associated with each symbol. The Prolog programming language is essentially a symbol-table manipulation language; symbols are called "atoms", and the relationships between symbols can be reasoned over. Similarly, OpenCog provides a dynamic symbol table, called the "atomspace", which is used for knowledge representation. Symbol table

title: Nitrogen-doped carbon nanotube

text: plays a pivotal role in lithium storage, as it creates defects in the CNT walls allowing for Li ions to diffuse into interwall space. It also increases capacity by providing more favorable bind of N-doped sites. N-CNTs are also much more reactive to metal oxide nanoparticle deposition which can further enhance storage capacity, especially in anode materials for Li-ion batteries. However boron-doped nanotubes have been shown to make batteries with triple capacity. Nitrogen-doped carbon nanotube Nitrogen-doped carbon nanotubes (N-CNTs) can be produced through five main methods; chemical vapor deposition, high-temperature and high-pressure reactions, gas-solid reaction of amorphous carbon with NH

title: Symbol

text: Hence, "outward sign" of something. The meaning "something which stands for something else" was first recorded in 1590, in Edmund Spenser's "Faerie Queene". In considering the effect of a symbol on the psyche, in his seminal essay "The Symbol without Meaning" Joseph Campbell proposes the following definition: "A symbol is an energy evoking, and directing, agent". Later, expanding on what he means by this definition Campbell says: Jared Elisha defined symbolism that is something that stands for another, it can be place, object, or a person Heinrich Zimmer gives a concise overview of the nature, and perennial relevance, of symbols.

title: Chemical industry

text: tend to be the largest volume, though much smaller in dollar revenue terms due to their low prices. The top 11 of the 100 chemicals in 2000 were sulfuric acid (44 million tons), nitrogen (34), ethylene (28), oxygen (27), lime (22), ammonia (17), propylene (16), polyethylene (15), chlorine (13), phosphoric acid (13) and diammonium phosphates (12). The largest chemical producers today are global companies with international operations and plants in numerous countries. A list of the top 25 chemical companies by chemical sales in 2015 appears below. (Note: Chemical sales represent only a portion of total sales for some companies.)

title: Nitrogen balance

text: dietary protein requirements. Determining dietary protein requirements using nitrogen balance requires that all nitrogen inputs and losses are carefully collected, to ensure that all nitrogen exchange is accounted for. In order to control nitrogen inputs and losses, nitrogen balance studies usually require participants to eat very specific diets (so total nitrogen intake is known) and stay in the study location for the duration of the study (to collect all nitrogen losses). Because of these conditions, it can be difficult to study the dietary protein requirements of certain populations using the nitrogen balance technique (e.g. children). Dietary nitrogen, from metabolising proteins

title: Nitrogen balance

text: and other nitrogen-containing compounds, has been linked to changes in genome evolution. Species which primarily obtain energy from metabolising nitrogen-rich compounds use more nitrogen in their DNA than species which primarily break down carbohydrates for their energy (Needs Ref). Dietary nitrogen alters codon bias and genome composition in parasitic microorganisms. Nitrogen balance Nitrogen balance is a measure of nitrogen input minus nitrogen output. Nitrogen Balance = Nitrogen intake - Nitrogen loss Sources of nitrogen intake include meat, dairy, eggs, nuts and legumes, and grains and cereals. Examples of nitrogen losses include urine, feces, sweat, hair, and skin. Blood urea nitrogen

title: Nitrogen inversion

text: Nitrogen inversion In chemistry, nitrogen inversion is a fluxional process in nitrogen and amines, whereby the molecule "turns inside out". It is a rapid oscillation of the nitrogen atom and substituents, the nitrogen "moving" through the plane formed by the substituents (although the substituents also move - in the other direction); the molecule passing through a planar transition state. For a compound that would otherwise be chiral due to a nitrogen stereocenter, nitrogen inversion provides a low energy pathway for racemization, usually making chiral resolution impossible. Nitrogen inversion is one case of the more general phenomenon of pyramidal inversion, which

title: Ministry of the Chemical Industry (Soviet Union)

text: Ministry of the Chemical Industry (Soviet Union) The Ministry of Chemical Industry (Minkhimprom; ) was a government ministry in the Soviet Union. The People's Commissariat of Chemical Industry was to coordinate and direct the following branches of the chemical industry: nitrogen, basic chemistry, mineral chemical, lacquer and paint, aniline dye, iodine and bromine, rubber, caoutchouc, and plastics. By ukase of the Presidium of the Supreme Soviet of 28 March 1941, the People's Commissariat of Rubber Industry USSR was established. It was to include enterprises producing caoutchouc, rubber, tires, and asbestos. The People's Commissariat of Chemical Industry and the People's Commissariat

title: Naming of chemical elements

text: element carbon. Even for elements such as nitrogen having only one stable allotrope, a name such as dinitrogen may be used to indicate its molecular structure N as well as its elemental composition. The naming of chemical compounds comprising more than one element is a complex subject, discussed at length in the article on chemical nomenclature. Naming of chemical elements Chemical elements may be named from various sources: sometimes based on the person who discovered it, or the place it was discovered. Some have Latin or Greek roots deriving from something related to the element, for example some use to

title: Chemical cycling

text: the lithosphere are known as geochemical cycles. Ongoing geochemical cycles are one of the main attributes of geologically active worlds. A chemical cycle involving a biosphere is known as a biogeochemical cycle. In most hydrogen-fusing stars, including the Sun, a chemical cycle involved in stellar nucleosynthesis occurs which is known as a carbon-nitrogen-oxygen or (CNO cycle). In addition to this cycle, stars also have a helium cycle. Various cycles involving gas and dust have been found to occur in galaxies. The majority of known chemical cycles on Venus involve its dense atmosphere and compounds of carbon and sulphur, the most

title: Chemical element

text: "Sb" (stibium) for antimony. Chemical symbols are understood internationally when element names might require translation. There have sometimes been differences in the past. For example, Germans in the past have used "J" (for the alternate name Jod) for iodine, but now use "I" and "Iod". The first letter of a chemical symbol is always capitalized, as in the preceding examples, and the subsequent letters, if any, are always lower case (small letters). Thus, the symbols for californium and einsteinium are Cf and Es. There are also symbols in chemical equations for groups of chemical elements, for example in comparative formulas.

title: HN3 (nitrogen mustard)

text: the strongest. As a vesicant the use and production is strongly restricted within the Chemical Weapons Convention where it is classified as a Schedule 1 substance. Nitrogen mustards react via an initial cyclization to the corresponding quaternary aziridine salt. The rate of this reaction is pH dependent because the protonated amine cannot cyclize. HN-3 has found some applications in chemotherapy, e.g., for Hodgkin's disease, and in some compound semiconductor research but it is mainly of interest for its military uses and is the only one of these agents that remains anywhere as a military agent. These agents are more immediately

title: Nitrogen

text: nitrogen is a constituent of organic compounds as diverse as Kevlar used in high-strength fabric and cyanoacrylate used in superglue. Nitrogen is a constituent of every major pharmacological drug class, including antibiotics. Many drugs are mimics or prodrugs of natural nitrogen-containing signal molecules: for example, the organic nitrates nitroglycerin and nitroprusside control blood pressure by metabolizing into nitric oxide. Many notable nitrogen-containing drugs, such as the natural caffeine and morphine or the synthetic amphetamines, act on receptors of animal neurotransmitters. Nitrogen compounds have a very long history, ammonium chloride having been known to Herodotus. They were well known by the

title: Nitrogen

text: they may release so much energy on collision with even such stable molecules as carbon dioxide and water to cause homolytic fission into radicals such as CO and O or OH and H. Atomic nitrogen is prepared by passing an electric discharge through nitrogen gas at 0.1–2 mmHg, which produces atomic nitrogen along with a peach-yellow emission that fades slowly as an afterglow for several minutes even after the discharge terminates. Given the great reactivity of atomic nitrogen, elemental nitrogen usually occurs as molecular N, dinitrogen. This molecule is a colourless, odourless, and tasteless diamagnetic gas at standard conditions: it

title: Nitrogen generator

text: Nitrogen generator Nitrogen generators and stations are stationary or mobile air-to-nitrogen production complexes. The adsorption gas separation process in nitrogen generators is based on the phenomenon of fixing various gas mixture components by a solid substance called an adsorbent. This phenomenon is brought about by the gas and adsorbent molecules' interaction. The technology of air-to-nitrogen production with the use of adsorption processes in nitrogen generators is well studied and widely applied at industrial facilities for the recovery of high-purity nitrogen. The operating principle of a nitrogen generator utilizing the adsorption technology is based upon the dependence of the adsorption rates

title: Nitrogen assimilation

text: Nitrogen assimilation Nitrogen assimilation is the formation of organic nitrogen compounds like amino acids from inorganic nitrogen compounds present in the environment. Organisms like plants, fungi and certain bacteria that cannot fix nitrogen gas (N) depend on the ability to assimilate nitrate or ammonia for their needs. Other organisms, like animals, depend entirely on organic nitrogen from their food. Plants absorb nitrogen from the soil in the form of nitrate (NO) and ammonium (NH). In aerobic soils where nitrification can occur, nitrate is usually the predominant form of available nitrogen that is absorbed. However this need not always be the

title: Chemical cycling

text: important role in sustaining the biosphere. Notable active chemical cycles on Earth include: Other chemical cycles include hydrogen peroxide. Recent evidence suggests that similar chemical cycles to Earth's occur on a lesser scale on Mars, facilitated by the thin atmosphere, including carbon dioxide (and possibly carbon), water, sulphur, methane, oxygen, ozone, and nitrogen cycles. Many studies point to significantly more active chemical cycles on Mars in the past, however the faint young Sun paradox has proved problematic in determining chemical cycles involved in early climate models of the planet. Jupiter, like all the gas giants, has an atmospheric methane cycle.

text: of qualified specialists, and to reduce administrative costs. "Source": Ministry of the Chemical Industry (Soviet Union) The Ministry of Chemical Industry (Minkhimprom; ) was a government ministry in the Soviet Union. The People's Commissariat of Chemical Industry was to coordinate and direct the following branches of the chemical industry: nitrogen, basic chemistry, mineral chemical, lacquer and paint, aniline dye, iodine and bromine, rubber, caoutchouc, and plastics. By ukase of the Presidium of the Supreme Soviet of 28 March 1941, the People's Commissariat of Rubber Industry USSR was established. It was to include enterprises producing caoutchouc, rubber, tires, and asbestos. The

title: Nitrogen balance

text: Nitrogen balance Nitrogen balance is a measure of nitrogen input minus nitrogen output. Nitrogen Balance = Nitrogen intake - Nitrogen loss Sources of nitrogen intake include meat, dairy, eggs, nuts and legumes, and grains and cereals. Examples of nitrogen losses include urine, feces, sweat, hair, and skin. Blood urea nitrogen can be used in estimating nitrogen balance, as can the urea concentration in urine. Nitrogen is a fundamental component of amino acids, which are the molecular building blocks of protein. Therefore, measuring nitrogen inputs and losses can be used to study protein metabolism. Positive nitrogen balance is associated with periods

title: Nitrogen

text: the industrial synthesis of ammonia and nitric acid became common. Nitrogen compounds constantly interchange between the atmosphere and living organisms. Nitrogen must first be processed, or "fixed", into a plant-usable form, usually ammonia. Some nitrogen fixation is done by lightning strikes producing the nitrogen oxides, but most is done by diazotrophic bacteria through enzymes known as nitrogenases (although today industrial nitrogen fixation to ammonia is also significant). When the ammonia is taken up by plants, it is used to synthesise proteins. These plants are then digested by animals who use the nitrogen compounds to synthesise their own proteins and excrete

title: Nitrogen trifluoride

text: and thin-film solar cells. Nitrogen trifluoride is also used in hydrogen fluoride and deuterium fluoride lasers, which are types of chemical lasers. It is preferred to fluorine gas due to its convenient handling properties, reflecting its considerable stability. It is compatible with steel and Monel, as well as several plastics. is a greenhouse gas, with a global warming potential (GWP) 17,200 times greater than that of when compared over a 100-year period. Its GWP place it second only to in the group of Kyoto-recognised greenhouse gases, and was included in that grouping with effect from 2013 and the commencement of

title: Reactive nitrogen

text: Reactive nitrogen Reactive nitrogen ("Nr") is a term used for a variety of nitrogen compounds that support growth directly or indirectly. Representative species include the gases nitrogen oxides (NO), ammonia (NH), nitrous oxide (NO), as well as the anion nitrate (NO). Most of these species are the result of intensive farming, especially the (mis)use of fertilizers. Although required for life, nitrogen is stored in the biosphere in an unreactive ("unfixed") form N, which supports on a few life forms. Reactive nitrogen is however "fixed" and is readily converted into protein, which supports life, leading to depletion of oxygen in fresh

title: FeMoco

text: FeMoco FeMoco ( cofactor) is the primary cofactor of nitrogenase. Nitrogenase is the enzyme that catalyzes the conversion of atmospheric nitrogen molecules N into ammonia (NH) through the process known as nitrogen fixation. Containing iron and molybdenum, the cofactor is called FeMoco. Its stoichiometry is FeMoSC. The FeMo cofactor is a cluster with composition FeMoSC. Fe is the chemical symbol for the element iron (ferrum), and Mo is the symbol for molybdenum. This large cluster can be viewed as two subunits composed of one FeS (iron(III) sulfide) cluster and one MoFeS cluster. The two clusters are linked by three sulfide

title: Nitrogen

text: a reinforced concrete beam immediately below it, and blow the walls of the laboratory 0.1–0.2 m off their foundations. Liquid nitrogen readily evaporates to form gaseous nitrogen, and hence the precautions associated with gaseous nitrogen also apply to liquid nitrogen. For example, oxygen sensors are sometimes used as a safety precaution when working with liquid nitrogen to alert workers of gas spills into a confined space. Vessels containing liquid nitrogen can condense oxygen from air. The liquid in such a vessel becomes increasingly enriched in oxygen (boiling point −183 °C, higher than that of nitrogen) as the nitrogen evaporates, and

title: Chemical equilibrium

text: molecule (negative for reactants, positive for products) and "R" is the symbol for the "j" th molecule, a properly balanced equation will obey: Multiplying the first equilibrium condition by ν yields As above, defining ΔG which will be zero at equilibrium. Chemical equilibrium In a chemical reaction, chemical equilibrium is the state in which both reactants and products are present in concentrations which have no further tendency to change with time, so that there is no observable change in the properties of the system. Usually, this state results when the forward reaction proceeds at the same rate as the reverse