Misplaced Pages

#927072

102-758: Ellery Schempp (born Ellory Schempp , August 5, 1940) is an American physicist and the primary student involved in the landmark 1963 United States Supreme Court decision of Abington School District v. Schempp which declared that required public school sanctioned Bible readings were unconstitutional. Schempp was born in Philadelphia and grew up in the Roslyn community of Abington Township . He graduated from Abington High School in 1958, and attended Tufts University where he earned bachelor degrees in physics and geology . In 1967, Schempp received his Ph.D. in physics from Brown University . In 1977, Schempp

204-514: A dinitrogen complex to be discovered was [Ru(NH 3 ) 5 (N 2 )] (see figure at right), and soon many other such complexes were discovered. These complexes , in which a nitrogen molecule donates at least one lone pair of electrons to a central metal cation, illustrate how N 2 might bind to the metal(s) in nitrogenase and the catalyst for the Haber process : these processes involving dinitrogen activation are vitally important in biology and in

306-700: A master's degree like MSc, MPhil, MPhys or MSci. For research-oriented careers, students work toward a doctoral degree specializing in a particular field. Fields of specialization include experimental and theoretical astrophysics , atomic physics , biological physics , chemical physics , condensed matter physics , cosmology , geophysics , gravitational physics , material science , medical physics , microelectronics , molecular physics , nuclear physics , optics , particle physics , plasma physics , quantum information science , and radiophysics . The three major employers of career physicists are academic institutions, laboratories, and private industries, with

408-473: A bridging ligand, donating all three electron pairs from the triple bond ( μ 3 -N 2 ). A few complexes feature multiple N 2 ligands and some feature N 2 bonded in multiple ways. Since N 2 is isoelectronic with carbon monoxide (CO) and acetylene (C 2 H 2 ), the bonding in dinitrogen complexes is closely allied to that in carbonyl compounds, although N 2 is a weaker σ -donor and π -acceptor than CO. Theoretical studies show that σ donation

510-426: A dilute gas it is less dangerous and is thus used industrially to bleach and sterilise flour. Nitrogen tribromide (NBr 3 ), first prepared in 1975, is a deep red, temperature-sensitive, volatile solid that is explosive even at −100 °C. Nitrogen triiodide (NI 3 ) is still more unstable and was only prepared in 1990. Its adduct with ammonia, which was known earlier, is very shock-sensitive: it can be set off by

612-498: A liquid, it is a very good solvent with a high heat of vaporisation (enabling it to be used in vacuum flasks), that also has a low viscosity and electrical conductivity and high dielectric constant , and is less dense than water. However, the hydrogen bonding in NH 3 is weaker than that in H 2 O due to the lower electronegativity of nitrogen compared to oxygen and the presence of only one lone pair in NH 3 rather than two in H 2 O. It

714-483: A long time, sources of nitrogen compounds were limited. Natural sources originated either from biology or deposits of nitrates produced by atmospheric reactions. Nitrogen fixation by industrial processes like the Frank–Caro process (1895–1899) and Haber–Bosch process (1908–1913) eased this shortage of nitrogen compounds, to the extent that half of global food production now relies on synthetic nitrogen fertilisers. At

816-452: A minimum, the owner must possess a three-year bachelors or equivalent degree in physics or a related field and an additional minimum of six years' experience in a physics-related activity; or an Honor or equivalent degree in physics or a related field and an additional minimum of five years' experience in a physics-related activity; or master or equivalent degree in physics or a related field and an additional minimum of three years' experience in

918-565: A physics-related activity; a Doctorate or equivalent degree in Physics or a related field; or training or experience which, in the opinion of the Council, is equivalent to any of the above. Physicists may be a member of a physical society of a country or region. Physical societies commonly publish scientific journals, organize physics conferences and award prizes for contributions to the field of physics. Some examples of physical societies are

1020-494: A preference for forming multiple bonds, typically with carbon, oxygen, or other nitrogen atoms, through p π –p π interactions. Thus, for example, nitrogen occurs as diatomic molecules and therefore has very much lower melting (−210 °C) and boiling points (−196 °C) than the rest of its group, as the N 2 molecules are only held together by weak van der Waals interactions and there are very few electrons available to create significant instantaneous dipoles. This

1122-591: 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

SECTION 10

#1732802361928

1224-416: A professional practice examination must also be passed. An exemption can be granted to a candidate that has practiced physics for at least seven years and provide a detailed description of their professional accomplishments which clearly demonstrate that the exam is not necessary. Work experience will be considered physics-related if it uses physics directly or significantly uses the modes of thought (such as

1326-470: A promising ceramic if not for the difficulty of working with and sintering it. In particular, the group 13 nitrides, most of which are promising semiconductors , are isoelectronic with graphite, diamond, and silicon carbide and have similar structures: their bonding changes from covalent to partially ionic to metallic as the group is descended. In particular, since the B–N unit is isoelectronic to C–C, and carbon

1428-463: A significant dynamic surface coverage on Pluto and outer moons of the Solar System such as Triton . 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. It is very weak and flows in the form of glaciers, and on Triton geysers of nitrogen gas come from the polar ice cap region. The first example of

1530-606: A very high energy density, that could be used as powerful propellants or explosives. 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

1632-465: Is oxatetrazole (N 4 O), an aromatic ring. Nitrous oxide (N 2 O), better known as laughing gas, is made by thermal decomposition of molten ammonium nitrate at 250 °C. This is a redox reaction and thus nitric oxide and nitrogen are also produced as byproducts. It is mostly used as a propellant and aerating agent for sprayed canned whipped cream , and was formerly commonly used as an anaesthetic. Despite appearances, it cannot be considered to be

1734-439: Is ONF 3 , which has aroused interest due to the short N–O distance implying partial double bonding and the highly polar and long N–F bond. Tetrafluorohydrazine, unlike hydrazine itself, can dissociate at room temperature and above to give the radical NF 2 •. Fluorine azide (FN 3 ) is very explosive and thermally unstable. Dinitrogen difluoride (N 2 F 2 ) exists as thermally interconvertible cis and trans isomers, and

1836-419: Is a fuming, colourless liquid that smells similar to ammonia. Its physical properties are very similar to those of water (melting point 2.0 °C, boiling point 113.5 °C, density 1.00 g/cm ). Despite it being an endothermic compound, it is kinetically stable. It burns quickly and completely in air very exothermically to give nitrogen and water vapour. It is a very useful and versatile reducing agent and

1938-491: Is a more important factor allowing the formation of the M–N bond than π back-donation, which mostly only weakens the N–N bond, and end-on ( η ) donation is more readily accomplished than side-on ( η ) donation. Today, dinitrogen complexes are known for almost all the transition metals , accounting for several hundred compounds. They are normally prepared by three methods: Occasionally

2040-763: Is a popular speaker at Unitarian Universalist and secular humanist meetings, where he speaks about his landmark protest as well as the current state of democracy, the Constitution , and the Bill of Rights . As of 2011, he was still active in the Bedford Unitarian Universalist church near his home. Schempp is a member of the American Humanist Association , the Freedom from Religion Foundation , and Americans United for

2142-467: Is a weak base in aqueous solution ( p K b 4.74); its conjugate acid is ammonium , NH 4 . It can also act as an extremely weak acid, losing a proton to produce the amide anion, NH 2 . 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 . Reactions with

SECTION 20

#1732802361928

2244-401: Is a weak diprotic acid with the structure HON=NOH (p K a1 6.9, p K a2 11.6). Acidic solutions are quite stable but above pH 4 base-catalysed decomposition occurs via [HONNO] to nitrous oxide and the hydroxide anion. Hyponitrites (involving the N 2 O 2 anion) are stable to reducing agents and more commonly act as reducing agents themselves. They are an intermediate step in

2346-399: Is a weaker base than ammonia. It is also commonly used as a rocket fuel. Hydrazine is generally made by reaction of ammonia with alkaline sodium hypochlorite in the presence of gelatin or glue: (The attacks by hydroxide and ammonia may be reversed, thus passing through the intermediate NHCl instead.) The reason for adding gelatin is that it removes metal ions such as Cu that catalyses

2448-612: Is also evidence for the asymmetric red dimer O=N–O=N when nitric oxide is condensed with polar molecules. 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. Blue dinitrogen trioxide (N 2 O 3 ) is only available as a solid because it rapidly dissociates above its melting point to give nitric oxide, nitrogen dioxide (NO 2 ), and dinitrogen tetroxide (N 2 O 4 ). The latter two compounds are somewhat difficult to study individually because of

2550-705: Is based on an intellectual ladder of discoveries and insights from ancient times to the present. Many mathematical and physical ideas used today found their earliest expression in the work of ancient civilizations, such as the Babylonian astronomers and Egyptian engineers , the Greek philosophers of science and mathematicians such as Thales of Miletus , Euclid in Ptolemaic Egypt , Archimedes of Syracuse and Aristarchus of Samos . Roots also emerged in ancient Asian cultures such as India and China, and particularly

2652-404: 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

2754-515: Is known. Industrially, ammonia (NH 3 ) is the most important compound of nitrogen and is prepared in larger amounts than any other compound because it contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilisers. It is a colourless alkaline gas with a characteristic pungent smell. The presence of hydrogen bonding has very significant effects on ammonia, conferring on it its high melting (−78 °C) and boiling (−33 °C) points. As

2856-434: Is mildly toxic in concentrations above 100 mg/kg, but small amounts are often used to cure meat and as a preservative to avoid bacterial spoilage. It is also used to synthesise hydroxylamine and to diazotise primary aromatic amines as follows: Nitrite is also a common ligand that can coordinate in five ways. The most common are nitro (bonded from the nitrogen) and nitrito (bonded from an oxygen). Nitro-nitrito isomerism

2958-629: 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 low level of chemical reactivity. Other nitrogen oligomers and polymers may be possible. If they could be synthesised, they may have potential applications as materials with

3060-489: Is much more common, making up 99.634% of natural nitrogen, and the second (which is slightly heavier) makes up the remaining 0.366%. This leads to an atomic weight of around 14.007 u. Both of these stable isotopes are produced in the CNO cycle in stars , but N is more common as its proton capture is the rate-limiting step. N is one of the five stable odd–odd nuclides (a nuclide having an odd number of protons and neutrons);

3162-682: Is not possible for its vertical neighbours; thus, the nitrogen oxides , nitrites , nitrates , nitro- , nitroso -, azo -, and diazo -compounds, azides , cyanates , thiocyanates , and imino -derivatives find no echo with phosphorus, arsenic, antimony, or bismuth. By the same token, however, the complexity of the phosphorus oxoacids finds no echo with nitrogen. Setting aside their differences, nitrogen and phosphorus form an extensive series of compounds with one another; these have chain, ring, and cage structures. Table of thermal and physical properties of nitrogen (N 2 ) at atmospheric pressure: Nitrogen has two stable isotopes : N and N. The first

Ellery Schempp - Misplaced Pages Continue

3264-660: Is of interest for the preparation of explosives. It is a deliquescent , colourless crystalline solid that is sensitive to light. In the solid state it is ionic with structure [NO 2 ] [NO 3 ] ; as a gas and in solution it is molecular O 2 N–O–NO 2 . Hydration to nitric acid comes readily, as does analogous reaction with hydrogen peroxide giving peroxonitric acid (HOONO 2 ). It is a violent oxidising agent. Gaseous dinitrogen pentoxide decomposes as follows: Many nitrogen oxoacids are known, though most of them are unstable as pure compounds and are known only as aqueous solutions or as salts. Hyponitrous acid (H 2 N 2 O 2 )

3366-521: 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 2 , 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

3468-443: Is produced from O (in water) via an (n,p) reaction , in which the O atom captures a neutron and expels a proton. It has a short half-life of about 7.1 s, but its decay back to O produces high-energy gamma radiation (5 to 7 MeV). Because of this, access to the primary coolant piping in a pressurised water reactor must be restricted during reactor power operation. It is a sensitive and immediate indicator of leaks from

3570-474: Is significant. It is a weak acid with p K a 3.35 at 18 °C. They may be titrimetrically analysed by their oxidation to nitrate by permanganate . They are readily reduced to nitrous oxide and nitric oxide by sulfur dioxide , to hyponitrous acid with tin (II), and to ammonia with hydrogen sulfide . Salts of hydrazinium N 2 H 5 react with nitrous acid to produce azides which further react to give nitrous oxide and nitrogen. Sodium nitrite

3672-482: 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

3774-404: 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). 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

3876-615: Is the Nobel Prize in Physics , awarded since 1901 by the Royal Swedish Academy of Sciences . National physical societies have many prizes and awards for professional recognition. In the case of the American Physical Society , as of 2023, there are 25 separate prizes and 33 separate awards in the field. Chartered Physicist (CPhys) is a chartered status and a professional qualification awarded by

3978-523: Is the most important nitrogen radioisotope, being relatively long-lived enough to use in positron emission tomography (PET), although its half-life is still short and thus it must be produced at the venue of the PET, for example in a cyclotron via proton bombardment of O producing N and an alpha particle . The radioisotope N is the dominant radionuclide in the coolant of pressurised water reactors or boiling water reactors during normal operation. It

4080-400: Is the simplest stable molecule with an odd number of electrons. In mammals, including humans, it is an important cellular signalling molecule involved in many physiological and pathological processes. 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

4182-476: Is the strongest π donor known among ligands (the second-strongest is O ). Nitrido complexes are generally made by the thermal decomposition of azides or by deprotonating ammonia, and they usually involve a terminal {≡N} group. The linear azide anion ( N 3 ), being isoelectronic with nitrous oxide , carbon dioxide , and cyanate , forms many coordination complexes. Further catenation is rare, although N 4 (isoelectronic with carbonate and nitrate )

Ellery Schempp - Misplaced Pages Continue

4284-640: Is thermodynamically stable, and most readily produced by the electrolysis of molten ammonium fluoride dissolved in anhydrous hydrogen fluoride . Like carbon tetrafluoride , it is not at all reactive and is stable in water or dilute aqueous acids or alkalis. Only when heated does it act as a fluorinating agent, and it reacts with copper , arsenic, antimony, and bismuth on contact at high temperatures to give tetrafluorohydrazine (N 2 F 4 ). The cations NF 4 and N 2 F 3 are also known (the latter from reacting tetrafluorohydrazine with strong fluoride-acceptors such as arsenic pentafluoride ), as

4386-506: Is usually produced from air by pressure swing adsorption technology. About 2/3 of commercially produced elemental nitrogen is used as an inert (oxygen-free) gas for commercial uses such as food packaging, and much of the rest is used as liquid nitrogen in cryogenic applications. 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),

4488-569: The American Physical Society , the Institute of Physics , with the oldest physical society being the German Physical Society . Nitrogen Nitrogen is a chemical element ; it has symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table , often called the pnictogens . It is a common element in the universe , estimated at seventh in total abundance in

4590-512: The Greek word άζωτικός (azotikos), "no life", due to it being asphyxiant . In an atmosphere of pure nitrogen, animals died and flames were extinguished. Though Lavoisier's name was not accepted in English since it was pointed out that all gases but oxygen are either asphyxiant or outright toxic, it is used in many languages (French, Italian, Portuguese, Polish, Russian, Albanian, Turkish, etc.;

4692-697: The Institute of Physics . It is denoted by the postnominals "CPhys". Achieving chartered status in any profession denotes to the wider community a high level of specialised subject knowledge and professional competence. According to the Institute of Physics, holders of the award of the Chartered Physicist (CPhys) demonstrate the "highest standards of professionalism, up-to-date expertise, quality and safety" along with "the capacity to undertake independent practice and exercise leadership" as well as "commitment to keep pace with advancing knowledge and with

4794-548: The Islamic medieval period , which saw the development of scientific methodology emphasising experimentation , such as the work of Ibn al-Haytham (Alhazen) in the 11th century. The modern scientific worldview and the bulk of physics education can be said to flow from the scientific revolution in Europe, starting with the work of astronomer Nicolaus Copernicus leading to the physics of Galileo Galilei and Johannes Kepler in

4896-715: The Milky Way and the Solar System . At standard temperature and pressure , two atoms of the element bond to form N 2 , a colourless and odourless diatomic gas . N 2 forms about 78% of Earth's atmosphere , making it the most abundant chemical species in air. Because of the volatility of nitrogen compounds, nitrogen is relatively rare in the solid parts of the Earth. It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772 and independently by Carl Wilhelm Scheele and Henry Cavendish at about

4998-435: The anhydride of hyponitrous acid (H 2 N 2 O 2 ) because that acid is not produced by the dissolution of nitrous oxide in water. It is rather unreactive (not reacting with the halogens, the alkali metals, or ozone at room temperature, although reactivity increases upon heating) and has the unsymmetrical structure N–N–O (N≡N O ↔ N=N =O): above 600 °C it dissociates by breaking the weaker N–O bond. Nitric oxide (NO)

5100-476: The eutrophication of water systems. Apart from its use in fertilisers and energy stores, nitrogen is a constituent of organic compounds as diverse as aramids used in high-strength fabric and cyanoacrylate used in superglue . 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 . The human body contains about 3% nitrogen by mass,

5202-579: The 19th century. Many physicists contributed to the development of quantum mechanics in the early-to-mid 20th century. New knowledge in the early 21st century includes a large increase in understanding physical cosmology . The broad and general study of nature, natural philosophy , was divided into several fields in the 19th century, when the concept of "science" received its modern shape. Specific categories emerged, such as "biology" and "biologist", "physics" and "physicist", "chemistry" and "chemist", among other technical fields and titles. The term physicist

SECTION 50

#1732802361928

5304-566: 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

5406-692: The Abington School district over their policy of mandatory Bible readings. To maintain standing in the case, Schempp (and later his younger siblings Roger and Donna) continued to fight this policy in the courts over several years. The Schempps were Unitarian Universalists , a theologically liberal religious community. The case was eventually decided in Schempps's favor by the Supreme Court in 1963, five years after he had graduated from high school. The precedent that this decision established, that

5508-643: The Battle over School Prayer . On November 26, 1956, Schempp staged a protest against the school requiring that each student read 10 Bible passages and the Lord's Prayer each day during homeroom . That day he brought a copy of the Qur'an and read from it; for this he was sent to the principal's office. With the help of his father, Edward Schempp, and the American Civil Liberties Union , they sued

5610-633: The French nitrogène , coined in 1790 by French chemist Jean-Antoine Chaptal (1756–1832), from the French nitre ( potassium nitrate , also called saltpetre ) and the French suffix -gène , "producing", from the Greek -γενής (-genes, "begotten"). Chaptal's meaning was that nitrogen is the essential part of nitric acid , which in turn was produced from nitre . In earlier times, nitre had been confused with Egyptian "natron" ( sodium carbonate ) – called νίτρον (nitron) in Greek ;– which, despite

5712-483: The German Stickstoff similarly refers to the same characteristic, viz. ersticken "to choke or suffocate") and still remains in English in the common names of many nitrogen compounds, such as hydrazine and compounds of the azide ion. Finally, it led to the name " pnictogens " for the group headed by nitrogen, from the Greek πνίγειν "to choke". The English word nitrogen (1794) entered the language from

5814-744: The 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

5916-860: The N anion, although charge separation is not actually complete even for these highly electropositive elements. However, the alkali metal azides NaN 3 and KN 3 , featuring the linear N 3 anion, are well-known, as are Sr(N 3 ) 2 and Ba(N 3 ) 2 . Azides of the B-subgroup metals (those in groups 11 through 16 ) are much less ionic, have more complicated structures, and detonate readily when shocked. Many covalent binary nitrides are known. Examples include cyanogen ((CN) 2 ), triphosphorus pentanitride (P 3 N 5 ), disulfur dinitride (S 2 N 2 ), and tetrasulfur tetranitride (S 4 N 4 ). The essentially covalent silicon nitride (Si 3 N 4 ) and germanium nitride (Ge 3 N 4 ) are also known: silicon nitride, in particular, would make

6018-450: The N≡N bond may be formed directly within a metal complex, for example by directly reacting coordinated ammonia (NH 3 ) with nitrous acid (HNO 2 ), but this is not generally applicable. Most dinitrogen complexes have colours within the range white-yellow-orange-red-brown; a few exceptions are known, such as the blue [{Ti( η -C 5 H 5 ) 2 } 2 -(N 2 )]. Nitrogen bonds to almost all

6120-889: The Separation of Church and State . In 1996, he received the Religious Liberty Award from Americans United. He is on the Advisory Board of the Secular Student Alliance and the Secular Coalition for America . He has traveled throughout the country talking about his experiences. In 2002, Schempp was elected to Abington Senior High School's hall of fame for his accomplishments in physics. In his acceptance speech, he said that "When I left Abington in 1958, it wasn’t clear that Abington ever wanted to see me again". The award did include

6222-418: The ability to form coordination complexes by donating its lone pairs of electrons. There are some parallels between the chemistry of ammonia NH 3 and water H 2 O. For example, the capacity of both compounds to be protonated to give NH 4 and H 3 O or deprotonated to give NH 2 and OH , with all of these able to be isolated in solid compounds. Nitrogen shares with both its horizontal neighbours

SECTION 60

#1732802361928

6324-399: The approach to problem-solving) developed in your education or experience as a physicist, in all cases regardless of whether the experience is in academia, industry, government, or elsewhere. Management of physics-related work qualifies, and so does appropriate graduate student work. The South African Institute of Physics also delivers a certification of Professional Physicist (Pr.Phys). At

6426-417: The atmosphere. The N: N ratio is commonly used in stable isotope analysis in the fields of geochemistry , hydrology , paleoclimatology and paleoceanography , where it is called δ N . Of the thirteen other isotopes produced synthetically, ranging from N to N, N has a half-life of ten minutes and the remaining isotopes have half-lives less than eight seconds. Given the half-life difference, N

6528-435: 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). Liquid nitrogen , a colourless fluid resembling water in appearance, but with 80.8% of the density (the density of liquid nitrogen at its boiling point is 0.808 g/mL), is a common cryogen . Solid nitrogen has many crystalline modifications. It forms

6630-416: The conjugate acid of the azide anion, and is similarly analogous to the hydrohalic acids . All four simple nitrogen trihalides are known. A few mixed halides and hydrohalides are known, but are mostly unstable; examples include NClF 2 , NCl 2 F, NBrF 2 , NF 2 H, NFH 2 , NCl 2 H , and NClH 2 . Nitrogen trifluoride (NF 3 , first prepared in 1928) is a colourless and odourless gas that

6732-555: The continuity of bonding types instead of the discrete and separate types that it implies. They are normally prepared by directly reacting a metal with nitrogen or ammonia (sometimes after heating), or by thermal decomposition of metal amides: Many variants on these processes are possible. The most ionic of these nitrides are those of the alkali metals and alkaline earth metals , Li 3 N (Na, K, Rb, and Cs do not form stable nitrides for steric reasons) and M 3 N 2 (M = Be, Mg, Ca, Sr, Ba). These can formally be thought of as salts of

6834-520: The designation of Professional Engineer (P. Eng.). This designation was unveiled at the CAP congress in 1999 and already more than 200 people carry this distinction. To get the certification, at minimum proof of honours bachelor or higher degree in physics or a closely related discipline must be provided. Also, the physicist must have completed, or be about to complete, three years of recent physics-related work experience after graduation. And, unless exempted,

6936-417: The destruction of hydrazine by reaction with monochloramine (NH 2 Cl) to produce ammonium chloride and nitrogen. Hydrogen azide (HN 3 ) was first produced in 1890 by the oxidation of aqueous hydrazine by nitrous acid. It is very explosive and even dilute solutions can be dangerous. It has a disagreeable and irritating smell and is a potentially lethal (but not cumulative) poison. It may be considered

7038-459: The early 1600s. The work on mechanics , along with a mathematical treatment of physical systems, was further developed by Christiaan Huygens and culminated in Newton's laws of motion and Newton's law of universal gravitation by the end of the 17th century. The experimental discoveries of Faraday and the theory of Maxwell's equations of electromagnetism were developmental high points during

7140-734: The elements in the periodic table except the first two noble gases , helium and neon , 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, Mn 6 N 5 , Mn 3 N 2 , Mn 2 N, Mn 4 N, and Mn x N 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

7242-467: The equilibrium between them, although sometimes dinitrogen tetroxide can react by heterolytic fission to nitrosonium and nitrate in a medium with high dielectric constant. Nitrogen dioxide is an acrid, corrosive brown gas. Both compounds may be easily prepared by decomposing a dry metal nitrate. Both react with water to form nitric acid . Dinitrogen tetroxide is very useful for the preparation of anhydrous metal nitrates and nitrato complexes, and it became

7344-421: The first gases to be identified: N 2 O ( nitrous oxide ), NO ( nitric oxide ), N 2 O 3 ( dinitrogen trioxide ), NO 2 ( nitrogen dioxide ), N 2 O 4 ( dinitrogen tetroxide ), N 2 O 5 ( dinitrogen pentoxide ), N 4 O ( nitrosylazide ), and N(NO 2 ) 3 ( trinitramide ). All are thermally unstable towards decomposition to their elements. One other possible oxide that has not yet been synthesised

7446-496: 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 . It also results in very large electrostatic forces of attraction between

7548-422: The fourth most abundant element in the body after oxygen, carbon, and hydrogen. The nitrogen cycle describes the movement of the element from the air, into the biosphere and organic compounds, then back into the atmosphere. 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,

7650-437: 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 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

7752-756: The increasing expectations and requirements for which any profession must take responsibility". Chartered Physicist is considered to be equal in status to Chartered Engineer, which the IoP also awards as a member of the Engineering Council UK, and other chartered statuses in the UK. It is also considered a "regulated profession" under the European professional qualification directives. The Canadian Association of Physicists can appoint an official designation called Professional Physicist ( P. Phys. ), similar to

7854-505: The interstitial nitrides of formulae MN, M 2 N, and M 4 N (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. They are opaque, very hard, and chemically inert, melting only at very high temperatures (generally over 2500 °C). They have a metallic lustre and conduct electricity as do metals. They hydrolyse only very slowly to give ammonia or nitrogen. The nitride anion (N )

7956-1180: The largest employer being the last. Physicists in academia or government labs tend to have titles such as Assistants, Professors , Sr./Jr. Scientist, or postdocs . As per the American Institute of Physics , some 20% of new physics Ph.D.s holds jobs in engineering development programs, while 14% turn to computer software and about 11% are in business/education. A majority of physicists employed apply their skills and training to interdisciplinary sectors (e.g. finance ). Job titles for graduate physicists include Agricultural Scientist , Air Traffic Controller , Biophysicist , Computer Programmer , Electrical Engineer , Environmental Analyst , Geophysicist , Medical Physicist , Meteorologist , Oceanographer , Physics Teacher / Professor / Researcher , Research Scientist , Reactor Physicist , Engineering Physicist , Satellite Missions Analyst, Science Writer , Stratigrapher , Software Engineer , Systems Engineer , Microelectronics Engineer , Radar Developer, Technical Consultant, etc. The majority of Physics terminal bachelor's degree holders are employed in

8058-525: The name, contained no nitrate. The earliest military, industrial, and agricultural applications of nitrogen compounds used saltpetre ( sodium nitrate or potassium nitrate), most notably in gunpowder , and later as fertiliser . In 1910, Lord Rayleigh discovered that an electrical discharge in nitrogen gas produced "active nitrogen", a monatomic allotrope of nitrogen. The "whirling cloud of brilliant yellow light" produced by his apparatus reacted with mercury to produce explosive mercury nitride . For

8160-574: The nitryl halides (XNO 2 ). The first is 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 2 ) and nitryl chloride (ClNO 2 ) are likewise reactive gases and vigorous halogenating agents. Nitrogen forms nine molecular oxides, some of which were

8262-679: The notation “Initiated school prayer suit against Abington which was eventually decided by U.S. Supreme Court in 1963.” Schempp's doctoral thesis was entitled Nuclear Quadrupole Resonance in Nitrogen Heterocycles . This work was the precursor to the development of magnetic resonance imaging (MRI) on which he continued to work for a substantial portion of his career. Physicist Physicists can apply their knowledge towards solving practical problems or to developing new technologies (also known as applied physics or engineering physics ). The study and practice of physics

8364-436: 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

8466-410: The organic nitrates nitroglycerin and nitroprusside control blood pressure by metabolising 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

8568-412: The other four are H , Li, B, and Ta. The relative abundance of N and N is practically constant in the atmosphere but can vary elsewhere, due to natural isotopic fractionation from biological redox reactions and the evaporation of natural ammonia or nitric acid . Biologically mediated reactions (e.g., assimilation , nitrification , and denitrification ) strongly control nitrogen dynamics in

8670-421: The other nonmetals are very complex and tend to lead to a mixture of products. Ammonia reacts on heating with metals to give nitrides. Many other binary nitrogen hydrides are known, but the most important are hydrazine (N 2 H 4 ) and hydrogen azide (HN 3 ). Although it is not a nitrogen hydride, hydroxylamine (NH 2 OH) is similar in properties and structure to ammonia and hydrazine as well. Hydrazine

8772-478: The oxidation of ammonia to nitrite, which occurs in the nitrogen cycle . Hyponitrite can act as a bridging or chelating bidentate ligand. Nitrous acid (HNO 2 ) is not known as a pure compound, but is a common component in gaseous equilibria and is an important aqueous reagent: its aqueous solutions may be made from acidifying cool aqueous nitrite ( NO 2 , bent) solutions, although already at room temperature disproportionation to nitrate and nitric oxide

8874-704: 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 does not share the proclivity of carbon for catenation . Like carbon, nitrogen tends to form ionic or metallic compounds with metals. Nitrogen forms an extensive series of nitrides with carbon, including those with chain-, graphitic- , and fullerenic -like structures. It resembles oxygen with its high electronegativity and concomitant capability for hydrogen bonding and

8976-583: The primary coolant system to the secondary steam cycle and is the primary means of detection for such leaks. 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 2 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

9078-433: The private sector. Other fields are academia, government and military service, nonprofit entities, labs and teaching. Typical duties of physicists with master's and doctoral degrees working in their domain involve research, observation and analysis, data preparation, instrumentation, design and development of industrial or medical equipment, computing and software development, etc. The highest honor awarded to physicists

9180-522: The production of fertilisers. Dinitrogen is able to coordinate to metals in five different ways. The more well-characterised ways are the end-on M←N≡N ( η ) and M←N≡N→M ( μ , bis- η ), in which the lone pairs on the nitrogen atoms are donated to the metal cation. The less well-characterised ways involve dinitrogen donating electron pairs from the triple bond, either as a bridging ligand to two metal cations ( μ , bis- η ) or to just one ( η ). The fifth and unique method involves triple-coordination as

9282-532: The public school does not have the right to sponsor religious exercises and then pressure students to take part in them has appeared time and time again in every church-state case focusing on religion in public schools. Schempp considers himself to be an atheist, but supports the Unitarian Universalist organizations and is a strong supporter of the ACLU and of the separation of church and state. He

9384-583: The same time, use of the Ostwald process (1902) to produce nitrates from industrial nitrogen fixation allowed the large-scale industrial production of nitrates as feedstock in the manufacture of explosives in the World Wars of the 20th century. A nitrogen atom has seven electrons. In the ground state, they are arranged in the electron configuration 1s 2s 2p x 2p y 2p z . It, therefore, has five valence electrons in

9486-557: The same time. 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 Ancient Greek : ἀζωτικός "no life", as it is an asphyxiant gas ; this name is used in a number of languages, and appears in the English names of some nitrogen compounds such as hydrazine , azides and azo compounds . Elemental nitrogen

9588-497: 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 2 into useful compounds , but at the same time it means that burning, exploding, or decomposing nitrogen compounds to form nitrogen gas releases large amounts of often useful energy. Synthetically produced ammonia and nitrates are key industrial fertilisers , and fertiliser nitrates are key pollutants in

9690-451: 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, and 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

9792-520: The storable oxidiser of choice for many rockets in both the United States and USSR by the late 1950s. This is because it is a hypergolic propellant in combination with a hydrazine -based rocket fuel and can be easily stored since it is liquid at room temperature. The thermally unstable and very reactive dinitrogen pentoxide (N 2 O 5 ) is the anhydride of nitric acid , and can be made from it by dehydration with phosphorus pentoxide . It

9894-489: 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. N, though also theoretically usable, has an integer nuclear spin of one and thus has a quadrupole moment that leads to wider and less useful spectra. N NMR nevertheless has complications not encountered in the more common H and C NMR spectroscopy. The low natural abundance of N (0.36%) significantly reduces sensitivity,

9996-420: The touch of a feather, shifting air currents, or even alpha particles . For this reason, small amounts of nitrogen triiodide are sometimes synthesised as a demonstration to high school chemistry students or as an act of "chemical magic". Chlorine azide (ClN 3 ) and bromine azide (BrN 3 ) are extremely sensitive and explosive. Two series of nitrogen oxohalides are known: the nitrosyl halides (XNO) and

10098-412: Was a component of air that does not support combustion was clear to Rutherford, although he was not aware that it was an element. Nitrogen was also studied at about the same time by Carl Wilhelm Scheele , Henry Cavendish , and Joseph Priestley , who referred to it as burnt air or phlogisticated air . French chemist Antoine Lavoisier referred to nitrogen gas as " mephitic air " or azote , from

10200-746: Was coined by William Whewell (also the originator of the term "scientist") in his 1840 book The Philosophy of the Inductive Sciences . A standard undergraduate physics curriculum consists of classical mechanics , electricity and magnetism , non-relativistic quantum mechanics , optics , statistical mechanics and thermodynamics , and laboratory experience. Physics students also need training in mathematics ( calculus , differential equations , linear algebra , complex analysis , etc.), and in computer science . Any physics-oriented career position requires at least an undergraduate degree in physics or applied physics, while career options widen with

10302-442: Was first found as a product of the thermal decomposition of FN 3 . Nitrogen trichloride (NCl 3 ) is a dense, volatile, and explosive liquid whose physical properties are similar to those of carbon tetrachloride , although one difference is that NCl 3 is easily hydrolysed by water while CCl 4 is not. It was first synthesised in 1811 by Pierre Louis Dulong , who lost three fingers and an eye to its explosive tendencies. As

10404-628: Was part of the Pittsburgh Explorer’s Group Nanga Parbat Expedition which was to be the first American group to reach the peak of Nanga Parbat in Pakistan . Schempp, who is retired, currently resides in Boston, Massachusetts . Stephen D. Solomon, a professor at New York University , has written a book about Schempp and the Supreme Court case entitled Ellery’s Protest: How One Young Man Defied Tradition and Sparked

#927072