Obręb  is a village in the administrative district of Gmina Mochowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Mochowo,  south-west of Sierpc, and  north-west of Warsaw.

References

Villages in Sierpc County


Osiek  is a village in the administrative district of Gmina Mochowo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Osiek


In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired valence electron.
With some exceptions, these unpaired electrons make radicals highly chemically reactive.  Many radicals spontaneously dimerize.  Most organic radicals have short lifetimes.

A notable example of a radical is the hydroxyl radical (HO·), a molecule that has one unpaired electron on the oxygen atom. Two other examples are triplet oxygen and triplet carbene (꞉) which have two unpaired electrons.

Radicals may be generated in a number of ways, but typical methods involve redox reactions, Ionizing radiation, heat, electrical discharges, and electrolysis are known to produce radicals. Radicals are intermediates in many chemical reactions, more so than is apparent from the balanced equations.

Radicals are important in combustion, atmospheric chemistry, polymerization, plasma chemistry, biochemistry, and many other chemical processes. A majority of natural products are generated by radical-generating enzymes.  In living organisms, the radicals superoxide and nitric oxide and their reaction products regulate many processes, such as control of vascular tone and thus blood pressure. They also play a key role in the intermediary metabolism of various biological compounds. Such radicals can even be messengers in a process dubbed redox signaling.  A radical may be trapped within a solvent cage or be otherwise bound.

Formation
Radicals are either (1) formed from spin-paired molecules or (2) from other radicals. Radicals are formed from spin-paired molecules through homolysis of weak bonds or electron transfer, also known as reduction. Radicals are formed from other radicals through substitution, addition, and elimination reactions.

Radical formation from spin-paired molecules

Homolysis

Homolysis makes two new radicals from a spin-paired molecule by breaking a covalent bond, leaving each of the fragments with one of the electrons in the bond. Because breaking a chemical bond requires energy, homolysis occurs under the addition of heat or light. The bond dissociation energy associated with homolysis depends on the stability of a given compound, and some weak bonds are able to homolyze at relatively lower temperatures.

Some homolysis reactions are particularly important because they serve as an initiator for other radical reactions. One such example is the homolysis of halogens, which occurs under light and serves as the driving force for radical halogenation reactions.

Another notable reaction is the homolysis of dibenzoyl peroxide, which results in the formation of two benzoyloxy radicals and acts as an initiator for many radical reactions.

Reduction
Radicals can also form when a single electron is added to a spin-paired molecule, resulting in an electron transfer. This reaction, also called reduction, usually takes place with an alkali metal donating an electron to another spin-paired molecule.

Radical formation from other radicals

Abstraction

Hydrogen abstraction describes when a hydrogen atom is removed from a hydrogen donor molecule (e.g. tin or silicon hydride) with its one electron. Abstraction produces a new radical and a new spin-paired molecule. This is different from homolysis, which results in two radicals from a single spin-paired molecule and doesn't include a radical as its reactant. Hydrogen abstraction is a fundamental process in radical chemistry because it serves as the final propagation step in many chemical reactions, converting carbon radicals into stable molecules. The figure to the right shows a radical abstraction between a benzoyloxy radical and a hydrogen bromide molecule, resulting in the production of a benzoic acid molecule and a bromine radical.

Addition

Radical addition describes when a radical is added to a spin-paired molecule to form a new radical. The figure on the right shows the addition of a bromine radical to an alkene. Radical addition follows the Anti -Markovnikov rule, where the substituent is added to the less substituted carbon atom.

Elimination
Radical elimination can be viewed as the reverse of radical addition. In radical elimination, an unstable radical compound breaks down into a spin-paired molecule and a new radical compound. Shown below is an example of a radical elimination reaction, where a benzoyloxy radical breaks down into a phenyl radical and a carbon dioxide molecule.

Stability

Stability of organic radicals

Although organic radicals are generally stable intrinsically (in isolation), practically speaking their existence is only transient because they tend to dimerize. Some are quite long-lived. Generally organic radicals are stabilized by any or all of these factors: presence of electronegativity, delocalization, and steric hindrance.  The compound 2,2,6,6-tetramethylpiperidinyloxyl illustrates the combination of all three factors.  It is a commercially available solid that, aside from being magnetic, behaves like a normal organic compound.

Electronegativity
Organic radicals are inherently electron deficient thus the greater the electronegativity of the atom on which the unpaired electron resides the less stable the radical. Between carbon, nitrogen, and oxygen, for example, carbon is the most stable and oxygen the least stable.

Electronegativity also factors into the stability of carbon atoms of different hybridizations. Greater s-character correlates to higher electronegativity of the carbon atom (due to the close proximity of s orbitals to the nucleus), and the greater the electronegativity the less stable a radical. sp-hybridized carbons (50% s-character) form the least stable radicals compared to sp3-hybridized carbons (25% s-character) which form the most stable radicals.

Delocalization
The delocalization of electrons across the structure of a radical, also known as its ability to form one or more resonance structures, allows for the electron-deficiency to be spread over several atoms, minimizing instability. Delocalization usually occurs in the presence of electron-donating groups, such as hydroxyl groups (−OH), ethers (−OR), adjacent alkenes, and amines (−NH2 or −NR), or electron-withdrawing groups, such as C=O or C≡N.

Delocalization effects can also be understood using molecular orbital theory as a lens, more specifically, by examining the intramolecular interaction of the unpaired electron with a donating group's pair of electrons or the empty π* orbital of an electron-withdrawing group in the form of a molecular orbital diagram. The HOMO of a radical is singly-occupied hence the orbital is aptly referred to as the SOMO, or the Singly-Occupied Molecular Orbital. For an electron-donating group, the SOMO interacts with the lower energy lone pair to form a new lower-energy filled bonding-orbital and a singly-filled new SOMO, higher in energy than the original. While the energy of the unpaired electron has increased, the decrease in energy of the lone pair forming the new bonding orbital outweighs the increase in energy of the new SOMO, resulting in a net decrease of the energy of the molecule. Therefore, electron-donating groups help stabilize radicals.

With a group that is instead electron-withdrawing, the SOMO then interacts with the empty π* orbital. There are no electrons occupying the higher energy orbital formed, while a new SOMO forms that is lower in energy. This results in a lower energy and higher stability of the radical species. Both donating groups and withdrawing groups stabilize radicals.

Another well-known albeit weaker form of delocalization is hyperconjugation. In radical chemistry, radicals are stabilized by hyperconjugation with adjacent alkyl groups. The donation of sigma (σ) C−H bonds into the partially empty radical orbitals helps to differentiate the stabilities of radicals on tertiary, secondary, and primary carbons. Tertiary carbon radicals have three σ C-H bonds that donate, secondary radicals only two, and primary radicals only one. Therefore, tertiary radicals are the most stable and primary radicals the least stable.

Steric hindrance

Most simply, the greater the steric hindrance the more difficult it is for reactions to take place, and the radical form is favored by default. For example, compare the hydrogen-abstracted form of N-hydroxypiperidine to the molecule TEMPO. TEMPO, or (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl, is too sterically hindered by the additional methyl groups to react making it stable enough to be sold commercially in its radical form. N-Hydroxypiperidine, however, does not have the four methyl groups to impede the way of a reacting molecule so the structure is unstable.

Facile H-atom donors
The stability of many (or most) organic radicals is not indicated by their isolability but is manifested in their ability to function as donors of H•.  This property reflects a weakened bond to hydrogen, usually O−H but sometimes N−H or C−H.  This behavior is important because these H• donors serve as antioxidants in biology and in commerce.  Illustrative is α-tocopherol (vitamin E). The tocopherol radical itself is insufficiently stable for isolation, but the parent molecule is a highly effective hydrogen-atom donor. The C−H bond is weakened in triphenylmethyl (trityl) derivatives.

Inorganic radicals
A large variety of inorganic radicals are stable and in fact isolable.  Examples include most first-row transition metal complexes.

With regard to main group radicals, the most abundant radical in the universe is also the most abundant chemical in the universe, H•.  Most main group radicals are not however isolable, despite their intrinsic stability.  Hydrogen radicals for example combine eagerly to form H2.  Nitric oxide (NO) is well known example of an isolable inorganic radical.  Fremy's salt (Potassium nitrosodisulfonate, (KSO3)2NO) is a related example. Many thiazyl radicals are known, despite limited extent of π resonance stabilization.

Many radicals can be envisioned as the products of breaking of covalent bonds by homolysis. The homolytic bond dissociation energies, usually abbreviated as "ΔH°" are a measure of bond strength. Splitting H2 into 2 H•, for example, requires a ΔH° of +435 kJ/mol, while splitting Cl2 into two Cl• requires a ΔH° of +243 kJ/mol.  For weak bonds, homolysis can be induced thermally.  Strong bonds require high energy photons or even flames to induce homolysis.

Diradicals
Diradicals are molecules containing two radical centers. Dioxygen (O2) is an important example of a stable diradical. Singlet oxygen, the lowest-energy non-radical state of dioxygen, is less stable than the diradical due to Hund's rule of maximum multiplicity. The relative stability of the oxygen diradical is primarily due to the spin-forbidden nature of the triplet-singlet transition required for it to grab electrons, i.e., "oxidize". The diradical state of oxygen also results in its paramagnetic character, which is demonstrated by its attraction to an external magnet. Diradicals can also occur in metal-oxo complexes, lending themselves for studies of spin forbidden reactions in transition metal chemistry. Carbenes in their triplet state can be viewed as diradicals centred on the same atom, while these are usually highly reactive persistent carbenes are known, with N-heterocyclic carbenes being the most common example.

Triplet carbenes and nitrenes are diradicals.  Their chemical properties are distinct from the properties of their singlet analogues.

Occurrence of radicals

Combustion

A familiar radical reaction is combustion. The oxygen molecule is a stable diradical, best represented by •O–O•. Because spins of the electrons are parallel, this molecule is stable.  While the ground state of oxygen is this unreactive spin-unpaired (triplet) diradical, an extremely reactive spin-paired (singlet) state is available. For combustion to occur, the energy barrier between these must be overcome. This barrier can be overcome by heat, requiring high temperatures.  The triplet-singlet transition is also "forbidden".  This presents an additional barrier to the reaction.  It also means molecular oxygen is relatively unreactive at room temperature except in the presence of a catalytic heavy atom such as iron or copper.

Combustion consists of various radical chain reactions that the singlet radical can initiate. The flammability of a given material strongly depends on the concentration of radicals that must be obtained before initiation and propagation reactions dominate leading to combustion of the material. Once the combustible material has been consumed, termination reactions again dominate and the flame dies out.  As indicated,  promotion of propagation or termination reactions alters flammability.  For example, because lead itself deactivates radicals in the gasoline-air mixture, tetraethyl lead was once commonly added to gasoline. This prevents the combustion from initiating in an uncontrolled manner or in unburnt residues (engine knocking) or premature ignition (preignition).

When a hydrocarbon is burned, a large number of different oxygen radicals are involved. Initially, hydroperoxyl radical (HOO•) are formed. These then react further to give organic hydroperoxides that break up into hydroxyl radicals (HO•).

Polymerization
Many polymerization reactions are initiated by radicals. Polymerization involves an initial radical adding to non-radical (usually an alkene) to give new radicals.  This process is the basis of the radical chain reaction. The art of polymerization entails the method by which the initiating radical is introduced.  For example, methyl methacrylate (MMA) can be polymerized to produce Poly(methyl methacrylate) (PMMA - Plexiglas or Perspex) via a repeating series of radical addition steps:

Newer radical polymerization methods are known as living radical polymerization.  Variants include reversible addition-fragmentation chain transfer (RAFT) and atom transfer radical polymerization (ATRP).

Being a prevalent radical, O2 reacts with many organic compounds to generate radicals together with the hydroperoxide radical. Drying oils and alkyd paints harden due to radical crosslinking initiated by oxygen from the atmosphere.

Atmospheric radicals

The most common radical in the lower atmosphere is molecular dioxygen. Photodissociation of source molecules produces other radicals. In the lower atmosphere, important radical are produced by the photodissociation of nitrogen dioxide to an oxygen atom and nitric oxide (see  below), which plays a key role in smog formation—and the photodissociation of ozone to give the excited oxygen atom O(1D) (see  below). The net and return reactions are also shown ( and , respectively).

In the upper atmosphere, the photodissociation of normally unreactive chlorofluorocarbons (CFCs) by solar ultraviolet radiation is an important source of radicals (see eq. 1 below). These reactions give the chlorine radical, Cl•, which catalyzes the conversion of ozone to O2, thus facilitating ozone depletion (– below).

Such reactions cause the depletion of the ozone layer, especially since the chlorine radical is free to engage in another reaction chain; consequently, the use of chlorofluorocarbons as refrigerants has been restricted.

In biology

Radicals play important roles in biology.  Many of these are necessary for life, such as the intracellular killing of bacteria by phagocytic cells such as granulocytes and macrophages. Radicals are involved in cell signalling processes, known as redox signaling.  For example, radical attack of linoleic acid produces a series of 13-hydroxyoctadecadienoic acids and 9-hydroxyoctadecadienoic acids, which may act to regulate localized tissue inflammatory and/or healing responses, pain perception, and the proliferation of malignant cells. Radical attacks on arachidonic acid and docosahexaenoic acid produce a similar but broader array of signaling products.

Radicals may also be involved in Parkinson's disease, senile and drug-induced deafness, schizophrenia, and Alzheimer's. The classic free-radical syndrome, the iron-storage disease hemochromatosis, is typically associated with a constellation of free-radical-related symptoms including movement disorder, psychosis, skin pigmentary melanin abnormalities, deafness, arthritis, and diabetes mellitus. The free-radical theory of aging proposes that radicals underlie the aging process itself. Similarly, the process of mitohormesis suggests that repeated exposure to radicals may extend life span.

Because radicals are necessary for life, the body has a number of mechanisms to minimize radical-induced damage and to repair damage that occurs, such as the enzymes superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase. In addition, antioxidants play a key role in these defense mechanisms. These are often the three vitamins, vitamin A, vitamin C and vitamin E and polyphenol antioxidants. Furthermore, there is good evidence indicating that bilirubin and uric acid can act as antioxidants to help neutralize certain radicals. Bilirubin comes from the breakdown of red blood cells' contents, while uric acid is a breakdown product of purines. Too much bilirubin, though, can lead to jaundice, which could eventually damage the central nervous system, while too much uric acid causes gout.

Reactive oxygen species
Reactive oxygen species or ROS are species such as superoxide, hydrogen peroxide, and hydroxyl radical, commonly associated with cell damage. ROS form as a natural by-product of the normal metabolism of oxygen and have important roles in cell signaling.
Two important oxygen-centered radicals are superoxide and hydroxyl radical. They derive from molecular oxygen under reducing conditions. However, because of their reactivity, these same radicals can participate in unwanted side reactions resulting in cell damage. Excessive amounts of these radicals can lead to cell injury and death, which may contribute to many diseases such as cancer, stroke, myocardial infarction, diabetes and major disorders. Many forms of cancer are thought to be the result of reactions between radicals and DNA, potentially resulting in mutations that can adversely affect the cell cycle and potentially lead to malignancy. Some of the symptoms of aging such as atherosclerosis are also attributed to radical induced oxidation of cholesterol to 7-ketocholesterol. In addition radicals contribute to alcohol-induced liver damage, perhaps more than alcohol itself. Radicals produced by cigarette smoke are implicated in inactivation of alpha 1-antitrypsin in the lung. This process promotes the development of emphysema.

Oxybenzone has been found to form radicals in sunlight, and therefore may be associated with cell damage as well. This only occurred when it was combined with other ingredients commonly found in sunscreens, like titanium oxide and octyl methoxycinnamate.

ROS attack the polyunsaturated fatty acid, linoleic acid, to form a series of 13-hydroxyoctadecadienoic acid and 9-hydroxyoctadecadienoic acid products that serve as signaling molecules that may trigger responses that counter the tissue injury which caused their formation.  ROS attacks other polyunsaturated fatty acids, e.g. arachidonic acid and docosahexaenoic acid, to produce a similar series of signaling products.

Reactive oxygen species are also used in controlled reactions involving singlet dioxygen  known as type II photooxygenation reactions after Dexter energy transfer (triplet-triplet annihilation) from natural triplet dioxygen  and triplet excited state of a photosensitizer. Typical chemical transformations with this singlet dioxygen species involve, among others, conversion of cellulosic biowaste into new poylmethine dyes.

History and nomenclature

Until late in the 20th century the word "radical" was used in chemistry to indicate any connected group of atoms, such as a methyl group or a carboxyl, whether it was part of a larger molecule or a molecule on its own. A radical is often known as an R group. The qualifier "free" was then needed to specify the unbound case.  Following recent nomenclature revisions, a part of a larger molecule is now called a functional group or substituent, and "radical" now implies "free".  However, the old nomenclature may still appear in some books.

The term radical was already in use when the now obsolete radical theory was developed. Louis-Bernard Guyton de Morveau introduced the phrase "radical" in 1785 and the phrase was employed by Antoine Lavoisier in 1789 in his Traité Élémentaire de Chimie. A radical was then identified as the root base of certain acids (the Latin word "radix" meaning "root"). Historically, the term radical in radical theory was also used for bound parts of the molecule, especially when they remain unchanged in reactions. These are now called functional groups. For example, methyl alcohol was described as consisting of a methyl "radical" and a hydroxyl "radical". Neither are radicals in the modern chemical sense, as they are permanently bound to each other, and have no unpaired, reactive electrons; however, they can be observed as radicals in mass spectrometry when broken apart by irradiation with energetic electrons.

In a modern context the first organic (carbon–containing) radical identified was the triphenylmethyl radical, (C6H5)3C•.  This species was discovered by Moses Gomberg in 1900. In 1933 Morris S. Kharasch and Frank Mayo proposed that free radicals were responsible for anti-Markovnikov addition of hydrogen bromide to allyl bromide.

In most fields of chemistry, the historical definition of radicals contends that the molecules have nonzero electron spin. However, in fields including spectroscopy and astrochemistry, the definition is slightly different. Gerhard Herzberg, who won the Nobel prize for his research into the electron structure and geometry of radicals, suggested a looser definition of free radicals: "any transient (chemically unstable) species (atom, molecule, or ion)". The main point of his suggestion is that there are many chemically unstable molecules that have zero spin, such as C2, C3, CH2 and so on. This definition is more convenient for discussions of transient chemical processes and astrochemistry; therefore researchers in these fields prefer to use this loose definition.

Depiction in chemical reactions

In chemical equations, radicals are frequently denoted by a dot placed immediately to the right of the atomic symbol or molecular formula as follows:

Radical reaction mechanisms use single-headed arrows to depict the movement of single electrons:

The homolytic cleavage of the breaking bond is drawn with a "fish-hook" arrow to distinguish from the usual movement of two electrons depicted by a standard curly arrow. The second electron of the breaking bond also moves to pair up with the attacking radical electron.

Radicals also take part in radical addition and radical substitution as reactive intermediates. Chain reactions involving radicals can usually be divided into three distinct processes.  These are initiation, propagation, and termination.
Initiation reactions are those that result in a net increase in the number of radicals. They may involve the formation of radicals from stable species as in Reaction 1 above or they may involve reactions of radicals with stable species to form more radicals.
Propagation reactions are those reactions involving radicals in which the total number of radicals remains the same.
Termination reactions are those reactions resulting in a net decrease in the number of radicals. Typically two radicals combine to form a more stable species, for example:
2 Cl• → Cl2

See also
 Electron pair
 Globally Harmonized System of Classification and Labelling of Chemicals
 Hofmann–Löffler reaction
Free radical research
 ARC Centre of Excellence for Free Radical Chemistry and Biotechnology

References

Articles containing video clips
Biological processes
Biomolecules
Chemical bonding
Environmental chemistry
Senescence


Rokicie  is a village in the administrative district of Gmina Mochowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north-west of Mochowo,  west of Sierpc, and  north-west of Warsaw.

References

Rokicie


In chemistry and atomic physics, an electron shell may be thought of as an orbit that electrons follow around an atom's nucleus. The closest shell to the nucleus is called the "1 shell" (also called the "K shell"), followed by the "2 shell" (or "L shell"), then the "3 shell" (or "M shell"), and so on farther and farther from the nucleus. The shells correspond to the principal quantum numbers (n = 1, 2, 3, 4 ...) or are labeled alphabetically with the letters used in X-ray notation (K, L, M, ...). A useful guide when understanding electron shells in atoms is to note that each row on the conventional periodic table of elements represents an electron shell.

Each shell can contain only a fixed number of electrons: the first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on. The general formula is that the nth shell can in principle hold up to 2(n2) electrons. For an explanation of why electrons exist in these shells, see electron configuration.

Each shell consists of one or more subshells, and each subshell consists of one or more atomic orbitals.

History
In 1913 Bohr proposed a model of the atom, giving the arrangement of electrons in their sequential orbits. At that time, Bohr allowed the capacity of the inner orbit of the atom to increase to eight electrons as the atoms got larger, and "in the scheme given below the number of electrons in this [outer] ring is arbitrary put equal to the normal valency of the corresponding element." Using these and other constraints, he proposed configurations that are in accord with those now known only for the first six elements. "From the above we are led to the following possible scheme for the arrangement of the electrons in light atoms:"

The shell terminology comes from Arnold Sommerfeld's modification of the 1913 Bohr model. During this period Bohr was working with Walther Kossel, whose papers in 1914 and in 1916 called the orbits "shells". Sommerfeld retained Bohr's planetary model, but added mildly elliptical orbits (characterized by additional quantum numbers  and m) to explain the fine spectroscopic structure of some elements. The multiple electrons with the same principal quantum number (n) had close orbits that formed a "shell" of positive thickness instead of the circular orbit of Bohr's model which orbits called "rings" were described by a plane.

The existence of electron shells was first observed experimentally in Charles Barkla's and Henry Moseley's X-ray absorption studies. Moseley's work did not directly concern the study of electron shells, because he was trying to prove that the periodic table was not arranged by weight, but by the charge of the protons in the nucleus. However, because the number of electrons in an electrically neutral atom equals the number of protons, this work was extremely important to Niels Bohr who mentioned Moseley's work several times in his 1962 interview. Moseley was part of Rutherford's group, as was Niels Bohr. Moseley measured the frequencies of X-rays emitted by every element between calcium and zinc and found that the frequencies became greater as the elements got heavier. This led to the theory that electrons were emitting X-rays when they were shifted to lower shells. This led to the conclusion that the electrons were in Kossel's shells with a definite limit per shell, labeling the shells with the letters K, L, M, N, O, P, and Q. The origin of this terminology was alphabetic. Barkla, who worked independently from Moseley as an X-ray spectrometry experimentalist, first noticed two distinct types of scattering from shooting X-rays at elements in 1909 and named them "A" and "B". Barkla described these two types of X-ray diffraction: the first was unconnected with the type of material used in the experiment and could be polarized. The second diffraction beam he called "fluorescent" because it depended on the irradiated material. It was not known what these lines meant at the time, but in 1911 Barkla decided there might be scattering lines previous to "A", so he began at "K". However, later experiments indicated that the K absorption lines are produced by the innermost electrons. These letters were later found to correspond to the n values 1, 2, 3, etc. that were used in the Bohr model. They are used in the spectroscopic Siegbahn notation.

The work of assigning electrons to shells was continued from 1913 to 1925 by many chemists and a few physicists. Niels Bohr was one of the few physicists who followed the chemist's work of defining the periodic table, while Arnold Sommerfeld worked more on trying to make a relativistic working model of the atom that would explain the fine structure of the spectra from a classical orbital physics standpoint through the Atombau approach. Einstein and Rutherford, who did not follow chemistry, were unaware of the chemists who were developing electron shell theories of the periodic table from a chemistry point of view, such as Irving Langmuir, Charles Bury, J.J. Thomson, and Gilbert Lewis, who all introduced corrections to Bohr's model such as a maximum of two electrons in the first shell, eight in the next and so on, and were responsible for explaining valency in the outer electron shells, and the building up of atoms by adding electrons to the outer shells. So when Bohr outlined his electron shell atomic theory in 1922, there was no mathematical formula for the theory. So Rutherford said he was hard put "to form an idea of how you arrive at your conclusions". Einstein said of Bohr's 1922 paper that his "electron-shells of the atoms together with their significance for chemistry appeared to me like a miracle – and appears to me as a miracle even today". Arnold Sommerfeld, who had followed the Atombau structure of electrons instead of Bohr who was familiar with the chemists' views of electron structure, spoke of Bohr's 1921 lecture and 1922 article on the shell model as "the greatest advance in atomic structure since 1913". However, the electron shell development of Niels Bohr was basically the same theory as that of the chemist Charles Rugeley Bury in his 1921 paper.

As work continued on the electron shell structure of the Sommerfeld-Bohr Model, Sommerfeld had introduced three "quantum numbers n, k, and m, that described the size of the orbit, the shape of the orbit, and the direction in which the orbit was pointing." Because we use k for the Boltzmann constant, the azimuthal quantum number was changed to ℓ. When the modern quantum mechanics theory was put forward based on Heisenberg's matrix mechanics and Schrödinger's wave equation, these quantum numbers were kept in the current quantum theory but were changed to n being the principal quantum number, and m being the magnetic quantum number.

However, the final form of the electron shell model still in use today for the number of electrons in shells was discovered in 1923 by Edmund Stoner, who introduced the principle that the nth shell was described by 2(n2). Seeing this in 1925, Wolfgang Pauli added a fourth quantum number, "spin", during the old quantum theory period of the Sommerfeld-Bohr Solar System atom to complete the modern electron shell theory.

Subshells

Each shell is composed of one or more subshells, which are themselves composed of atomic orbitals. For example, the first (K) shell has one subshell, called 1s; the second (L) shell has two subshells, called 2s and 2p; the third shell has 3s, 3p, and 3d; the fourth shell has 4s, 4p, 4d and 4f; the fifth shell has 5s, 5p, 5d, and 5f and can theoretically hold more in the 5g subshell that is not occupied in the ground-state electron configuration of any known element. The various possible subshells are shown in the following table:

 The first column is the "subshell label", a lowercase-letter label for the type of subshell. For example, the "4s subshell" is a subshell of the fourth (N) shell, with the type (s) described in the first row.
 The second column is the azimuthal quantum number (ℓ) of the subshell. The precise definition involves quantum mechanics, but it is a number that characterizes the subshell.
 The third column is the maximum number of electrons that can be put into a subshell of that type. For example, the top row says that each s-type subshell (1s, 2s, etc.) can have at most two electrons in it. Each of the following subshells (p, d, f, g) can have 4 more electrons than the one preceding it.
 The fourth column says which shells have a subshell of that type. For example, looking at the top two rows, every shell has an s subshell, while only the second shell and higher have a p subshell (i.e., there is no "1p" subshell).
 The final column gives the historical origin of the labels s, p, d, and f. They come from early studies of atomic spectral lines. The other labels, namely g, h, and i, are an alphabetic continuation following the last historically originated label of f.

Number of electrons in each shell

Each subshell is constrained to hold  electrons at most, namely:
 Each s subshell holds at most 2 electrons
 Each p subshell holds at most 6 electrons
 Each d subshell holds at most 10 electrons
 Each f subshell holds at most 14 electrons
 Each g subshell holds at most 18 electrons

Therefore, the K shell, which contains only an s subshell, can hold up to 2 electrons; the L shell, which contains an s and a p, can hold up to 2 + 6 = 8 electrons, and so forth; in general, the nth shell can hold up to 2n2 electrons.

Although that formula gives the maximum in principle, in fact that maximum is only achieved (in known elements) for the first four shells (K, L, M, N). No known element has more than 32 electrons in any one shell. This is because the subshells are filled according to the Aufbau principle. The first elements to have more than 32 electrons in one shell would belong to the g-block of period 8 of the periodic table. These elements would have some electrons in their 5g subshell and thus have more than 32 electrons in the O shell (fifth principal shell).

Subshell energies and filling order

Although it is sometimes stated that all the electrons in a shell have the same energy, this is an approximation. However, the electrons in one subshell do have exactly the same level of energy, with later subshells having more energy per electron than earlier ones. This effect is great enough that the energy ranges associated with shells can overlap.

The filling of the shells and subshells with electrons proceeds from subshells of lower energy to subshells of higher energy. This follows the n + ℓ rule which is also commonly known as the Madelung rule. Subshells with a lower n + ℓ value are filled before those with higher n + ℓ values. In the case of equal n + ℓ values, the subshell with a lower n value is filled first.

Because of this, the later shells are filled over vast sections of the periodic table. The K shell fills in the first period (hydrogen and helium), while the L shell fills in the second (lithium to neon). However, the M shell starts filling at sodium (element 11) but does not finish filling till copper (element 29), and the N shell is even slower: it starts filling at potassium (element 19) but does not finish filling till ytterbium (element 70). The O, P, and Q shells begin filling in the known elements, but they are not complete even at the heaviest known element, oganesson (element 118).

List of elements with electrons per shell
The list below gives the elements arranged by increasing atomic number and shows the number of electrons per shell. At a glance, the subsets of the list show obvious patterns. In particular, every set of five elements () before each noble gas (group 18, ) heavier than helium have successive numbers of electrons in the outermost shell, namely three to seven.

Sorting the table by chemical group shows additional patterns, especially with respect to the last two outermost shells. (Elements 57 to 71 belong to the lanthanides, while 89 to 103 are the actinides.)

The list below is primarily consistent with the Aufbau principle. However, there are a number of exceptions to the rule; for example palladium (atomic number 46) has no electrons in the fifth shell, unlike other atoms with lower atomic number. The elements past 108 have such short half-lives that their electron configurations have not yet been measured, and so predictions have been inserted instead.

See also

 Periodic table (electron configurations)
 Electron counting
 18-electron rule
 Core charge

References

Electron
Atomic physics
Quantum mechanics
Chemical bonding


Romatowo  is a village in the administrative district of Gmina Mochowo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Romatowo


Śniechy  is a village in the administrative district of Gmina Mochowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Sulkowo Rzeczne  is a village in the administrative district of Gmina Mochowo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Sulkowo Rzeczne


Sulkowo-Bariany  is a village in the administrative district of Gmina Mochowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Sierpc and  north-west of Warsaw.

References

Sulkowo-Bariany


Żabiki  is a village in the administrative district of Gmina Mochowo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Załszyn  is a village in the administrative district of Gmina Mochowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Zglenice Duże  is a village in the administrative district of Gmina Mochowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Zglenice Małe  is a village in the administrative district of Gmina Mochowo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Zglenice-Budy  is a village in the administrative district of Gmina Mochowo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Zglenice-Budy


Żółtowo  is a village in the administrative district of Gmina Mochowo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Żuki  is a village in the administrative district of Gmina Mochowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Żurawin  is a village in east-central Poland, in the administrative district of Gmina Mochowo, within Sierpc County, Masovian Voivodeship. It lies approximately  north-west of Mochowo,  south-west of Sierpc, and  north-west of Warsaw.

References

Villages in Sierpc County


Żurawinek  is a village in the administrative district of Gmina Mochowo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Babiec Piaseczny  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  east of Sierpc and  north-west of Warsaw.

References

Babiec Piaseczny


Babiec Rżały  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Babiec-Więczanki  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in East-Central Poland.

References

Villages in Sierpc County


Borowo  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north-west of Rościszewo,  north-east of Sierpc, and  north-west of Warsaw.

References

Borowo


Bryski  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  west of Rościszewo,  north of Sierpc, and  north-west of Warsaw.

References

Bryski


Komorowo  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north-west of Rościszewo,  north-east of Sierpc, and  north-west of Warsaw.

References

Komorowo


Kownatka  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Kownatka


Kuski  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south of Rościszewo,  east of Sierpc, and  north-west of Warsaw.

References

Kuski


Fontana Rosa is a historic garden situated on the Avenue Blasco Ibáñez  in Menton, Alpes-Maritimes, on the French Riviera.

The Spanish writer Vicente Blasco Ibáñez (1869–1928) began to build it from 1922 on, and he set up home here with his second wife, Elena, and died there in 1928.

This garden with Spanish and Menton pottery is found in avenue Blasco Ibanez, near Garavan station, and was created a  Historical Monument in 1990.

It is also called "Le Jardin des Romanciers" (El Jardín de los Novelistas/The Garden of Novelists), and was frequented by celebrities such as Jean Cocteau. It was the place where Blasco Ibáñez wrote the novel Mare Nostrum (filmed in 1926 as Torrent).

The garden inspired by Andalusian and Arabian-Persian styles contains species such as Ficus macrophylla, Araucaria heterophylla , palm trees, banana trees or scented rosebushes. It is a tribute to Vicente's favourite writers : Cervantes, Dickens, Shakespeare or Honoré de Balzac, whose busts can be found at the entrance and to whom he dedicated several fountains and rotundas.

Its main buildings are a small elevated villa with polychromatic pottery which houses a library and a personal movie projector room, and a main house (Villa Emilia) in the lower part of the property that dates from the 19th century. The architectural complex also has an aquarium, a colonnade, a concrete pergola, pillars, flower vases, ceramic-panelled benches around the main house and a big round, steel pergola covering a long staircase in the middle of the property.

After Blasco Ibáñez's death here, his son inherited the property. In 1939, it was sacked during the war and later abandoned for more than thirty years. Blasco Ibáñez's son gave it to the commune of Menton in 1970. Since 1985, the buildings have been restored and, as from 1991, the pottery too. Still undergoing restoration, the garden may be visited only by guided tour, on Monday and Friday at 10am.

References

External links
Official pages at Menton.com

French Riviera
Gardens in Menton
Houses in Alpes-Maritimes
Modernist architecture in France
Monuments historiques of Alpes-Maritimes
Parks in France
Urban public parks
Villas in France


Lipniki  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north-east of Rościszewo,  east of Sierpc, and  north-west of Warsaw.

References

Lipniki


Łukomie  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north-east of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Łukomie-Kolonia  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Nowe Rościszewo  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Nowy Zamość () is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Ostrów  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  east of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Pianki  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north-east of Sierpc and  north-west of Warsaw.

References

Pianki


Polik  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north of Rościszewo,  north-east of Sierpc, and  north-west of Warsaw.

References

Polik


Puszcza  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Puszcza


Rościszewo  is a village in Sierpc County, Masovian Voivodeship, in east-central Poland. It is the seat of the gmina (administrative district) called Gmina Rościszewo. It lies approximately  east of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Rumunki-Chwały  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Rzeszotary-Chwały  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Rzeszotary-Gortaty  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-east of Rościszewo,  east of Sierpc, and  north-west of Warsaw.

References

Rzeszotary-Gortaty


Rzeszotary-Pszczele  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Rzeszotary-Pszczele


Rzeszotary-Stara Wieś  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Rzeszotary-Zawady  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Rzeszotary-Zawady


Śniedzanowo  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  east of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Stopin  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north-east of Sierpc and  north-west of Warsaw.

References

Stopin


Hydrochloric acid, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride with the chemical formula HCl(aq). It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the digestive systems of most animal species, including humans. Hydrochloric acid is an important laboratory reagent and industrial chemical.

Etymology
Because it was produced from rock salt according to the methods of Johann Rudolph Glauber, hydrochloric acid was historically called by European alchemists spirits of salt or acidum salis (salt acid). Both names are still used, especially in other languages, such as , , , , , , , , and  (yánsuān).

Gaseous HCl was called marine acid air.  The name muriatic acid has the same origin (muriatic means "pertaining to brine or salt", hence muriate means hydrochloride), and this name is still sometimes used. The name hydrochloric acid was coined by the French chemist Joseph Louis Gay-Lussac in 1814.

History

9th–10th century
In the early tenth century, the Persian physician and alchemist Abu Bakr al-Razi (–925, Latin: Rhazes) conducted experiments with sal ammoniac (ammonium chloride) and vitriol (hydrated sulfates of various metals), which he distilled together, thus producing the gas hydrogen chloride. In doing so, al-Razi may have stumbled upon a primitive method for producing hydrochloric acid, as perhaps manifested in the following recipe from his  ("The Book of Secrets"):

However, it appears that in most of his experiments al-Razi disregarded the gaseous products, concentrating instead on the color changes that could be effected in the residue. According to Robert P. Multhauf, hydrogen chloride was produced many times without clear recognition that, by dissolving it in water, hydrochloric acid may be produced.

11th–13th century
Drawing on al-Razi's experiments, the  ("On Alums and Salts"), an eleventh- or twelfth-century Arabic text falsely attributed to al-Razi and translated into Latin by Gerard of Cremona (11441187), described the heating of metals with various salts, which in the case of mercury resulted in the production of mercury(II) chloride (corrosive sublimate). In this process, hydrochloric acid actually started to form, but it immediately reacted with the mercury to produce corrosive sublimate. Thirteenth-century Latin alchemists, for whom the De aluminibus et salibus was one of the main reference works, were fascinated by the chlorinating properties of corrosive sublimate, and they soon discovered that when the metals are eliminated from the process of heating vitriols, alums, and salts, strong mineral acids can directly be distilled.

14th–15th century

Aqua regia
One important invention that resulted from the discovery of the mineral acids is aqua regia, a mixture of nitric acid and hydrochloric acid in a 1:3 proportion, capable of dissolving gold. This was first described in pseudo-Geber's De inventione veritatis ("On the Discovery of Truth", after ), where aqua regia was prepared by adding ammonium chloride to nitric acid. The fact that aqua regia typically is defined as a mixture of nitric acid and hydrochloric acid does not mean that hydrochloric acid was discovered before or simultaneously with aqua regia. The isolation of hydrochloric acid happened about 300 years later. The production of hydrochloric acid itself (i.e., as an isolated substance rather than as already mixed with nitric acid) depended on the use of more efficient cooling apparatus, which would only develop in subsequent centuries.

16th–17th century

Isolation of hydrochloric acid
From the point of view of Western history of chemistry, hydrochloric acid was the last of the three well-known mineral acids for which the method of its production appeared in the literature. Recipes for its production started to appear in the late sixteenth century. The earliest recipes for the production of hydrochloric acid are found in Giovanni Battista Della Porta's (1535–1615) Magiae naturalis ("Natural Magic") and in the works of other contemporary chemists like Andreas Libavius (–1616), Jean Beguin (1550–1620), and Oswald Croll (–1609). Among the historians who have written about this are German chemists Hermann Franz Moritz Kopp (1845) and Edmund Oscar von Lippmann (1938), mining engineer (and future U.S. president) Herbert Hoover with his wife geologist Lou Henry Hoover (1912), Dutch chemist Robert Jacobus Forbes (1948), American chemist Mary Elvira Weeks (1956), and British chemists F. Sherwood Taylor (1957) and J. R. Partington (1960). Italian chemist Ladislao Reti have summarized the result of their efforts thus:

Dissolving metals
The knowledge of mineral acids such as hydrochloric acid would be of key importance to seventeenth-century chemists like Daniel Sennert (1572–1637) and Robert Boyle (1627–1691), who used their capability to rapidly dissolve metals in their demonstrations of the composite nature of bodies.

Industrial developments
During the Industrial Revolution in Europe, demand for alkaline substances increased. A new industrial process developed by Nicolas Leblanc of Issoudun, France enabled cheap large-scale production of sodium carbonate (soda ash). In this Leblanc process, common salt is converted to soda ash, using sulfuric acid, limestone, and coal, releasing hydrogen chloride as a by-product. Until the British Alkali Act 1863 and similar legislation in other countries, the excess HCl was often vented into the air. An early exception was the Bonnington Chemical Works where, in 1830, the HCl began to be captured and the hydrochloric acid produced was used in making sal ammoniac (ammonium chloride). After the passage of the act, soda ash producers were obliged to absorb the waste gas in water, producing hydrochloric acid on an industrial scale.

In the 20th century, the Leblanc process was effectively replaced by the Solvay process without a hydrochloric acid by-product. Since hydrochloric acid was already fully settled as an important chemical in numerous applications, the commercial interest initiated other production methods, some of which are still used today. After 2000, hydrochloric acid is mostly made by absorbing by-product hydrogen chloride from industrial organic compounds production.

Chemical properties
Gaseous hydrogen chloride is a molecular compound with a covalent bond between the hydrogen and chlorine atoms. In aqueous solutions dissociation is complete, with the formation of chloride ions and hydrated hydrogen ions (hydronium ions). A combined IR, Raman, X-ray, and neutron diffraction study of concentrated hydrochloric acid showed that the hydronium ion forms hydrogen bonded complexes with other water molecules.  (See Hydronium for further discussion of this issue.)

The pKa value of hydrochloric acid in aqueous solution is estimated theoretically to be −5.9. A solution of hydrogen chloride in water behaves as a strong acid: the concentration of HCl molecules is effectively zero.

Physical properties

Physical properties of hydrochloric acid, such as boiling and melting points, density, and pH, depend on the concentration or molarity of HCl in the aqueous solution. They range from those of water at very low concentrations approaching 0% HCl to values for fuming hydrochloric acid at over 40% HCl.

Hydrochloric acid as the binary (two-component) mixture of HCl and H2O has a constant-boiling azeotrope at 20.2% HCl and . There are four constant-crystallization eutectic points for hydrochloric acid, between the crystal form of [H3O]Cl (68% HCl), [H5O2]Cl (51% HCl), [H7O3]Cl (41% HCl), [H3O]Cl·5H2O (25% HCl), and ice (0% HCl). There is also a metastable eutectic point at 24.8% between ice and the [H7O3]Cl crystallization. They are all hydronium salts.

Production
Hydrochloric acid is usually prepared industrially by dissolving hydrogen chloride in water. Hydrogen chloride can be generated in many ways, and thus several precursors to hydrochloric acid exist. The large-scale production of hydrochloric acid is almost always integrated with the industrial scale production of other chemicals, such as in the chloralkali process which produces hydroxide, hydrogen, and chlorine, the latter of which can be combined to produce HCl.

Hydrogen chloride is produced by combining chlorine and hydrogen:

Cl2 + H2 -> 2 HCl

As the reaction is exothermic, the installation is called an HCl oven or HCl burner. The resulting hydrogen chloride gas is absorbed in deionized water, resulting in chemically pure hydrochloric acid. This reaction can give a very pure product, e.g. for use in the food industry.

Industrial market
Hydrochloric acid is produced in solutions up to 38% HCl (concentrated grade). Higher concentrations up to just over 40% are chemically possible, but the evaporation rate is then so high that storage and handling require extra precautions, such as pressurization and cooling. Bulk industrial-grade is therefore 30% to 35%, optimized to balance transport efficiency and product loss through evaporation. In the United States, solutions of between 20% and 32% are sold as muriatic acid. Solutions for household purposes in the US, mostly cleaning, are typically 10% to 12%, with strong recommendations to dilute before use. In the United Kingdom, where it is sold as "Spirits of Salt" for domestic cleaning, the potency is the same as the US industrial grade. In other countries, such as Italy, hydrochloric acid for domestic or industrial cleaning is sold as "Acido Muriatico", and its concentration ranges from 5% to 32%.

Major producers worldwide include Dow Chemical at 2 million tonnes annually (Mt/year), calculated as HCl gas, Georgia Gulf Corporation, Tosoh Corporation, Akzo Nobel, and Tessenderlo at 0.5 to 1.5 Mt/year each. Total world production, for comparison purposes expressed as HCl, is estimated at 20 Mt/year, with 3 Mt/year from direct synthesis, and the rest as secondary product from organic and similar syntheses. By far, most hydrochloric acid is consumed captively by the producer. The open world market size is estimated at 5 Mt/year.

Applications

Hydrochloric acid is a strong inorganic acid that is used in many industrial processes such as refining metal. The application often determines the required product quality. Hydrogen chloride, not hydrochloric acid, is used more widely in industrial organic chemistry, e.g. for vinyl chloride and dichloroethane.

Pickling of steel
One of the most important applications of hydrochloric acid is in the pickling of steel, to remove rust or iron oxide scale from iron or steel before subsequent processing, such as extrusion, rolling, galvanizing, and other techniques. Technical quality HCl at typically 18% concentration is the most commonly used pickling agent for the pickling of carbon steel grades.
Fe3O4 + Fe + 8 HCl -> 4 FeCl2 + 4 H2O

The spent acid has long been reused as iron(II) chloride (also known as ferrous chloride) solutions, but high heavy-metal levels in the pickling liquor have decreased this practice.

The steel pickling industry has developed hydrochloric acid regeneration processes, such as the spray roaster or the fluidized bed HCl regeneration process, which allow the recovery of HCl from spent pickling liquor. The most common regeneration process is the pyrohydrolysis process, applying the following formula:
4 FeCl2 + 4 H2O + O2 -> 8 HCl + 2 Fe2O3

By recuperation of the spent acid, a closed acid loop is established. The iron(III) oxide by-product of the regeneration process is valuable, used in a variety of secondary industries.

Production of inorganic compounds
Akin to its use for pickling, hydrochloric acid is used to dissolve many metals, metal oxides and metal carbonates.  The conversions are often depicted in simplified equations:
 Zn + 2 HCl -> ZnCl2 + H2
 NiO + 2 HCl -> NiCl2 + H2O
 CaCO3 + 2 HCl -> CaCl2 + CO2 + H2
These processes are used to produce metal chlorides for analysis or further production.

pH control and neutralization
Hydrochloric acid can be used to regulate the acidity (pH) of solutions.
 HO- + HCl -> H2O + Cl-

In industry demanding purity (food, pharmaceutical, drinking water), high-quality hydrochloric acid is used to control the pH of process water streams. In less-demanding industry, technical quality hydrochloric acid suffices for neutralizing waste streams and swimming pool pH control.

Regeneration of ion exchangers
High-quality hydrochloric acid is used in the regeneration of ion exchange resins. Cation exchange is widely used to remove ions such as Na+ and Ca2+ from aqueous solutions, producing demineralized water. The acid is used to rinse the cations from the resins. Na+ is replaced with H+ and Ca2+ with 2 H+.

Ion exchangers and demineralized water are used in all chemical industries, drinking water production, and many food industries.

Laboratory use
Of the common strong mineral acids in chemistry, hydrochloric acid is the monoprotic acid least likely to undergo an interfering oxidation-reduction reaction. It is one of the least hazardous strong acids to handle; despite its acidity, it contains the non-reactive and non-toxic chloride ion. Intermediate-strength hydrochloric acid solutions are quite stable upon storage, maintaining their concentrations over time. These attributes, plus the fact that it is available as a pure reagent, make hydrochloric acid an excellent acidifying reagent. It is also inexpensive.

Hydrochloric acid is the preferred acid in titration for determining the amount of bases. Strong acid titrants give more precise results due to a more distinct endpoint. Azeotropic, or "constant-boiling", hydrochloric acid (roughly 20.2%) can be used as a primary standard in quantitative analysis, although its exact concentration depends on the atmospheric pressure when it is prepared.

Other
Hydrochloric acid is used for a large number of small-scale applications, such as leather processing, household cleaning, and building construction. Oil production may be stimulated by injecting hydrochloric acid into the rock formation of an oil well, dissolving a portion of the rock, and creating a large-pore structure. Oil well acidizing is a common process in the North Sea oil production industry.

Hydrochloric acid has been used for dissolving calcium carbonate, e.g. such things as de-scaling kettles and for cleaning mortar off brickwork. When used on brickwork the reaction with the mortar only continues until the acid has all been converted, producing calcium chloride, carbon dioxide, and water:
 CaCO3 + 2 HCl -> CaCl2 + CO2 + H2O

Many chemical reactions involving hydrochloric acid are applied in the production of food, food ingredients, and food additives. Typical products include aspartame, fructose, citric acid, lysine, hydrolyzed vegetable protein as food enhancer, and in gelatin production. Food-grade (extra-pure) hydrochloric acid can be applied when needed for the final product.

Presence in living organisms

Gastric acid is one of the main secretions of the stomach. It consists mainly of hydrochloric acid and acidifies the stomach content to a pH of 1 to 2. Chloride (Cl−) and hydrogen (H+) ions are secreted separately in the stomach fundus region at the top of the stomach by parietal cells of the gastric mucosa into a secretory network called canaliculi before it enters the stomach lumen.

Gastric acid acts as a barrier against microorganisms to prevent infections and is important for the digestion of food. Its low pH denatures proteins and thereby makes them susceptible to degradation by digestive enzymes such as pepsin. The low pH also activates the enzyme precursor pepsinogen into the active enzyme pepsin by self-cleavage. After leaving the stomach, the hydrochloric acid of the chyme is neutralized in the duodenum by bicarbonate.

The stomach itself is protected from the strong acid by the secretion of a thick mucus layer, and by secretin induced buffering with sodium bicarbonate. Heartburn or peptic ulcers can develop when these mechanisms fail. Drugs of the antihistaminic and proton pump inhibitor classes can inhibit the production of acid in the stomach, and antacids are used to neutralize excessive existing acid.

Safety

Being a strong acid, hydrochloric acid is corrosive to living tissue and to many materials, but not to rubber.  Typically, rubber protective gloves and related protective gear are used when handling concentrated solutions.

Legal status
Hydrochloric acid has been listed as a Table II precursor under the 1988 United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances because of its use in the production of heroin, cocaine, and methamphetamine.

See also
 Chloride, inorganic salts of hydrochloric acid
 Hydrochloride, organic salts of hydrochloric acid
 Aqua regia

References

External links

 NIST WebBook, general link
 Hydrochloric Acid – Part One and Hydrochloric Acid – Part Two at The Periodic Table of Videos (University of Nottingham)
 Calculators: surface tensions, and densities, molarities and molalities of aqueous HCl

General safety information
 EPA Hazard Summary
 Hydrochloric acid MSDS by Georgia Institute of Technology
 NIOSH Pocket Guide to Chemical Hazards

Pollution information
 National Pollutant Inventory – Hydrochloric Acid Fact Sheet

Mineral acids
Alchemical substances
Chlorides
Nonmetal halides
Photographic chemicals
Stomach
Solutions
E-number additives


Topiąca  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Września may refer to the following places:
Września in Greater Poland Voivodeship (west-central Poland)
Września, Masovian Voivodeship (east-central Poland)
Września, Świętokrzyskie Voivodeship (south-central Poland)


Września  is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Zamość () is a village in the administrative district of Gmina Rościszewo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south of Rościszewo,  east of Sierpc, and  north-west of Warsaw.

References

Villages in Sierpc County


Białe Błoto  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-east of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Białoskóry  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Białyszewo  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-east of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Białyszewo-Towarzystwo  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Bledzewko  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Bledzewko


Bledzewo  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south of Sierpc and  north-west of Warsaw.

References

Bledzewo


Borkowo Kościelne  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-east of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Borkowo Wielkie refers to the following places in Poland:

 Borkowo Wielkie, Masovian Voivodeship
 Borkowo Wielkie, West Pomeranian Voivodeship


Borkowo Wielkie  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-east of Sierpc and  north-west of Warsaw.

References

Borkowo Wielkie


Dąbrówki () is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-east of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Dębowo  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Dziembakowo  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-east of Sierpc and  north-west of Warsaw.

References

Dziembakowo


Goleszyn  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south of Sierpc and  north-west of Warsaw.

References

Goleszyn


Gorzewo  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Gorzewo


Grodkowo-Włóki  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Grodkowo-Zawisze  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south of Sierpc and  north-west of Warsaw.

References

Grodkowo-Zawisze


Karolewo  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Karolewo


Kisielewo  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-east of Sierpc and  north-west of Warsaw.

References

Kisielewo


Kręćkowo  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in East-Central Poland.

References

Villages in Sierpc County


Kwaśno  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Mieszaki  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-east of Sierpc and  north-west of Warsaw.

References

Mieszaki


Mieszczk  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Sierpc and  north-west of Warsaw. From 1975–1998, the town administratively belonged to the province of Plock.

References

Mieszczk


Miłobędzyn  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Nowe Piastowo  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Nowe Piastowo


Nowy Susk  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Nowy Susk


Osówka  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  west of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Pawłowo  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  west of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Piaski () is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south of Sierpc and  north-west of Warsaw.

References

Piaski


Podwierzbie  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Sierpc and  north-west of Warsaw.

References

Podwierzbie


Rachocin  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north of Sierpc and  north-west of Warsaw.

References

Rachocin


Rydzewo  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  west of Sierpc and  north-west of Warsaw.

References

Rydzewo


Stare Piastowo  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Stare Piastowo


Studzieniec  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Sierpc and  north-west of Warsaw.

References

Studzieniec


Sudragi  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Sierpc and  north-west of Warsaw.

References

Sudragi


Sułocin-Teodory  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Sułocin-Towarzystwo  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Susk  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south of Sierpc and  north-west of Warsaw.

References

Susk


Szczepanki  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-east of Sierpc and  north-west of Warsaw.

References

Szczepanki


Warzyn Kmiecy  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-east of Sierpc and  north-west of Warsaw.

References

Warzyn Kmiecy


Warzyn-Skóry  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Wernerowo  is a village in the administrative district of Gmina Sierpc within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Wernerowo


Wilczogóra  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Żochowo  is a village in the administrative district of Gmina Sierpc, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Mohamed Ahmed-Chamanga, is a Comorian linguistic, writer, researcher, politic and professor born in Ouani (Nzwani) in 1952.

He has worked mainly to make known his Comorian culture and in 2006 he was candidate for his country presidential election.

After his secondary studies, he graduated in Swahili and Arabic language and travelled to Madagascar and France where he made studies in linguistics. He created in 1976 a method to transcript Shikomori, and started writing articles about this language. He later published his thesis "Le Shindzuani (Comores) : Phonologie, morphologie, lexique" (1991) and has written many articles about Shikomori and transcribed Comorian tales.

He's currently teacher of Comorian at the Institut National des Langues et Civilisations Orientales (INALCO) in Paris, collaborator of Centre National de Documentation et de Recherche Scientifique (CNDRS, Moroni y Ouani) and professor at the University of Comoros since its creation.

References

Bibliography
 Dictionnaire français-comorien
 Lexique comorien (shindzuani)-français
 Contes comoriens de Ngazidja

External links
 Mohamed Ahmed-Chamanga: BiblioMonde
 Bibliographie
 Mohamed Ahmed-Chamanga candidat à l'élection présidentielle de 2006
 Site de l'INALCO
 L'Université des Comores

1952 births
Living people
Comorian politicians
Comorian writers
People from Anjouan


Agnieszkowo  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Szczutowo,  west of Sierpc, and  north-west of Warsaw.

References

Agnieszkowo


Białasy  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Blinno  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  west of Sierpc and  north-west of Warsaw.

References

Blinno


Blizno  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north-west of Sierpc and  north-west of Warsaw.

References

Blizno


Hoac, or variations, may refer to:

 An abbreviation of the chemical compound of Acetic acid
 HOAC, predecessor to Diamond Aircraft Industries
 Historians of American Communism, a scholarly historical organization established in 1982
 Hillingdon Outdoor Activity Centre, in the London Borough of Hillingdon


Całownia  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  west of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Dąbkowa Parowa  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north-west of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Dziki Bór () is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Gójsk  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Szczutowo,  west of Sierpc, and  north-west of Warsaw.

References

Villages in Sierpc County


Gorzeń  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north-east of Szczutowo,  north of Sierpc, and  north-west of Warsaw.

References

Villages in Sierpc County


Grabal  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  west of Szczutowo,  north-west of Sierpc, and  north-west of Warsaw.

References

Grabal


Grądy  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  west of Szczutowo,  west of Sierpc, and  north-west of Warsaw.

References

Villages in Sierpc County


Gugoły  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  east of Szczutowo,  north of Sierpc, and  north-west of Warsaw.

References

Villages in Sierpc County


Jaźwiny  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north-west of Sierpc and  north-west of Warsaw.

References

Villages in Sierpc County


Józefowo () is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Szczutowo,  west of Sierpc, and  north-west of Warsaw.

References

Villages in Sierpc County


Karlewo  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south of Szczutowo,  south of Sierpc, and  north-west of Warsaw.

References

Karlewo


Łazy  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Maluszyn  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Szczutowo,  west of Sierpc, and  north-west of Warsaw.

References

Maluszyn


Mierzęcin  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Modrzewie () is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Szczutowo,  west of Sierpc, and  north-west of Warsaw.

References

Modrzewie


Mościska  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Szczutowo,  west of Sierpc, and  north-west of Warsaw.

References

Villages in Sierpc County


Podlesie  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  west of Szczutowo,  west of Sierpc, and  north-west of Warsaw.

References

Podlesie


Słupia  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Stara Wola  is a village in the administrative district of Gmina Szczutowo, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Stara Wola


Szczutowo  is a village in Sierpc County, Masovian Voivodeship, in east-central Poland. It is the seat of the gmina (administrative district) called Gmina Szczutowo. It lies approximately  north-west of Sierpc and  north-west of Warsaw.

References

Szczutowo


A (US:) colter / (British:) coulter (Latin 'culter' = 'knife') is a vertically mounted component of many ploughs that cuts an edge about  deep ahead of a plowshare. Its most effective depth is determined by soil conditions.

History

Its earliest design consisted of a knife-like blade. In 2011 an early medieval coulter was excavated from a site in Kent, England. Coulters using a flat rotating disc began being used c. 1900. Its advantage was a smoothly cut bank, and it sliced plant debris to the width of the furrow.

Results
In his 1854 book, Henry Stephens used dynamometer measurements to conclude that a plough without a coulter took about the same amount of force to pull but using a coulter resulted in a much cleaner result. It softens the soil, allowing the plough to undercut the furrow made by the coulter.

Jointer

A rolling coulter has an optional accessory called a "jointer".  The jointer flips over a small part of the surface on top of the slice before the plowshare flips the main slice.  It ensures that all of the plant debris gets covered by the flipped slice.

References

Agricultural machinery
Ploughs


Budy Milewskie  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  east of Zawidz,  east of Sierpc, and  north-west of Warsaw.

References

External links
 Jewish Community in Budy Milewskie on Virtual Shtetl

Budy Milewskie


Budy Piaseczne  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  east of Zawidz,  east of Sierpc, and  north-west of Warsaw.

External links
 Jewish Community in Budy Piaseczne on Virtual Shtetl

References

Budy Piaseczne


Chabowo-Świniary  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Gołocin  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Grąbiec  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Grabowo  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north-west of Zawidz,  south-east of Sierpc, and  north-west of Warsaw.

References

Grabowo


Gutowo-Górki  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Gutowo-Stradzyno  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Gutowo-Stradzyno


Jaworowo-Jastrzębie  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north-east of Zawidz,  east of Sierpc, and  north-west of Warsaw.

References

Villages in Sierpc County


Jaworowo-Kłódź  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Jaworowo-Kolonia  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Jaworowo-Kolonia


Jaworowo-Lipa  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Jaworowo-Lipa


Jeżewo  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  west of Zawidz,  south-east of Sierpc, and  north-west of Warsaw.

References

Villages in Sierpc County


Kęsice  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  west of Zawidz,  south-east of Sierpc, and  north-west of Warsaw.

References

Villages in Sierpc County


Kosemin  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  north of Zawidz,  east of Sierpc, and  north-west of Warsaw.

References

Kosemin


Kosmaczewo  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south of Zawidz,  south-east of Sierpc, and  north-west of Warsaw.

References

Kosmaczewo


Krajewice Duże  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Zawidz,  south-east of Sierpc, and  north-west of Warsaw.

References

Villages in Sierpc County


Krajewice Małe  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  west of Zawidz,  south-east of Sierpc, and  north-west of Warsaw.

References

Villages in Sierpc County


Majki  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south of Zawidz,  south-east of Sierpc, and  north-west of Warsaw.

References

Majki


Majki Duże  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south of Zawidz,  south-east of Sierpc, and  north-west of Warsaw.

References

Villages in Sierpc County


Belu-Simion Fainaru (born 1959) is an Israeli sculptor who was born in Bucharest, Romania and immigrated to Israel in 1973.  He studied at the University of Haifa from 1980 to 1983 and earned an MA from the University of Chicago in 1984.  He continued his art education at the Domus Academy, Postgraduate School of Design in Milan, Italy and at The Royal Academies for Science and the Arts of Belgium in Brussels.  Fainaru lives and works in Haifa, Israel and in Antwerp, Belgium.

Much of Fainaru's work deals with Jewish history, Jewish rituals, and Jewish literature.

Biography
Belu Simion Fainaru, an Israeli sculptor and installation artist, was born in Bucharest, Romania in 1959 and in 1973 moved to Israel. During the 1980s, his work used motifs taken from Jewish culture, through which he raised questions of identity and historical memory. In his works, Fainaru created concretization of metaphysical concepts such as "light" or "name", into artistic objects that make use of the text.

Detachment, social issues and characters from the margins of Israeli society, are typical in many of Fainaru works. In the exhibit "The homeless" (1999), for example, Fainaru created a temporary living environment for the homeless in the art exhibition space. Fainaru also works as a curator. In 1993 he was the co-founder of the Pyramid organization in Haifa and in 2010 was one of the initiators and curators of "The Mediterranean Biennale".

Belu Simion Fainaru lives and works in Haifa.

Education
He attended Haifa University from 1980 to 1983 and obtained his MA in art from the University of Chicago in 1984. He also attended the Domus Academy in Milan and the Royal Academy of the Arts in Brussels.

Awards
 1985 Young Artist Award, Haifa Art Foundation, Haifa
 1987 Study scholarship from the Italian Government, Italy
 1989 Training Fellowship of the Belgian government, Belgium
 1991 Prize for a Young Artist, Ministry of Education
 1992 Sculpture Competition, Levi and Fortuna Askenazi Sculpture Garden, Tel Aviv University, First prize
 1994 The Nahum Gutman Prize for Painting and Sculpture, The Histadrut Labor Federation
 1997 George and Janet Jaffin Prize for Excellence in Plastic Arts, America-Israel Cultural Foundation
 2000 Aptowitzer Foundation Award for Distinguished Achievement in Contemporary Creative Arts, Haifa Museum of Art

References

Other sources
 Brockhaus, Christoph, Kulturräume, Skulptur seit 1970, Joseph Beuys, Belu-Simion Fainaru, Lutz Fritsch, Palle Seiersen Frost, Dani Karavan, Köln, DuMont, 1999, .

 Website Belu-Simion Fainaru
 The Mediterranean Biennale Belu-Simion Fainaru

Jewish sculptors
Israeli sculptors
Romanian Jews
Romanian emigrants to Israel
1959 births
Living people


Majki Małe  is a village in the administrative district of Gmina Zawidz, Sierpc County, Masovian Voivodeship, Poland. It lies approximately  south of Zawidz,  south-east of Sierpc, and  north-west of Warsaw.

References

Villages in Sierpc County


Hadacheck v. Sebastian, 239 U.S. 394 (1915), was an early U.S. Supreme Court case on the constitutionality of zoning ordinances.  The Court held that an ordinance of Los Angeles, California, prohibiting the manufacturing of bricks within specified limits of the city did not unconstitutionally deprive the petitioner of his property without due process of law, or deny him equal protection of the laws.

History

Los Angeles City Councilman Josias J. (Jerry) Andrews, one of the owners of the Victoria Park tract, moved the City Council to eliminate all brickyards in an area bounded by Wilshire Boulevard on the north, Western Avenue on the east, Washington Street on the south and the city limits on the west. That ordinance would effectively put two brickyards out of business, one of them just a few blocks west of Victoria Park, between Crenshaw Boulevard and Woolsey Avenue (today's Bronson Avenue) on Pico Street.

The Los Angeles Times said that the brickyard "happens to be in a district where Andrews now has large real estate investments. . . . The ordinance was calculated to drive out of business a brickyard facing Victoria Park." The Times opined that the purpose of the law was "to free that ornate neighborhood [Victoria Park] of the unsightly and unesthetic brickyards. Andrews admitted a 'small' interest in the tract but vehemently declared [that] his private interests could have no influence on his duty to the people who are oppressed by the brickyards that were there before real estate agents developed new tracts.

The city law was approved by the council, vetoed by Mayor George Alexander and passed over the mayor's veto. Because of the new law, the owner of one of the yards, J.C. Hadacheck, was convicted of a misdemeanor for the violation of a city ordinance, which prohibited the establishment or operation a brickyard or brick kiln, or any manufacture or burning of brick within described limits in the city.  Hadacheck was taken into custody by Los Angeles Chief of Police Charles E. Sebastian, whereupon he filed a petition for habeas corpus with the California Supreme Court.

California Supreme Court

In his petition to the court, Hadacheck (who had acquired his property prior to his district's annexation by the city of Los Angeles) set forth at length his grievances with the ordinance and the decision of the lower court, including inter alia (among other things) that his land contained valuable deposits of clay which were ideal for making bricks, that his land was quite valuable and that he acquired this particular tract for the express purpose of manufacturing bricks, that the ordinance would deprive him of his use of the property and force him to abandon his business, that his business was conducted in such a manner as to emit as little pollution as possible and could not be considered a nuisance under the California Civil Code, and that the district described by the ordinance was drawn in such a manner solely to disrupt his business.  Hadacheck further alleged an unconstitutional taking by the city, and that the ordinance violated both the California Constitution and the Fourteenth Amendment to the United States Constitution.

The California Supreme Court found in favor of the city, accepting the judgment of the legislators.  The court held that the business was one which could be lawfully regulated, and the fact that the petitioner began his business prior to the enactment of the ordinance was no defense.  The court also discussed the affidavits submitted by interested parties which contradicted Hadacheck's assertions that the business was conducted in a sanitary, non-polluting manner.

U.S. Supreme Court decision
Justice McKenna, writing for a unanimous court, upheld the California Supreme Court's decision, holding that the ordinance was a legitimate use of the police power.  He analogized this case to an earlier one, Reinman v. Little Rock, which dealt with a similar ordinance banning livery stables.  Reinman was distinguishable on the grounds that a livery stable could be moved and operated anywhere, while bricks can only be manufactured where suitable clay is found.  Hadacheck contended that the removal of clay from his land was not physically impossible, but was prohibitively expensive.  The Court held that even though relocating the brick factory would be costly, the ordinance did not amount to a complete denial of the use of Hadacheck's property, because the ordinance did not completely deny Hadacheck the use of the clay on his land.

The Court further held that the ordinance did not violate the Equal Protection Clause of the Fourteenth Amendment.  Hadacheck alleged that his business was prohibited while those of his competitors elsewhere were not.  The Court responded that just because his business was the first to be shut down, it does not follow that others would not be in the future, thus this issue was beyond the scope of the case.

Historical importance
Hadacheck v. Sebastian was one of the first cases to deal with the issue of regulatory takings under zoning laws, even though the ordinance in question was simple and primitive in comparison to modern American zoning schemes.  Because of this, the case is commonly discussed in first year constitutional law and/or property law classes in American law schools.

Notes and references
Access to some of the links may require the use of a library card.

External links

Excerpt from Environment, Property and Law by Ronald H. Rosenberg, courtesy of Google Book Search

United States Supreme Court cases
United States Supreme Court cases of the White Court
United States equal protection case law
United States land use case law
United States substantive due process case law
1915 in the environment
1915 in United States case law


Makomazy  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland. It lies approximately  south-west of Zawidz,  south-east of Sierpc, and  north-west of Warsaw.

References

Makomazy


Mańkowo  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Villages in Sierpc County


Milewko  is a village in the administrative district of Gmina Zawidz, within Sierpc County, Masovian Voivodeship, in east-central Poland.

References

Milewko