1.
Oxygen
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Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the group on the periodic table and is a highly reactive nonmetal. By mass, oxygen is the third-most abundant element in the universe, after hydrogen, at standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. This is an important part of the atmosphere and diatomic oxygen gas constitutes 20. 8% of the Earths atmosphere, additionally, as oxides the element makes up almost half of the Earths crust. Most of the mass of living organisms is oxygen as a component of water, conversely, oxygen is continuously replenished by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. Oxygen is too reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. Another form of oxygen, ozone, strongly absorbs ultraviolet UVB radiation, but ozone is a pollutant near the surface where it is a by-product of smog. At low earth orbit altitudes, sufficient atomic oxygen is present to cause corrosion of spacecraft, the name oxygen was coined in 1777 by Antoine Lavoisier, whose experiments with oxygen helped to discredit the then-popular phlogiston theory of combustion and corrosion. One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium. In his work Pneumatica, Philo observed that inverting a vessel over a burning candle, Philo incorrectly surmised that parts of the air in the vessel were converted into the classical element fire and thus were able to escape through pores in the glass. Many centuries later Leonardo da Vinci built on Philos work by observing that a portion of air is consumed during combustion and respiration, Oxygen was discovered by the Polish alchemist Sendivogius, who considered it the philosophers stone. In the late 17th century, Robert Boyle proved that air is necessary for combustion, English chemist John Mayow refined this work by showing that fire requires only a part of air that he called spiritus nitroaereus. From this he surmised that nitroaereus is consumed in both respiration and combustion, Mayow observed that antimony increased in weight when heated, and inferred that the nitroaereus must have combined with it. Accounts of these and other experiments and ideas were published in 1668 in his work Tractatus duo in the tract De respiratione. Robert Hooke, Ole Borch, Mikhail Lomonosov, and Pierre Bayen all produced oxygen in experiments in the 17th and the 18th century but none of them recognized it as a chemical element. This may have been in part due to the prevalence of the philosophy of combustion and corrosion called the phlogiston theory, which was then the favored explanation of those processes. Established in 1667 by the German alchemist J. J. Becher, one part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, or calx. The fact that a substance like wood gains overall weight in burning was hidden by the buoyancy of the combustion products
2.
Linus Pauling
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Linus Carl Pauling was an American chemist, biochemist, peace activist, author, and educator. He published more than 1,200 papers and books, of which about 850 dealt with scientific topics, new Scientist called him one of the 20 greatest scientists of all time, and as of 2000, he was rated the 16th most important scientist in history. Pauling was one of the founders of the fields of quantum chemistry, for his scientific work, Pauling was awarded the Nobel Prize in Chemistry in 1954. In 1962, for his activism, he was awarded the Nobel Peace Prize. This makes him the person to be awarded two unshared Nobel Prizes. He is one of four individuals to have won more than one Nobel Prize. Pauling is also one of two people to be awarded Nobel Prizes in different fields, the other being Marie Curie. Pauling also worked on DNAs structure, a problem which was solved by James Watson, Francis Crick, Rosalind Franklin, in his later years he promoted nuclear disarmament, as well as orthomolecular medicine, megavitamin therapy, and dietary supplements. None of the latter have gained acceptance in the scientific community. Pauling was born in Portland, Oregon, the child of Herman Henry William Pauling. He was named Linus Carl, in honor of Lucys father, Linus, in 1902, after his sister Pauline was born, Paulings parents decided to move out of Portland, to find more affordable and spacious living quarters than their one-room apartment. Lucy stayed with her husbands parents in Lake Oswego until Herman brought the family to Salem, within a year of Luciles birth in 1904, Herman Pauling moved his family to Oswego, where he opened his own drugstore. He moved his family to Condon, Oregon in 1905, by 1906, Herman Pauling was suffering from recurrent abdominal pain. He died of an ulcer on June 11,1910, leaving Lucy to care for Linus, Lucile. Pauling attributes his interest in becoming a chemist to being amazed by experiments conducted by a friend, Lloyd A. Jeffress, in high school, Pauling conducted chemistry experiments by scavenging equipment and material from an abandoned steel plant. With an older friend, Lloyd Simon, Pauling set up Palmon Laboratories in Simons basement and they approached local dairies offering to perform butterfat samplings at cheap prices but dairymen were wary of trusting two boys with the task, and the business ended in failure. At age 15, the high school senior had enough credits to enter Oregon State University, lacking two American history courses required for his high school diploma, Pauling asked the school principal if he could take the courses concurrently during the spring semester. Denied, he left Washington High School in June without a diploma, the school awarded him a diploma 45 years later, after he had won two Nobel Prizes
3.
Water
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Water is a transparent and nearly colorless chemical substance that is the main constituent of Earths streams, lakes, and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that its molecule contains one oxygen, Water strictly refers to the liquid state of that substance, that prevails at standard ambient temperature and pressure, but it often refers also to its solid state or its gaseous state. It also occurs in nature as snow, glaciers, ice packs and icebergs, clouds, fog, dew, aquifers, Water covers 71% of the Earths surface. It is vital for all forms of life. Only 2. 5% of this water is freshwater, and 98. 8% of that water is in ice and groundwater. Less than 0. 3% of all freshwater is in rivers, lakes, and the atmosphere, a greater quantity of water is found in the earths interior. Water on Earth moves continually through the cycle of evaporation and transpiration, condensation, precipitation. Evaporation and transpiration contribute to the precipitation over land, large amounts of water are also chemically combined or adsorbed in hydrated minerals. Safe drinking water is essential to humans and other even though it provides no calories or organic nutrients. There is a correlation between access to safe water and gross domestic product per capita. However, some observers have estimated that by 2025 more than half of the population will be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in developing regions of the world. Water plays an important role in the world economy, approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a source of food for many parts of the world. Much of long-distance trade of commodities and manufactured products is transported by boats through seas, rivers, lakes, large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a variety of chemical substances, as such it is widely used in industrial processes. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, Water is a liquid at the temperatures and pressures that are most adequate for life. Specifically, at atmospheric pressure of 1 bar, water is a liquid between the temperatures of 273.15 K and 373.15 K
4.
Sulfuric acid
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Sulfuric acid is a highly corrosive strong mineral acid with the molecular formula H2SO4 and molecular weight 98.079 g/mol. It is a pungent-ethereal, colorless to slightly yellow liquid that is soluble in water at all concentrations. Sometimes, it is dyed dark brown during production to alert people to its hazards, the historical name of this acid is oil of vitriol. Sulfuric acid is an acid and shows different properties depending upon its concentration. Its corrosiveness on other materials, like metals, living tissues or even stones, can be ascribed to its strong acidic nature and, if concentrated. It is also hygroscopic, readily absorbing water vapour from the air, Sulfuric acid at a high concentration can cause very serious damage upon contact, since not only does it cause chemical burns via hydrolysis, but also secondary thermal burns through dehydration. It can lead to permanent blindness if splashed onto eyes and irreversible damage if swallowed, Sulfuric acid has a wide range of applications including in domestic acidic drain cleaners, as an electrolyte in lead-acid batteries and in various cleaning agents. It is also a central substance in the chemical industry, principal uses include mineral processing, fertilizer manufacturing, oil refining, wastewater processing, and chemical synthesis. It is widely produced with different methods, such as process, wet sulfuric acid process, lead chamber process. The study of vitriol, a category of glassy minerals from which the acid can be derived, sumerians had a list of types of vitriol that they classified according to the substances color. Some of the earliest discussions on the origin and properties of vitriol is in the works of the Greek physician Dioscorides, galen also discussed its medical use. Ibn Sina focused on its uses and different varieties of vitriol. Sulfuric acid was called oil of vitriol by medieval European alchemists because it was prepared by roasting green vitriol in an iron retort, there are references to it in the works of Vincent of Beauvais and in the Compositum de Compositis ascribed to Saint Albertus Magnus. A passage from Pseudo-Geber´s Summa Perfectionis was long considered to be the first recipe for sulfuric acid, in the seventeenth century, the German-Dutch chemist Johann Glauber prepared sulfuric acid by burning sulfur together with saltpeter, in the presence of steam. As saltpeter decomposes, it oxidizes the sulfur to SO3, in 1736, Joshua Ward, a London pharmacist, used this method to begin the first large-scale production of sulfuric acid. This process allowed the effective industrialization of sulfuric acid production, after several refinements, this method, called the lead chamber process or chamber process, remained the standard for sulfuric acid production for almost two centuries. Sulfuric acid created by John Roebucks process approached a 65% concentration, later refinements to the lead chamber process by French chemist Joseph Louis Gay-Lussac and British chemist John Glover improved concentration to 78%. However, the manufacture of dyes and other chemical processes require a more concentrated product
5.
American and British English spelling differences
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Many of the differences between American and British English date back to a time when spelling standards had not yet developed. For instance, some spellings seen as American today were once used in Britain. But English-language spelling reform has rarely been adopted otherwise, and thus modern English orthography varies somewhat between countries and is far from phonemic in any country, in the early 18th century, English spelling was inconsistent. These differences became noticeable after the publishing of influential dictionaries, todays British English spellings mostly follow Johnsons A Dictionary of the English Language, while many American English spellings follow Websters An American Dictionary of the English Language. Webster was a proponent of English spelling reform for reasons both philological and nationalistic, in A Companion to the American Revolution, John Algeo notes, it is often assumed that characteristically American spellings were invented by Noah Webster. He was very influential in popularizing certain spellings in America, rather he chose already existing options such as center, color and check for the simplicity, analogy or etymology. William Shakespeares first folios, for example, used spellings like center and color as much as centre, Webster did attempt to introduce some reformed spellings, as did the Simplified Spelling Board in the early 20th century, but most were not adopted. In Britain, the influence of those who preferred the Norman spellings of words proved to be decisive, later spelling adjustments in the United Kingdom had little effect on todays American spellings and vice versa. For the most part, the systems of most Commonwealth countries. Australian spelling has also strayed slightly from British spelling, with some American spellings incorporated as standard, New Zealand spelling is almost identical to British spelling, except in the word fiord. There is also an increasing use of macrons in words that originated in Māori, most words ending in an unstressed -our in British English end in -or in American English. Wherever the vowel is unreduced in pronunciation, e. g. contour, velour, paramour and troubadour the spelling is the same everywhere, most words of this kind came from Latin, where the ending was spelled -or. They were first adopted into English from early Old French, after the Norman conquest of England, the ending became -our to match the Old French spelling. The -our ending was not only used in new English borrowings, however, -or was still sometimes found, and the first three folios of Shakespeares plays used both spellings before they were standardised to -our in the Fourth Folio of 1685. After the Renaissance, new borrowings from Latin were taken up with their original -or ending, Websters 1828 dictionary had only -or and is given much of the credit for the adoption of this form in the United States. Johnson, unlike Webster, was not an advocate of spelling reform and he preferred French over Latin spellings because, as he put it, the French generally supplied us. In Jeffersons original draft it is spelled honour, Honor and honour were equally frequent in Britain until the 17th century, honor still is, in the UK, the usual spelling as a persons name and appears in Honor Oak, a district of London. In derivatives and inflected forms of the words, British usage depends on the nature of the suffix used
6.
Conjugate acid
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A conjugate acid, within the Brønsted–Lowry acid–base theory, is a species formed by the reception of a proton by a base—in other words, it is a base with a hydrogen ion added to it. On the other hand, a base is merely what is left after an acid has donated a proton in a chemical reaction. Hence, a base is a species formed by the removal of a proton from an acid. A proton is a particle with a unit positive electrical charge, it is represented by the symbol H+ because it constitutes the nucleus of a hydrogen atom, that is. A cation can be an acid, and an anion can be a conjugate base, depending on which substance is involved. In an acid-base reaction, an acid plus a base reacts to form a conjugate base plus a conjugate acid, refer to the following figure, We say that the water molecule is the conjugate acid of the hydroxide ion after the latter received the hydrogen proton donated by ammonium. On the other hand, ammonia is the base for the acid ammonium after ammonium has donated a hydrogen ion towards the production of the water molecule. The strength of an acid is directly proportional to its dissociation constant. If a conjugate acid is strong, its dissociation will have an equilibrium constant. The strength of a base can be seen as the tendency of the species to pull hydrogen protons towards itself. If a conjugate base is classified as strong, it will hold on to the hydrogen proton when in solution, if a chemical species is classified as a weak acid, its conjugate base will be strong in nature. This can be observed in ammonias reaction with water, the reaction proceeds until most of the ammonia has been transformed to ammonium. This shift to the right in the equilibrium of the reaction means that ammonium does not dissociate easily in water. On the other hand, if a species is classified as a strong acid, an example of this case would be the dissociation of Hydrochloric acid HCl in water. Since HCl is an acid, its conjugate base will be a weak conjugate base. Therefore, in system, most H+ will be in the form of a Hydronium ion H 3O+ instead of attached to a Cl anion. To summarize, the stronger the acid or base, the weaker the conjugate, the acid and conjugate base as well as the base and conjugate acid are known as conjugate pairs. When finding a conjugate acid or base, it is important to look at the reactants of the chemical equation, to identify the conjugate acid, look for the pair of compounds that are related
7.
Salt (chemistry)
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In chemistry, a salt is an ionic compound that results from the neutralization reaction of an acid and a base. Salts are composed of related numbers of cations and anions so that the product is electrically neutral and these component ions can be inorganic, such as chloride, or organic, such as acetate, and can be monatomic, such as fluoride, or polyatomic, such as sulfate. There are several varieties of salts, salts that hydrolyze to produce hydroxide ions when dissolved in water are alkali salts, whilst those that hydrolyze to produce hydronium ions in water are acidic salts. Neutral salts are those salts that are neither acidic nor basic, zwitterions contain an anionic centre and a cationic centre in the same molecule, but are not considered to be salts. Examples of zwitterions include amino acids, many metabolites, peptides, usually, non-dissolved salts at standard conditions for temperature and pressure are solid, but there are exceptions. Molten salts and solutions containing dissolved salts are called electrolytes, as they are able to conduct electricity. As observed in the cytoplasm of cells, in blood, urine, plant saps and mineral waters, therefore, their salt content is given for the respective ions. Salts can appear to be clear and transparent, opaque, and even metallic, in many cases, the apparent opacity or transparency are only related to the difference in size of the individual monocrystals. Since light reflects from the boundaries, larger crystals tend to be transparent. The color of the salt is due to the electronic structure in the d-orbitals of transition elements or in the conjugated organic dye framework. Different salts can elicit all five basic tastes, e. g. salty, sweet, sour, bitter, and umami or savory. Salts of strong acids and strong bases are non-volatile and odorless and that slow, partial decomposition is usually accelerated by the presence of water, since hydrolysis is the other half of the reversible reaction equation of formation of weak salts. Many ionic compounds can be dissolved in water or other similar solvents, the exact combination of ions involved makes each compound have a unique solubility in any solvent. The solubility is dependent on how well each ion interacts with the solvent, for example, all salts of sodium, potassium and ammonium are soluble in water, as are all nitrates and many sulfates – barium sulfate, calcium sulfate and lead sulfate are examples of exceptions. However, ions that bind tightly to each other and form highly stable lattices are less soluble, for example, most carbonate salts are not soluble in water, such as lead carbonate and barium carbonate. Some soluble carbonate salts are, sodium carbonate, potassium carbonate, solid salts do not conduct electricity. Moreover, solutions of salts also conduct electricity, the name of a salt starts with the name of the cation followed by the name of the anion. Salts are often referred to only by the name of the cation or by the name of the anion. g
8.
Jmol
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Jmol is computer software for molecular modelling chemical structures in 3-dimensions. Jmol returns a 3D representation of a molecule that may be used as a teaching tool and it is written in the programming language Java, so it can run on the operating systems Windows, macOS, Linux, and Unix, if Java is installed. It is free and open-source software released under a GNU Lesser General Public License version 2.0, a standalone application and a software development kit exist that can be integrated into other Java applications, such as Bioclipse and Taverna. A popular feature is an applet that can be integrated into web pages to display molecules in a variety of ways, for example, molecules can be displayed as ball-and-stick models, space-filling models, ribbon diagrams, etc. Jmol supports a range of chemical file formats, including Protein Data Bank, Crystallographic Information File, MDL Molfile. There is also a JavaScript-only version, JSmol, that can be used on computers with no Java, the Jmol applet, among other abilities, offers an alternative to the Chime plug-in, which is no longer under active development. While Jmol has many features that Chime lacks, it does not claim to reproduce all Chime functions, most notably, Chime requires plug-in installation and Internet Explorer 6.0 or Firefox 2.0 on Microsoft Windows, or Netscape Communicator 4.8 on Mac OS9. Jmol requires Java installation and operates on a variety of platforms. For example, Jmol is fully functional in Mozilla Firefox, Internet Explorer, Opera, Google Chrome, fast and Scriptable Molecular Graphics in Web Browsers without Java3D
9.
Tetrahedron
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In geometry, a tetrahedron, also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the ordinary convex polyhedra, the tetrahedron is the three-dimensional case of the more general concept of a Euclidean simplex. The tetrahedron is one kind of pyramid, which is a polyhedron with a polygon base. In the case of a tetrahedron the base is a triangle, like all convex polyhedra, a tetrahedron can be folded from a single sheet of paper. For any tetrahedron there exists a sphere on which all four vertices lie, a regular tetrahedron is one in which all four faces are equilateral triangles. It is one of the five regular Platonic solids, which have known since antiquity. In a regular tetrahedron, not only are all its faces the same size and shape, regular tetrahedra alone do not tessellate, but if alternated with regular octahedra they form the alternated cubic honeycomb, which is a tessellation. The regular tetrahedron is self-dual, which means that its dual is another regular tetrahedron, the compound figure comprising two such dual tetrahedra form a stellated octahedron or stella octangula. This form has Coxeter diagram and Schläfli symbol h, the tetrahedron in this case has edge length 2√2. Inverting these coordinates generates the dual tetrahedron, and the together form the stellated octahedron. In other words, if C is the centroid of the base and this follows from the fact that the medians of a triangle intersect at its centroid, and this point divides each of them in two segments, one of which is twice as long as the other. The vertices of a cube can be grouped into two groups of four, each forming a regular tetrahedron, the symmetries of a regular tetrahedron correspond to half of those of a cube, those that map the tetrahedra to themselves, and not to each other. The tetrahedron is the only Platonic solid that is not mapped to itself by point inversion, the regular tetrahedron has 24 isometries, forming the symmetry group Td, isomorphic to the symmetric group, S4. The first corresponds to the A2 Coxeter plane, the two skew perpendicular opposite edges of a regular tetrahedron define a set of parallel planes. When one of these intersects the tetrahedron the resulting cross section is a rectangle. When the intersecting plane is one of the edges the rectangle is long. When halfway between the two edges the intersection is a square, the aspect ratio of the rectangle reverses as you pass this halfway point. For the midpoint square intersection the resulting boundary line traverses every face of the tetrahedron similarly, if the tetrahedron is bisected on this plane, both halves become wedges
10.
Calcium sulfate
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Calcium sulfate is the inorganic compound with the formula CaSO4 and related hydrates. In the form of γ-anhydrite, it is used as a desiccant, one particular hydrate is better known as plaster of Paris, and another occurs naturally as the mineral gypsum. It has many uses in industry, all forms are white solids that are poorly soluble in water. Calcium sulfate causes permanent hardness in water, the compound exists in three levels of hydration, anhydrous state with the formula CaSO4. Specific hemihydrates are sometimes distinguished, alpha-hemihydrate and beta-hemihydrate, the main use of calcium sulfate is to produce Plaster of Paris and stucco. These applications exploit the fact that calcium sulfate forms a moldable paste upon hydration and it is also convenient that calcium sulfate is very poorly soluble in water, so structures do not dissolve. Temperatures between 100 °C and 150 °C are required to drive off the water within its structure, the details of the temperature and time depend on ambient humidity. Temperatures as high as 170 °C are used in industrial calcination, in a fire, the structure behind a sheet of drywall will remain relatively cool as water is lost from the gypsum, thus preventing damage to the framing and consequent structural collapse. But at higher temperatures, calcium sulfate will release oxygen and act as an oxidizing agent and this property is used in aluminothermy. Mixed with polymers, it has used as a bone repair cement. Small amounts of calcined gypsum are added to earth to create strong structures directly from cast earth, the conditions of dehydration can be changed to adjust the porosity of the hemihydrate, resulting in the so-called alpha and beta hemihydrates. On heating to 180 °C, the nearly water-free form, called γ-anhydrite is produced, γ-Anhydrite reacts slowly with water to return to the dihydrate state, a property exploited in some commercial desiccants. On heating above 250 °C, the anhydrous form called β-anhydrite or natural anhydrite is formed. Natural anhydrite does not react with water, even over geological timescales, the hydrates are used as a coagulant in products such as tofu. Up to the 1970s, commercial quantities of sulfuric acid were produced from the anhydride of calcium sulfate, when sold as a color-indicating variant under the name Drierite, it appears blue or pink due to impregnation with cobalt chloride, which functions as a moisture indicator. The main sources of sulfate are naturally occurring gypsum and anhydrite. These may be extracted by open-cast quarrying or by deep mining, world production of natural gypsum is around 127 million tonnes per annum. This produces an impure calcium sulfite, which oxidizes on storage to calcium sulfate, in the production of phosphoric acid from phosphate rock, calcium phosphate is treated with sulfuric acid and calcium sulfate precipitates
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