Synthetically produced ammonia and nitrates are key industrial fertilisers, and fertiliser nitrates are key pollutants in the eutrophication of water systems.
Introduction
Nitrogen
Nitrogen | Introduction
Synthetically produced nitrogenous compounds like ammonia and nitrates are key industrial fertilisers, and fertiliser nitrates are key pollutants in the eutrophication of water systems. Synthetically produced ammonia and nitrates are key industrial fertilisers, and fertiliser nitrates are key pollutants in the eutrophication of water systems. Synthetically produced ammonia and nitrates are key industrial fertilisers, and fertiliser nitrates are key pollutants in the eutrophication of water systems. : Many industrially important compounds, such as ammonia, nitric acid, organic nitrates,  and cyanides, contain nitrogen, synthetically  produced ammonia and nitrates are key industrial fertilisers, and fertiliser nitrates are key pollutants in the eutrophication of water systems.
the general surface wind circulation associated with the high-pressure center (h) is most likely
user
A high-pressure area, high ,or anticyclone.
assistant
how is it formed?
user
Winds within high-pressure areas flow outward from the higher pressure areas near their centers towards the lower pressure areas further from their centers. Gravity adds to the forces. The winds are further twisted due to Coriolis effect.
assistant
could i know more about the effect mentioned above?
user
This is an apparent, but fictitious, force that arises when an observer is in a rotating reference frame, due to the conservation of angular momentum of the air as it moves towards or away from the Earth's axis of rotation.
assistant
how is it related to the wind conditions?
user
They are associated with light winds at the surface and subsidence through the lower portion of the troposphere.
assistant
what is the last term used above?
user
It is the lowest layer of earth's atmosphere.
assistant
what does it consist of?
user
Nitrogrn, oxygen, argon, carbon dioxide and small amounts of other gases.
assistant
who discovered the former from the list above?
user
Daniel Rutherford.
assistant
what are its properties?
user
It has seven electrons and one of the highest electronegativities among the elements.
assistant
what are its uses?
user
A nitrogen atom has seven electrons. In the ground state, they are arranged in the electron configuration 1s2s2p2p2p. It therefore has five valence electrons in the 2s and 2p orbitals, three of which (the p-electrons) are unpaired. It has one of the highest electronegativities among the elements (3.04 on the Pauling scale), exceeded only by chlorine (3.16), oxygen (3.44), and fluorine (3.98). (The light noble gases, helium, neon, and argon, would presumably also be more electronegative, and in fact are on the Allen scale.) Following periodic trends, its single-bond covalent radius of 71 pm is smaller than those of boron (84 pm) and carbon (76 pm), while it is larger than those of oxygen (66 pm) and fluorine (57 pm).
Nitrogen | Atomic
It also results in very large electrostatic forces of attraction between the nucleus and the valence electrons in the 2s and 2p shells, resulting in very high electronegativities. Hypervalency is almost unknown in the 2p elements for the same reason, because the high electronegativity makes it difficult for a small nitrogen atom to be a central atom in an electron-rich three-center four-electron bond since it would tend to attract the electrons strongly to itself. Thus, despite nitrogen's position at the head of group 15 in the periodic table, its chemistry shows huge differences from that of its heavier congeners phosphorus, arsenic, antimony, and bismuth.
Nitrogen | Atomic
Nitrogen is a colourless, odourless, and relatively inert diatomic gas with a density of 1.251 × 10 g/cm (marginally heavier than air). It condenses to a colourless liquid at −195.795 °C and freezes into an ice- or snow-like solid at −210.00 °C. The solid form (density 0.85 g/cm; cf. lithium 0.534) has a hexagonal crystalline structure and is soft and easily crushed. Nitrogen is an insulator in all of its forms. It has a high ionisation energy (1402.3 kJ/mol), low electron affinity (–6.75 kJ/mol), and high electronegativity (3.04). The latter property manifests in the capacity of nitrogen to form usually strong hydrogen bonds, and its preference for forming complexes with metals having low electronegativities, small cationic radii, and often high charges (+3 or more).
Nonmetal | Group 15
Nitrogen may be usefully compared to its horizontal neighbours carbon and oxygen as well as its vertical neighbours in the pnictogen column, phosphorus, arsenic, antimony, and bismuth. Although each period 2 element from lithium to oxygen shows some similarities to the period 3 element in the next group (from magnesium to chlorine; these are known as diagonal relationships), their degree drops off abruptly past the boron–silicon pair. The similarities of nitrogen to sulfur are mostly limited to sulfur nitride ring compounds when both elements are the only ones present.
Nitrogen | Atomic
The nitride anion, N, is much larger at 146 pm, similar to that of the oxide (O: 140 pm) and fluoride (F: 133 pm) anions. The first three ionisation energies of nitrogen are 1.402, 2.856, and 4.577 MJ·mol, and the sum of the fourth and fifth is 16.920 MJ·mol. Due to these very high figures, nitrogen has no simple cationic chemistry. The lack of radial nodes in the 2p subshell is directly responsible for many of the anomalous properties of the first row of the p-block, especially in nitrogen, oxygen, and fluorine. The 2p subshell is very small and has a very similar radius to the 2s shell, facilitating orbital hybridisation.
Nitrogen | Atomic
Atomic nitrogen, also known as active nitrogen, is highly reactive, being a triradical with three unpaired electrons. Free nitrogen atoms easily react with most elements to form nitrides, and even when two free nitrogen atoms collide to produce an excited N molecule, 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.
Nitrogen | Allotropes
The nitrogen-vacancy center is a point defect in the diamond lattice. It consists of a nearest-neighbor pair of a nitrogen atom, which substitutes for a carbon atom, and a lattice vacancy. Two charge states of this defect, neutral N-V and negative N-V, are known from spectroscopic studies using optical absorption, photoluminescence (PL), electron paramagnetic resonance (EPR) and optically detected magnetic resonance (ODMR), which can be viewed as a hybrid of PL and EPR; most details of the structure originate from EPR. A nitrogen atom has five valence electrons. Three of them covalently bond to the carbon atoms and two remain non-bonded and are called a lone pair.
Nitrogen-vacancy center | Structure
The difference in bond energy varies from 0.83 eV per atom in nitrogen gas to 4.94 eV per atom, so having a difference in energy of over 4 eV per atom. This cubic-gauche nitrogen is the highest energy non-nuclear material and is being investigated for use in explosives and rocket fuel. Its energy density is 33 kJ g which is over three times the energy density of HMX. cg-N has all bonds the same length of 1.346 Å at 115 GPa. The cubic-gauche structure for nitrogen is predicted to have bond lengths of 1.40 Å, bond angles of 114.0° and dihedral angles of −106.8°.
Solid nitrogen | Cubic gauche
Under pressures higher than 110 GPa and temperatures around 2000 K nitrogen forms a network solid, bound by single covalent bonds in what is called a cubic-gauche structure, abbreviated as cg-N. This substance is very stiff with a bulk modulus around 298 GPa, similar to diamond. It is very high-energy. The cubic-gauche form has space group "I"23. The unit cell edge is 3.805 Å. There are eight nitrogen atoms per unit cell. The bond angles are very close to tetrahedral. The structure contains rings of nitrogen atoms that are fused together. The position of the lone pairs of electrons is ranged so that their overlap is minimised.
Solid nitrogen | Cubic gauche
Nitrogen is a poor oxidising agent (N + 6"e" → 2NH = −0.057 V at pH 0). Only when it is in a positive oxidation state, that is, in combination with oxygen or fluorine, are its compounds good oxidising agents, for example, 2NO → N = 1.25 V. Its chemistry is largely covalent in nature; anion formation is energetically unfavourable owing to strong inter electron repulsions associated with having three unpaired electrons in its outer valence shell, hence its negative electron affinity. The common oxide of nitrogen (NO) is weakly acidic. Many compounds of nitrogen are less stable than diatomic nitrogen, so nitrogen atoms in compounds seek to recombine if possible and release energy and nitrogen gas in the process, which can be leveraged for explosive purposes.
Nonmetal | Group 15
Nitrogen is the chemical element with atomic number 7, the symbol N and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere. The element nitrogen was discovered as a separable component of air, by Scottish physician Daniel Rutherford, in 1772. It occurs naturally in form of two isotopes: nitrogen-14 and nitrogen-15. Many industrially important compounds, such as ammonia, nitric acid, organic nitrates (propellants and explosives), and cyanides, contain nitrogen. The extremely strong bond in elemental nitrogen dominates nitrogen chemistry, causing difficulty for both organisms and industry in breaking the bond to convert the molecule into useful compounds, but at the same time causing release of large amounts of often useful energy when the compounds burn, explode, or decay back into nitrogen gas.
Period 2 element | Nitrogen
Nitrogen is the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at about seventh in total abundance in the Milky Way and the Solar System. At standard temperature and pressure, two atoms of the element bind to form dinitrogen, a colourless and odorless diatomic gas with the formula N. Dinitrogen forms about 78% of Earth's atmosphere, making it the most abundant uncombined element. Nitrogen occurs in all organisms, primarily in amino acids (and thus proteins), in the nucleic acids (DNA and RNA) and in the energy transfer molecule adenosine triphosphate.
Nitrogen | Introduction
The physical properties of N are quite different from other nuclei. Its properties along with several common nuclei are summarized in the below table.
Nitrogen-15 nuclear magnetic resonance spectroscopy | Physical properties
The human body contains about 3% nitrogen by mass, the fourth most abundant element in the body after oxygen, carbon, and hydrogen. The nitrogen cycle describes movement of the element from the air, into the biosphere and organic compounds, then back into the atmosphere. Many industrially important compounds, such as ammonia, nitric acid, organic nitrates (propellants and explosives), and cyanides, contain nitrogen. The extremely strong triple bond in elemental nitrogen (N≡N), the second strongest bond in any diatomic molecule after carbon monoxide (CO), dominates nitrogen chemistry. This causes difficulty for both organisms and industry in converting N into useful compounds, but at the same time means that burning, exploding, or decomposing nitrogen compounds to form nitrogen gas releases large amounts of often useful energy.
Nitrogen | Introduction
This stands in contrast to the well-characterised cationic and anionic polynitrogens azide (), pentazenium (), and pentazolide (cyclic aromatic ). Under extremely high pressures (1.1 million atm) and high temperatures (2000 K), as produced in a diamond anvil cell, nitrogen polymerises into the single-bonded cubic gauche crystal structure. This structure is similar to that of diamond, and both have extremely strong covalent bonds, resulting in its nickname "nitrogen diamond". At atmospheric pressure, molecular nitrogen condenses (liquefies) at 77 K (−195.79 °C) and freezes at 63 K (−210.01 °C) into the beta hexagonal close-packed crystal allotropic form. Below 35.4 K (−237.6 °C) nitrogen assumes the cubic crystal allotropic form (called the alpha phase).
Nitrogen | Allotropes
The nitrogen rule states that organic compounds containing exclusively hydrogen, carbon, nitrogen, oxygen, silicon, phosphorus, sulfur, and the halogens either have 1) an "odd nominal mass" that indicates an "odd number" of nitrogen atoms are present or 2) an "even nominal mass" that indicates an "even number" of nitrogen atoms in the molecular formula of the molecular ion. The nitrogen rule is not a rule, "per se", as much as a general principle which may prove useful when attempting to solve organic mass spectrometry structures.
Nitrogen rule | Introduction
Nitrogen is the chemical element with the 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 ἀζωτικός "no life", as it is an asphyxiant gas; this name is instead used in many languages, such as French, Italian, Russian, Romanian and Turkish, and appears in the English names of some nitrogen compounds such as hydrazine, azides and azo compounds.
Nitrogen | Introduction
In the simplest case, the linear N–H molecule (imidogen) has its nitrogen atom sp hybridized, with two of its four non-bonded electrons as a lone pair in an sp orbital and the other two occupying a degenerate pair of p orbitals. The electron configuration is consistent with Hund's rule: the low energy form is a triplet with one electron in each of the p orbitals and the high energy form is the singlet with an electron pair filling one p orbital and the other p orbital vacant. As with carbenes, a strong correlation exists between the spin density on the nitrogen atom which can be calculated in silico and the zero-field splitting parameter "D" which can be derived experimentally from electron spin resonance.
Nitrene | Electron configuration
The ammonia molecule has a trigonal pyramidal shape as predicted by the valence shell electron pair repulsion theory (VSEPR theory) with an experimentally determined bond angle of 106.7°. The central nitrogen atom has five outer electrons with an additional electron from each hydrogen atom. This gives a total of eight electrons, or four electron pairs that are arranged tetrahedrally. Three of these electron pairs are used as bond pairs, which leaves one lone pair of electrons. The lone pair repels more strongly than bond pairs, therefore the bond angle is not 109.5°, as expected for a regular tetrahedral arrangement, but 106.7°.
Ammonia | Structure
A nitrogen-vacancy center (N-V center or NV center ) is one of numerous point defects in diamond. Its most explored and useful property is photoluminescence, which can be easily detected from an individual N-V center, especially those in the negative charge state (N-V). Electron spins at N-V centers, localized at atomic scales, can be manipulated at room temperature by applying a magnetic field, electric field, microwave radiation or light, or a combination, resulting in sharp resonances in the intensity and wavelength of the photoluminescence. These resonances can be explained in terms of electron spin related phenomena such as quantum entanglement, spin-orbit interaction and Rabi oscillations, and analysed using advanced quantum optics theory.
Nitrogen-vacancy center | Introduction
It reacts with oxygen to give brown nitrogen dioxide and with halogens to give nitrosyl halides. It also reacts with transition metal compounds to give nitrosyl complexes, most of which are deeply coloured.
Nitrogen | Oxides
This rule is derived from the fact that, perhaps coincidentally, for the most 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 separate covalent bond for the purposes of the calculation).
Nitrogen rule | Formulation of the rule
The diatomic character of the N molecule is retained after liquefaction. The weak van der Waals interaction between the N molecules results in little interatomic interaction, manifested in its very low boiling point. The temperature of liquid nitrogen can readily be reduced to its freezing point by placing it in a vacuum chamber pumped by a vacuum pump. Liquid nitrogen's efficiency as a coolant is limited by the fact that it boils immediately on contact with a warmer object, enveloping the object in insulating nitrogen gas. This effect, known as the Leidenfrost effect, applies to any liquid in contact with an object significantly hotter than its boiling point.
Liquid nitrogen | Physical properties
A carbon–nitrogen bond is a covalent bond between carbon and nitrogen and is one of the most abundant bonds in organic chemistry and biochemistry. Nitrogen has five valence electrons and in simple amines it is trivalent, with the two remaining electrons forming a lone pair. Through that pair, nitrogen can form an additional bond to hydrogen making it tetravalent and with a positive charge in ammonium salts. Many nitrogen compounds can thus be potentially basic but its degree depends on the configuration: the nitrogen atom in amides is not basic due to delocalization of the lone pair into a double bond and in pyrrole the lone pair is part of an aromatic sextet.
Carbon–nitrogen bond | Introduction
There are two possible structures for hydrogen cyanide, HCN and CNH, differing only as to the position of the hydrogen atom. The structure with hydrogen attached to nitrogen, CNH, leads to formal charges of -1 on carbon and +1 on nitrogen, which would be partially compensated for by the electronegativity of nitrogen and Pauling calculated the net charges on H, N and C as -0.79, +0.75 and +0.04 respectively. In contrast the structure with hydrogen bonded to carbon, HCN, has formal charges on carbon and nitrogen of 0, and the effect of the electronegativity of the nitrogen would make the charges on H, C and N +0.04, +0.17 and -0.21.
Pauling's principle of electroneutrality | Explanation of the structure adopted by hydrogen cyanide
Nitrogen bonds to almost all the elements in the periodic table except the first three noble gases, helium, neon, and argon, and some of the very short-lived elements after bismuth, creating an immense variety of binary compounds with varying properties and applications. Many binary compounds are known: with the exception of the nitrogen hydrides, oxides, and fluorides, these are typically called nitrides. Many stoichiometric phases are usually present for most elements (e.g. MnN, MnN, MnN, MnN, MnN, and MnN for 9.2 < "x" < 25.3). They may be classified as "salt-like" (mostly ionic), covalent, "diamond-like", and metallic (or interstitial), although this classification has limitations generally stemming from the continuity of bonding types instead of the discrete and separate types that it implies.
Nitrogen | Nitrides, azides, and nitrido complexes
Nitrogen-containing explosophores (groups I, II and II below) are particularly strong because in addition to providing oxygen they react to form molecular nitrogen, which is a very stable molecule, and thus the overall reaction is strongly exothermic. The gas formed also expands, causing the shock wave which is observed.
Explosophore | Properties
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 component of nucleic acids, amino acids and thus proteins, and the energy-carrying molecule adenosine triphosphate and is thus vital to all life on Earth.
Nitrogen | Organic nitrogen compounds
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 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.
Nitrogen | Allotropes
Above 69 GPa ε-N transforms to an orthorhombic phase designated by ζ-N with a 6% reduction in volume. The space group of ζ-N is "P"222. The lattice constants are a=4.159 Å, b=2.765 Å, c=5.039 Å with eight atoms per unit cell. At 80 GPa the distance between nitrogen atoms in the molecules is 0.982 Å, but the closest distance to other nitrogen atoms is 1.93 Å. As the pressure increases to 138 GPa the bond in the molecules actually lengthens to 1.002 Å while intermolecular distances shorten.
Solid nitrogen | ζ
Molecular nitrogen is the gas form of nitrogen in the atmosphere. The chemical structure for nitrogen gas is N.
Ammoniacal nitrogen | Molecular nitrogen
Another commonly used gas is a dry nitrogen.
Dielectric gas | Introduction
A ζ-N phase compressed to 95 GPa and then heated to over 600 K produces a new structure called θ nitrogen which has a uniform translucent appearance.
Solid nitrogen | θ
Nitrogen sublimes and eventually erupts through holes in the upper layer, carrying dust along with it and creating dark streaks.
Solid nitrogen | Natural occurrence
The nitrogen molecules are randomly tipped at an angle of 55° from the c-axis. There is a strong quadrupole-quadrupole interaction between the molecules.
Solid nitrogen | β
This is in contrast to carbon containing compounds which have lower energies of formation for an equivalent number of single or double bonds than for a C≡C triple bond, allowing for the thermodynamically favorable formation of polymers. It is for this reason that the only allotropic form of nitrogen found in nature is molecular nitrogen () and why novel strategies of synthesizing polynitrogen allotropes in a cost-efficient manner are so highly sought after.
Tetranitrogen | Applications
Solid nitrogen is normally made in a laboratory by evaporating liquid nitrogen in a vacuum. The solid produced is porous.
Solid nitrogen | Introduction
Mo is replaced by V or Fe in vanadium nitrogenase and iron-only nitrogenase respectively. During catalysis, electrons flow from a pair of ATP molecules within Component II to the Fe-S cluster, to the P-cluster, and finally to the FeMo-co, where reduction of N to NH takes place.
Nitrogenase | General mechanism
Solid nitrogen is the solid form of the element nitrogen. It is an important component of the surfaces of Pluto and outer moons of the Solar System such as Neptune's Triton. Under low or moderate pressure solid nitrogen contains dinitrogen molecules held together by London dispersion forces. Non-molecular forms of solid nitrogen produced by extreme pressures have a higher energy density than any other non-nuclear material. Solid nitrogen was first made in 1884, by first liquefying hydrogen with evaporating liquid nitrogen, and then allowing the liquid hydrogen to freeze the nitrogen. Karol Olszewski achieved a world record lowest temperature in 1884 by evaporating vapour from solid nitrogen getting down to 48 K.
Solid nitrogen | Introduction
The nitronate has two different resonance structures, one with a negative charge on the α-carbon and a double bond between the nitrogen and one of the oxygens, and another resonance structure with a double bond between the nitrogen and the α carbon, and no double bond between the nitrogen and the oxygens.
Nitronate | Introduction
Nitrogen trifluoride is the inorganic compound with the formula NF. This nitrogen-fluorine compound is a colorless, nonflammable gas with a slightly musty odor. It finds increasing use as an etchant in microelectronics. Nitrogen trifluoride is an extremely strong greenhouse gas.
Nitrogen trifluoride | Introduction
Both nitrogen and oxygen atoms carry a lone pair of electrons. Therefore, the nitrite ion is a Lewis base.
Nitrite | Structure
Nitrogen dioxide is a reddish-brown gas above with a pungent, acrid odor, becomes a yellowish-brown liquid below , and converts to the colorless dinitrogen tetroxide () below . The bond length between the nitrogen atom and the oxygen atom is 119.7 pm. This bond length is consistent with a bond order between one and two. Unlike ozone, O, the ground electronic state of nitrogen dioxide is a doublet state, since nitrogen has one unpaired electron, which decreases the alpha effect compared with nitrite and creates a weak bonding interaction with the oxygen lone pairs. The lone electron in also means that this compound is a free radical, so the formula for nitrogen dioxide is often written as .
Nitrogen dioxide | Properties
The nitronium ion, , is a cation. It is an onium ion because of its tetravalent nitrogen atom and +1 charge, similar in that regard to ammonium. It is created by the removal of an electron from the paramagnetic nitrogen dioxide molecule, or the protonation of nitric acid (with removal of HO). It is stable enough to exist in normal conditions, but it is generally reactive and used extensively as an electrophile in the nitration of other substances. The ion is generated "in situ" for this purpose by mixing concentrated sulfuric acid and concentrated nitric acid according to the equilibrium:
Nitronium ion | Introduction
This can be achieved by applying external voltage to a p-n junction made from doped diamond, e.g., in a Schottky diode.
Nitrogen-vacancy center | Structure
An individual N-V center can be viewed as a basic unit of a quantum computer, and it has potential applications in novel, more efficient fields of electronics and computational science including quantum cryptography, spintronics, and masers.
Nitrogen-vacancy center | Introduction
This is expected to be a similar configuration for , disproving a proposed tetrahedral (T) model in which all of the nitrogen atoms are equivalent.
Tetranitrogen | Characteristics
Solid nitrogen is used in a slush mixture with liquid nitrogen in order to cool faster than with liquid nitrogen alone, useful for applications such as sperm cryopreservation. The semi-solid mixture can also be called slush nitrogen or SN2. 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 | Use
However, the hydrogen bonding in NH is weaker than that in HO due to the lower electronegativity of nitrogen compared to oxygen and the presence of only one lone pair in NH rather than two in HO. It is a weak base in aqueous solution (p"K" 4.74); its conjugate acid is ammonium, . It can also act as an extremely weak acid, losing a proton to produce the amide anion, . It thus undergoes self-dissociation, similar to water, to produce ammonium and amide. Ammonia burns in air or oxygen, though not readily, to produce nitrogen gas; it burns in fluorine with a greenish-yellow flame to give nitrogen trifluoride.
Nitrogen | Hydrides
Biologically mediated reactions (e.g., assimilation, nitrification, and denitrification) strongly control nitrogen dynamics in the soil. These reactions typically result in N enrichment of the substrate and depletion of the product. The heavy isotope N was first discovered by S. M. Naudé in 1929, soon after heavy isotopes of the neighbouring elements oxygen and carbon were discovered. It presents one of the lowest thermal neutron capture cross-sections of all isotopes. It is frequently used in nuclear magnetic resonance (NMR) spectroscopy to determine the structures of nitrogen-containing molecules, due to its fractional nuclear spin of one-half, which offers advantages for NMR such as narrower line width.
Nitrogen | Isotopes
With dideuterium, a clathrate (N)D exits around 70 GPa.
Solid nitrogen | Hydrogen
The nitrogen rule states that organic molecules that contain hydrogen, carbon, nitrogen, oxygen, silicon, phosphorus, sulfur, and the halogens have an odd nominal mass if they have an odd number of nitrogen atoms or an even mass if they have an even number of nitrogen atoms are present. The nitrogen rule is true for 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 separate covalent bond.
Mass spectral interpretation | Nitrogen rule
For a NF molecule to form, five fluorine atoms have to be arranged around a nitrogen atom. There is insufficient space to do this in the most compact way, so that bond lengths are forced to be longer. Calculations show that the NF molecule is thermodynamically favourably inclined to form NF and F radicals with energy 36 kJ/mol and a transition barrier around 67–84 kJ/mol. Nitrogen pentafluoride also violates the octet rule in which compounds with eight outer shell electrons are particularly stable.
Nitrogen pentafluoride | Molecule
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.
Nitrogen | Production
exists in equilibrium with the colourless gas dinitrogen tetroxide (): The equilibrium is characterized by , which is exothermic. NO is favored at higher temperatures, while at lower temperatures, dinitrogen tetroxide (NO) predominates. Dinitrogen tetroxide () can be obtained as a white solid with melting point −11.2 °C. NO is paramagnetic due to its unpaired electron, while NO is diamagnetic. The chemistry of nitrogen dioxide has been investigated extensively. At 150 °C, decomposes with release of oxygen via an endothermic process ():
Nitrogen dioxide | Basic thermal properties
There are 3 main forms of nitrogen:
Ammoniacal nitrogen | Ammonia and mineral forms of Nitrogen
The nitrogen rule states that organic compounds containing exclusively hydrogen, carbon, nitrogen, oxygen, silicon, phosphorus, sulfur, and the halogens either have an odd nominal mass that indicates an odd number of nitrogen atoms are present or an even nominal mass that indicates an even number of nitrogen atoms are present in the molecular ion.
Mass (mass spectrometry) | Nitrogen rule
Nitrogen is one of the most important elements in organic chemistry. Many organic functional groups involve a carbon–nitrogen bond, such as amides (RCONR), amines (RN), imines (RC(=NR)R), imides (RCO)NR, azides (RN), azo compounds (RNR), cyanates and isocyanates (ROCN or RCNO), nitrates (RONO), nitriles and isonitriles (RCN or RNC), nitrites (RONO), nitro compounds (RNO), nitroso compounds (RNO), oximes (RCR=NOH), and pyridine derivatives. C–N bonds are strongly polarised towards nitrogen. In these compounds, nitrogen is usually trivalent (though it can be tetravalent in quaternary ammonium salts, RN), with a lone pair that can confer basicity on the compound by being coordinated to a proton.
Nitrogen | Organic nitrogen compounds
Nr is removed from the biosphere via Denitrification.
Reactive nitrogen | Introduction
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 oxygen, and specially purified grades containing at most 2 ppm oxygen and 10 ppm argon are also available.
Nitrogen | Production
Nitrogen-13 (N) is a radioisotope of nitrogen used in positron emission tomography (PET). It has a half-life of a little under ten minutes, so it must be made at the PET site. A cyclotron may be used for this purpose. Nitrogen-13 is used to tag ammonia molecules for PET myocardial perfusion imaging.
Nitrogen-13 | Introduction
In particular, since the B–N unit is isoelectronic to C–C, and carbon is essentially intermediate in size between boron and nitrogen, much of organic chemistry finds an echo in boron–nitrogen chemistry, such as in borazine ("inorganic benzene"). Nevertheless, the analogy is not exact due to the ease of nucleophilic attack at boron due to its deficiency in electrons, which is not possible in a wholly carbon-containing ring. The largest category of nitrides are the interstitial nitrides of formulae MN, MN, and MN (although variable composition is perfectly possible), where the small nitrogen atoms are positioned in the gaps in a metallic cubic or hexagonal close-packed lattice.
Nitrogen | Nitrides, azides, and nitrido complexes
As quoted at http://www.webelements.com/ from these sources:
Electronegativities of the elements (data page) | WEL
It is formed by catalytic oxidation of ammonia. It is a colourless paramagnetic gas that, being thermodynamically unstable, decomposes to nitrogen and oxygen gas at 1100–1200 °C. Its bonding is similar to that in nitrogen, but one extra electron is added to a "π"* antibonding orbital and thus the bond order has been reduced to approximately 2.5; hence dimerisation to O=N–N=O is unfavourable except below the boiling point (where the "cis" isomer is more stable) because it does not actually increase the total bond order and because the unpaired electron is delocalised across the NO molecule, granting it stability. There is also evidence for the asymmetric red dimer O=N–O=N when nitric oxide is condensed with polar molecules.
Nitrogen | Oxides
Nitrogen-15 is a rare stable isotope of nitrogen. Two sources of nitrogen-15 are the positron emission of oxygen-15 and the beta decay of carbon-15. Nitrogen-15 presents one of the lowest thermal neutron capture cross sections of all isotopes. Nitrogen-15 is frequently used in NMR (Nitrogen-15 NMR spectroscopy). Unlike the more abundant nitrogen-14, which has an integer nuclear spin and thus a quadrupole moment, N has a fractional nuclear spin of one-half, which offers advantages for NMR such as narrower line width. Nitrogen-15 tracing is a technique used to study the nitrogen cycle.
Isotopes of nitrogen | Nitrogen-15
The nitrogen cycle make extensive use of metals for the redox interconversions.
Bioinorganic chemistry | Enzymology
Nitrogen dioxide is a 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 for use primarily in the production of fertilizers. At higher temperatures it is a reddish-brown gas. Nitrogen dioxide is a paramagnetic, bent molecule with C point group symmetry.
Nitrogen dioxide | Introduction
However, if the nitrogen-14 (N) nucleus was composed of 14 protons and 7 electrons, an odd number of spin-1/2 particles, then the resultant nuclear spin should be half-integer. Kronig therefore suggested that perhaps "protons and electrons do not retain their identity to the extent they do outside the nucleus".
Discovery of the neutron | Problems of the nuclear electrons hypothesis
This effect has been most clearly observed on Pluto (by the "New Horizons" space probe in 2015), where water ice makes up a major part of the surface layers as icebergs on top of nitrogen ice. Solid nitrogen mixes with solid carbon monoxide and methane on the surface of Pluto. The thermal conductivity of solid nitrogen is 0.7 W m K. Thermal conductivity varies with temperature and the relation is given by "k" = 180.2×T watts per kelvin. Specific heat is given by 926.91×e joules per kilogram per kelvin. Its appearance at 50 K is transparent, while at 20 K it is white.
Solid nitrogen | Bulk properties
The vacancy has three unpaired electrons. Two of them make a quasi covalent bond and one remains unpaired. The overall symmetry, however, is axial (trigonal C); one can visualize this by imagining the three unpaired vacancy electrons continuously exchanging their roles. The N-V thus has one unpaired electron and is paramagnetic. However, despite extensive efforts, electron paramagnetic resonance signals from N-V avoided detection for decades until 2008. Optical excitation is required to bring the N-V defect into the EPR-detectable excited state; the signals from the ground state are presumably too broad for EPR detection. The N-V centers can be converted into N-V by changing the Fermi level position.
Nitrogen-vacancy center | Structure
ABC transporters). To do this, his group uses X-ray crystallography. His interest in nitrogenase began in William Lipscomb's laboratory.
Douglas C. Rees | Introduction
The lone electron pair on the nitrogen atom (N) in ammonia, represented as a line above the N, forms the bond with a proton (H). Thereafter, all four N–H bonds are equivalent, being polar covalent bonds. The ion has a tetrahedral structure and is isoelectronic with methane and borohydride. In terms of size, the ammonium cation ("r" = 175 pm) resembles the caesium cation ("r" = 183 pm).
Ammonium | Structure and bonding
The boundary of the molecule appears at an electron density of 0.0135 eÅ. The molecules line up in rows end to end diagonally on the ab plane. These rows stack side by side with molecules offset by half their length to form layers in the (001) plane, perpendicular to the c-axis. Layers stack on top of each other each rotated by 90° compared to the plane below. Coordinates of atoms in the unit cell are given by (x,x,0),(-x,-x,0),(+x,-x,),(-x,+x,) with x=r/a and r=interatomic distance in nitrogen molecule, = 1.10 Å. (unit cell dimension as above a=3.957 Å). The molecules can vibrate up to 10° on the ab plane, and up to 15° in the direction of the c axis.
Solid nitrogen | γ
Because the nitrogen atoms have five available electrons (one more than the carbon atoms they replace), they act as "deep donors"; that is, each substituting nitrogen has an extra electron to donate and forms a donor energy level within the band gap. Light with energy above ~2.2 eV can excite the donor electrons into the conduction band, resulting in the yellow color. The C center produces a characteristic infrared absorption spectrum with a sharp peak at 1344 cm and a broader feature at 1130 cm. Absorption at those peaks is routinely used to measure the concentration of single nitrogen. Another proposed way, using the UV absorption at ~260 nm, has later been discarded as unreliable.
Crystallographic defects in diamond | C-nitrogen center
The familiar Pauling electronegativity scale relies upon chemical bond energies, but such values have obviously not been measured for inert helium and neon. The Allen electronegativity scale, which relies only upon (measurable) atomic energies, identifies neon as the most electronegative element, closely followed by fluorine and helium.
Neon | Chemistry
When the pressure on He(N) exceeds 135 GPa the substance changes from clear to black, and takes on an amorphous form similar to η-N.
Solid nitrogen | Helium
The transfer of four equivalents are required before the productive addition of N, although reaction of E with N is also possible. Notably, nitrogen reduction has been shown to require 8 equivalents of protons and electrons as opposed to the 6 equivalents predicted by the balanced chemical reaction.
Nitrogenase | Lowe-Thorneley kinetic model
A hydroxide ligand on the six coordinate Ni is deprotonated by a base. The carbonyl carbon is subsequently attacked by the electronegative oxygen. A pair of electrons from the nitrogen-carbon double bond returns to the nitrogen and neutralizes the charge on it, while the now 4-coordinate carbon assumes an intermediate tetrahedral orientation. The breakdown of this intermediate is then helped by a sulfhydryl group of a cysteine located near the active site. A hydrogen bonds to one of the nitrogen atoms, breaking its bond with carbon, and releasing an NH3 molecule. Simultaneously, the bond between the oxygen and the 6-coordinate nickel is broken.
Urease | Blakeley/Zerner
Faster cooling may be obtained by plunging an object into a slush of liquid and solid nitrogen rather than liquid nitrogen alone.
Liquid nitrogen | Physical properties
Nitrogen occurs in all living organisms, and the nitrogen cycle describes movement of the element from air into the biosphere and organic compounds, then back into the atmosphere. Synthetically produced nitrates are key ingredients of industrial fertilizers, and also key pollutants in causing the eutrophication of water systems. Nitrogen is a constituent element of amino acids and thus of proteins, and of nucleic acids (DNA and RNA). It resides in the chemical structure of almost all neurotransmitters, and is a defining component of alkaloids, biological molecules produced by many organisms.
Period 2 element | Nitrogen
This adduct was first reported by Bernard Courtois in 1812, and its formula was finally determined in 1905 by Oswald Silberrad. Its solid state structure consists of chains of -NI-I-NI-I-NI-I-... Ammonia molecules are situated between the chains. When kept cold in the dark and damp with ammonia, NI · NH is stable.
Nitrogen triiodide | Structure of NI and its derivatives
The molecule is nonplanar. All nitrogen centers are at least somewhat pyramidal, indicative of weaker C-N pi-bonding. The C-N and C-O distances are about 1.36 and 1.25 Å, respectively.
Carbohydrazide | Structure
Neon or xenon atoms can also be included in solid nitrogen in the β and δ phases. Inclusion of neon pushes the β−δ phase boundary to higher pressures. Argon is also very miscible in solid nitrogen. For compositions of argon and nitrogen with 60% to 70% nitrogen, the hexagonal form remains stable to 0 K. A van der Waals compound of xenon and nitrogen exists above 5.3 GPa. A van der Waals compound of neon and nitrogen was shown using Raman spectroscopy. The compound has formula (N)Ne. It has a hexagonal structure, with a=14.400 c=8.0940 at a pressure of 8 GPa.
Solid nitrogen | Noble gases
Spectroscopic characterization of these intermediates has allowed for greater understanding of nitrogen reduction by nitrogenase, however, the mechanism remains an active area of research and debate. Briefly listed below are spectroscopic experiments for the intermediates before the addition of nitrogen: E – This is the resting state of the enzyme before catalysis begins. EPR characterization shows that this species has a spin of /. E – The one electron reduced intermediate has been trapped during turnover under N. Mӧssbauer spectroscopy of the trapped intermediate indicates that the FeMo-co is integer spin greater than 1.
Nitrogenase | Intermediates E through E
For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used. The electron configuration can be visualized as the core electrons, equivalent to the noble gas of the preceding period, and the valence electrons: each element in a period differs only by the last few subshells. Phosphorus, for instance, is in the third period. It differs from the second-period neon, whose configuration is 1s 2s 2p, only by the presence of a third shell. The portion of its configuration that is equivalent to neon is abbreviated as [Ne], allowing the configuration of phosphorus to be written as [Ne] 3s 3p rather than writing out the details of the configuration of neon explicitly.
Electron configuration | Notation
A robust frequency-modulated radio receiver using the electron-spin-dependent photoluminescence that operated up to 350 °C demonstrates the possibility for use in extreme conditions.
Nitrogen-vacancy center | Potential applications
In atmospheric chemistry:
Nitrogen oxide | Atmospheric sciences
BN nanosheets consist of sp-conjugated boron and nitrogen atoms that form a honeycomb structure. They contain two different edges: armchair and zig-zag. The armchair edge consists of either boron or nitrogen atoms, while the zig-zag edge consists of alternating boron and nitrogen atoms. These 2D structures can stack on top of each other and are held by Van der Waals forces to form few-layer boron nitride nanosheets. In these structures, the boron atoms of one sheet are positioned on top or below the nitrogen atoms due to electron-deficient nature of boron and electron-rich nature of nitrogen.
Boron nitride nanosheet | Structure
A neptunium atom has 93 electrons, arranged in the configuration [Rn]5f6d7s. This differs from the configuration expected by the Aufbau principle in that one electron is in the 6d subshell instead of being as expected in the 5f subshell. This is because of the similarity of the electron energies of the 5f, 6d, and 7s subshells. In forming compounds and ions, all the valence electrons may be lost, leaving behind an inert core of inner electrons with the electron configuration of the noble gas radon; more commonly, only some of the valence electrons will be lost. The electron configuration for the tripositive ion Np is [Rn] 5f, with the outermost 7s and 6d electrons lost first: this is exactly analogous to neptunium's lanthanide homolog promethium, and conforms to the trend set by the other actinides with their [Rn] 5f electron configurations in the tripositive state.
Neptunium | Atomic
NO is nitrogen dioxide. NO2 or NO may also refer to:
NO2 (disambiguation) | Introduction
Boron behaves as a Lewis acid and nitrogen behaves as a Lewis base.
Borazine | Structure
This process requires constant temperature, close to ambient. With this process, nitrogen is produced by the plant at the above-atmospheric pressure, while the adsorbent regeneration is accomplished at below-atmospheric pressure.
Nitrogen generator | Pressure swing adsorption technology
It is probable that "Natronomonas" uses ferredoxin and not NADH as the electron donor for all three reductive conversions. This is evident from the occurrence of conserved ferredoxin-binding residues within the N. pharaonis NirA protein and ferredoxin dependence of nitrate and nitrite reductases in the halophile "Haloferax mediterranei".
Natronomonas | Cell structure and metabolism
Throughout the 1920s, physicists assumed that the atomic nucleus was composed of protons and "nuclear electrons". Under this hypothesis, the nitrogen-14 (N) nucleus would be composed of 14 protons and 7 electrons, so that it would have a net charge of +7 elementary charge units and a mass of 14 atomic mass units. This nucleus would also be orbited by another 7 electrons, termed "external electrons" by Rutherford, to complete the N atom. However problems with the hypothesis soon became apparent. Ralph Kronig pointed out in 1926 that the observed hyperfine structure of atomic spectra was inconsistent with the proton–electron hypothesis.
Discovery of the neutron | Problems of the nuclear electrons hypothesis
is used as an intermediate in the manufacturing of nitric acid, as a nitrating agent in manufacturing of chemical explosives, as a polymerization inhibitor for acrylates, as a flour bleaching agent., and as a room temperature sterilization agent. It is also used as an oxidizer in rocket fuel, for example in red fuming nitric acid; it was used in the Titan rockets, to launch Project Gemini, in the maneuvering thrusters of the Space Shuttle, and in unmanned space probes sent to various planets.
Nitrogen dioxide | Uses
Solid nitrogen has several properties relevant to its formation of rocks in the outer Solar System. Even at the low temperatures of solid nitrogen it is fairly volatile and can sublime to form an atmosphere, or condense back into nitrogen frost. At 58 K the ultimate compressive strength is 0.24 MPa. Strength increases as temperature lowers becoming 0.54 MPa at 40.6 K. Elastic modulus varies from 161 to 225 MPa over the same range. Compared to other materials, solid nitrogen loses cohesion at low pressures and flows in the form of glaciers when amassed. Yet its density is higher than that of water ice, so the forces of buoyancy will naturally transport blocks of water ice towards the surface.
Solid nitrogen | Bulk properties
Nitrogen pentafluoride is a theoretical compound of nitrogen and fluorine that is hypothesized to exist based on the existence of the pentafluorides of the atoms below nitrogen in the periodic table, such as phosphorus pentafluoride. Theoretical models of the nitrogen pentafluoride (NF) molecule are either a trigonal bipyramidal covalently bound molecule with symmetry group D, or NFF, which would be an ionic solid. Also, a related compound NHF is known.
Nitrogen pentafluoride | Introduction
Then, individual N-V centers can be studied with standard optical microscopes or, better, near-field scanning optical microscopes having sub-micrometre resolution.
Nitrogen-vacancy center | Production
The reaction proceeds as a standard 1,3-dipolar cycloaddition, a type of asynchronous, concerted pericyclic shift. The ambivalent nature of the 1,3-dipole should make the identification of an electrophilic or nucleophilic center on the azide impossible such that the direction of the cyclic electron flow is meaningless. [p] However, computation has shown that the electron distribution amongst nitrogens causes the innermost nitrogen atom to bear the greatest negative charge.
Bioorthogonal chemistry | Mechanism
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.
Nitrogen generator | Adsorption concept