1.
Copper
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Copper is a chemical element with symbol Cu and atomic number 29. It is a soft, malleable, and ductile metal with high thermal and electrical conductivity. A freshly exposed surface of copper has a reddish-orange color. Copper is one of the few metals that occur in nature in directly usable metallic form as opposed to needing extraction from an ore and this led to very early human use, from c.8000 BC. Copper used in buildings, usually for roofing, oxidizes to form a green verdigris, Copper is sometimes used in decorative art, both in its elemental metal form and in compounds as pigments. Copper compounds are used as agents, fungicides, and wood preservatives. Copper is essential to all living organisms as a trace dietary mineral because it is a key constituent of the enzyme complex cytochrome c oxidase. In molluscs and crustaceans, copper is a constituent of the blood pigment hemocyanin, replaced by the hemoglobin in fish. In humans, copper is found mainly in the liver, muscle, the adult body contains between 1.4 and 2.1 mg of copper per kilogram of body weight. The filled d-shells in these elements contribute little to interatomic interactions, unlike metals with incomplete d-shells, metallic bonds in copper are lacking a covalent character and are relatively weak. This observation explains the low hardness and high ductility of single crystals of copper, at the macroscopic scale, introduction of extended defects to the crystal lattice, such as grain boundaries, hinders flow of the material under applied stress, thereby increasing its hardness. For this reason, copper is supplied in a fine-grained polycrystalline form. The softness of copper partly explains its high conductivity and high thermal conductivity. The maximum permissible current density of copper in open air is approximately 3. 1×106 A/m2 of cross-sectional area, Copper is one of a few metallic elements with a natural color other than gray or silver. Pure copper is orange-red and acquires a reddish tarnish when exposed to air, as with other metals, if copper is put in contact with another metal, galvanic corrosion will occur. A green layer of verdigris can often be seen on old structures, such as the roofing of many older buildings. Copper tarnishes when exposed to sulfur compounds, with which it reacts to form various copper sulfides. There are 29 isotopes of copper, 63Cu and 65Cu are stable, with 63Cu comprising approximately 69% of naturally occurring copper, both have a spin of 3⁄2
2.
Zinc
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Zinc is a chemical element with the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table, in some respects zinc is chemically similar to magnesium, both elements exhibit only one normal oxidation state, and the Zn2+ and Mg2+ ions are of similar size. Zinc is the 24th most abundant element in Earths crust and has five stable isotopes, the most common zinc ore is sphalerite, a zinc sulfide mineral. The largest workable lodes are in Australia, Asia, and the United States, Zinc is refined by froth flotation of the ore, roasting, and final extraction using electricity. Zinc metal was not produced on a large scale until the 12th century in India and was unknown to Europe until the end of the 16th century, the mines of Rajasthan have given definite evidence of zinc production going back to the 6th century BC. To date, the oldest evidence of pure zinc comes from Zawar, in Rajasthan, alchemists burned zinc in air to form what they called philosophers wool or white snow. The element was named by the alchemist Paracelsus after the German word Zinke. German chemist Andreas Sigismund Marggraf is credited with discovering pure metallic zinc in 1746, work by Luigi Galvani and Alessandro Volta uncovered the electrochemical properties of zinc by 1800. Corrosion-resistant zinc plating of iron is the application for zinc. Other applications are in batteries, small non-structural castings. A variety of compounds are commonly used, such as zinc carbonate and zinc gluconate, zinc chloride, zinc pyrithione, zinc sulfide. Zinc is an essential mineral perceived by the public today as being of exceptional biologic and public health importance, Zinc deficiency affects about two billion people in the developing world and is associated with many diseases. In children, deficiency causes growth retardation, delayed sexual maturation, infection susceptibility, enzymes with a zinc atom in the reactive center are widespread in biochemistry, such as alcohol dehydrogenase in humans. Consumption of excess zinc can cause ataxia, lethargy and copper deficiency, Zinc is a bluish-white, lustrous, diamagnetic metal, though most common commercial grades of the metal have a dull finish.6 pm. The metal is hard and brittle at most temperatures but becomes malleable between 100 and 150 °C, above 210 °C, the metal becomes brittle again and can be pulverized by beating. Zinc is a conductor of electricity. For a metal, zinc has relatively low melting and boiling points, the melting point is the lowest of all the transition metals aside from mercury and cadmium. Many alloys contain zinc, including brass, Other metals long known to form binary alloys with zinc are aluminium, antimony, bismuth, gold, iron, lead, mercury, silver, tin, magnesium, cobalt, nickel, tellurium, and sodium
3.
Tempio Voltiano
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The Tempio Voltiano is a museum in the city of Como, Italy that is dedicated to Alessandro Volta, a prolific scientist and the inventor of the electrical battery. Volta was born in Como in 1745, held his first professorship there until 1779, the neoclassical building was designed by Federico Frigerio. It was completed in 1927 to celebrate the 100th anniversary of the scientists death and it hosts a collection of scientific instruments used by the physicist including his early voltaic piles. The first floor has a display of his belongings and his awards. It is one of the most visited museums in town, the temple was featured on the back of the 10,000 lire banknote, while Voltas portrait was depicted on the front of the same banknote. Banknotes based on the Italian lira have since replaced by notes denominated in Euros. In the nearbies of the Tempio Voltiano, there are the new statue of Daniel Libeskind named Life Electric, musei Civici di Como - Tempio Voltiano. The Geek Atlas,128 Places Where Science and Technology Come Alive
4.
Como
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Como is a city and comune in Lombardy, Italy. It is the capital of the Province of Como. With 215,320 overnight guests, in 2013 Como was the fourth most visited city in Lombardy after Milan, Bergamo, the hills surrounding the current location of Como have been inhabited, since at least the Bronze Age, by a Celtic tribe known as the Orobii. Remains of settlements are still present on the wood covered hills to the South West of town, around the 1st century BC, the territory became subject to the Romans. The newly founded town was named Novum Comum and had the status of municipium, in 774, the town surrendered to invading Franks led by Charlemagne, and became a center of commercial exchange. In 1127, Como lost a war with the nearby town of Milan. A few decades later, with the help of Frederick Barbarossa, Frederick promoted the construction of several defensive towers around the city limits, of which only one, the Baradello, remains. Subsequently, the history of Como followed that of the Ducato di Milano, through the French invasion and the Spanish domination, until 1714, Napoleon descended into Lombardy in 1796 and ruled it until 1815, when the Austrian rule was resumed after the Congress of Vienna. Finally in 1859, with the arrival of Giuseppe Garibaldi, the town was freed from the Austrians, as a curiosity, the Rockefeller fountain that today stands in the Bronx Zoo in New York City was once in the main square by the lakeside. It was bought by William Rockefeller in 1902 for 3,500 lire, nearby major cities are Varese, Lecco and Lugano. Wind is quite rare, only sudden bursts of foehn or thunderstorms manage to sweep the air clean, pollution levels rise significantly in winter when cold air clings to the soil. Rain is more frequent during spring, summer is subject to thunderstorms and, occasionally, Como Cathedral, construction began in 1396 on the site of the previous Romanesque church of Santa Maria Maggiore. The façade was built in 1457, with the rose window. The construction was finished in 1740, the interior is on the Latin cross plan, with Gothic nave and two aisles divided by piers, while the transept wing and the relative apses are from the Renaissance age. It includes a carved 16th century choir and tapestries on cartoons by Giuseppe Arcimboldi, the dome is a rococo structure by Filippo Juvarra. Other artworks include 16th–17th century tapestries and 16th century paintings by Bernardino Luini, San Fedele, a Romanesque church erected around 1120 over a pre-existing central plan edifice. The original bell tower was rebuilt in modern times, the main feature is the famous Door of St. Fedele, carved with medieval decorations. SantAgostino, built by the Cistercians in the early 14th century, the interior and adjoining cloister have 15th–17th century frescoes, but most of the decoration is Baroque
5.
Battery (electricity)
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An electric battery is a device consisting of one or more electrochemical cells with external connections provided to power electrical devices such as flashlights, smartphones, and electric cars. When a battery is supplying power, its positive terminal is the cathode. The terminal marked negative is the source of electrons that when connected to a circuit will flow. It is the movement of ions within the battery which allows current to flow out of the battery to perform work. Historically the term specifically referred to a device composed of multiple cells. Primary batteries are used once and discarded, the materials are irreversibly changed during discharge. Common examples are the battery used for flashlights and a multitude of portable electronic devices. Secondary batteries can be discharged and recharged multiple times using mains power from a wall socket, examples include the lead-acid batteries used in vehicles and lithium-ion batteries used for portable electronics such as laptops and smartphones. According to a 2005 estimate, the battery industry generates US$48 billion in sales each year. Batteries have much lower energy than common fuels such as gasoline. This is somewhat offset by the efficiency of electric motors in producing mechanical work. The usage of battery to describe a group of electrical devices dates to Benjamin Franklin, alessandro Volta built and described the first electrochemical battery, the voltaic pile, in 1800. This was a stack of copper and zinc plates, separated by brine-soaked paper disks, Volta did not understand that the voltage was due to chemical reactions. Although early batteries were of value for experimental purposes, in practice their voltages fluctuated. It consisted of a pot filled with a copper sulfate solution, in which was immersed an unglazed earthenware container filled with sulfuric acid. These wet cells used liquid electrolytes, which were prone to leakage and spillage if not handled correctly, many used glass jars to hold their components, which made them fragile and potentially dangerous. These characteristics made wet cells unsuitable for portable appliances, near the end of the nineteenth century, the invention of dry cell batteries, which replaced the liquid electrolyte with a paste, made portable electrical devices practical. Batteries convert chemical energy directly to electrical energy, a battery consists of some number of voltaic cells
6.
Alessandro Volta
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He invented the Voltaic pile in 1799, and reported the results of his experiments in 1800 in a two-part letter to the President of the Royal Society. With this invention Volta proved that electricity could be generated chemically, Voltas invention sparked a great amount of scientific excitement and led others to conduct similar experiments which eventually led to the development of the field of electrochemistry. Alessandro Volta also drew admiration from Napoleon Bonaparte for his invention, Volta enjoyed a certain amount of closeness with the Emperor throughout his life and he was conferred numerous honours by him. Alessandro Volta held the chair of physics at the University of Pavia for nearly 40 years and was widely idolised by his students. Despite his professional success, Volta tended to be a person inclined towards domestic life, at this time he tended to live secluded from public life and more for the sake of his family until his eventual death in 1827 from a series of illnesses which began in 1823. The SI unit of electric potential is named in his honour as the volt, Volta was born in Como, a town in present-day northern Italy, on 18 February 1745. In 1794, Volta married a lady also from Como, Teresa Peregrini. His father, Filippo Volta, was of noble lineage and his mother, Donna Maddalena, came from the family of the Inzaghis. In 1774, he became a professor of physics at the Royal School in Como, a year later, he improved and popularised the electrophorus, a device that produced static electricity. In 1777, he travelled through Switzerland, there he befriended H. B. de Saussure. In the years between 1776 and 1778, Volta studied the chemistry of gases and he researched and discovered methane after reading a paper by Benjamin Franklin of the United States on flammable air. In November 1776, he found methane at Lake Maggiore, and he devised experiments such as the ignition of methane by an electric spark in a closed vessel. Volta also studied what we now call electrical capacitance, developing separate means to both electrical potential and charge, and discovering that for a given object, they are proportional. This is called Voltas Law of Capacitance, and it was for work the unit of electrical potential has been named the volt. In 1779 he became a professor of physics at the University of Pavia. Luigi Galvani, an Italian physicist, discovered something he named animal electricity when two different metals were connected in series with a leg and to one another. Volta realised that the frogs leg served as both a conductor of electricity and as a detector of electricity and he replaced the frogs leg with brine-soaked paper, and detected the flow of electricity by other means familiar to him from his previous studies. This may be called Voltas Law of the electrochemical series, Volta had determined that the most effective pair of dissimilar metals to produce electricity was zinc and copper
7.
Electrolysis of water
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Electrolysis of water is the decomposition of water into oxygen and hydrogen gas due to an electric current being passed through the water. The reaction has a potential of −1.23 V. This technique can be used to make fuel and breathable oxygen. Jan Rudolph Deiman and Adriaan Paets van Troostwijk used, in 1789, in 1800 Alessandro Volta invented the voltaic pile, and a few weeks later William Nicholson and Anthony Carlisle used it for the electrolysis of water. When Zénobe Gramme invented the Gramme machine in 1869 electrolysis of water became a method for the production of hydrogen. A method of synthesis of hydrogen and oxygen through electrolysis was developed by Dmitry Lachinov in 1888. A DC electrical power source is connected to two electrodes, or two plates which are placed in the water, hydrogen will appear at the cathode, and oxygen will appear at the anode. Assuming ideal faradaic efficiency, the amount of hydrogen generated is twice the amount of oxygen, however, in many cells competing side reactions occur, resulting in different products and less than ideal faradaic efficiency. Electrolysis of pure water requires excess energy in the form of overpotential to overcome various activation barriers, without the excess energy the electrolysis of pure water occurs very slowly or not at all. This is in due to the limited self-ionization of water. Pure water has an electrical conductivity about one millionth that of seawater, many electrolytic cells may also lack the requisite electrocatalysts. The efficiency of electrolysis is increased through the addition of an electrolyte, currently the electrolytic process is rarely used in industrial applications since hydrogen can currently be produced more affordably from fossil fuels. In pure water at the negatively charged cathode, a reaction takes place. Not all half reactions must be balanced with acid or base, many do, like the oxidation or reduction of water listed here. To add half reactions they must both be balanced with acid or base. Assuming equal temperature and pressure for both gases, the hydrogen gas has therefore twice the volume of the produced oxygen gas. The number of electrons pushed through the water is twice the number of generated hydrogen molecules, decomposition of pure water into hydrogen and oxygen at standard temperature and pressure is not favorable in thermodynamic terms. Thus, the potential of the water electrolysis cell is −1.23 V at 25 °C at pH0
8.
William Nicholson (chemist)
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William Nicholson was a renowned English chemist and writer on natural philosophy and chemistry, as well as a translator, journalist, publisher, scientist, inventor, patent agent and civil engineer. Nicholson was educated in Yorkshire, and after leaving school, he made two voyages as a midshipman in the service of the British East India Company and his first ship was reportedly called The Boston and the second voyage was on board The Gatton. Subsequently, having become acquainted with Josiah Wedgwood in 1775, he moved to Amsterdam, meanwhile, he devoted himself to the preparation of An Introduction to Natural Philosophy, which was published in 1781 and was at once successful. A translation of Voltaires Elements of the Newtonian Philosophy soon followed and he gave much attention to the construction of various machines for comb-cutting, file-making, cylinder printing and other uses—he also invented an areometer. On 12 December 1783, Nicholson was elected to the Chapter Coffee House Philosophical Society and he was proposed by Jean-Hyacinthe Magellan and seconded by horologist John Whitehurst. Nicholson communicated to the Royal Society in 1789 two papers on electrical subjects, the journal included the first comprehensive descriptions of aerodynamics with George Cayleys On Aerial Navigation, which inspired the Wright brothers a hundred years later. In 1799 he established a school in Londons Soho Square, where he taught philosophy and chemistry. In May 1800 he with Anthony Carlisle discovered electrolysis, the decomposition of water into hydrogen and oxygen by voltaic current, the two were then appointed to a chemical investigation committee of the new Royal Institution. But his own interests shortly turned elsewhere, during the later years of his life, Nicholsons attention was chiefly directed to water supply engineering at Portsmouth, at Gosport and in Hammersmith. William Nicholson died in Bloomsbury at the age of 61 on 21 May 1815, attribution This article incorporates text from a publication now in the public domain, Nicholson, William
9.
Anthony Carlisle
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Sir Anthony Carlisle FRCS, FRS was an English surgeon. He was born in Stillington, County Durham, the son of Thomas Carlisle and his first wife. He w apprenticed to medical practitioners in York and Durham, including his uncle Anthony Hubback and he later studied in London under John Hunter. In 1793 he was appointed Surgeon at Westminster Hospital in 1793 and he was elected a Fellow of the Royal Society in 1804. He was Professor of Anatomy of the Society from 1808 to 1824, in 1815, he was appointed to the Council of the College of Surgeons and for many years was a curator of their Hunterian Museum. He served as president of the society, by then the Royal College of Surgeons and he twice delivered their Hunterian oration, causing consternation at his second oration in 1826 by using the occasion to talk about oysters, earning the epithet of Sir Anthony Oyster. He also delivered their Croonian Lecture in 1804,1805 and 1807 and he was Surgeon Extraordinary to King George IV, by whom he was knighted on 24 July 1821. It is possible that he may have been the author of The Horrors of Oakendale Abbey, the name Carver may be a reference to Carlisles profession. The name Carlisle is even mentioned in the book itself and he had married Martha Symmons, daughter of John Symmons, in Alcester, Warwickshire on 23 August 1800. On his death in 1840 he was buried in Kensal Green Cemetery, voltaic pile Timeline of hydrogen technologies Attribution This article incorporates text from a publication now in the public domain, Bettany, George Thomas. Works written by or about Anthony Carlisle at Wikisource Anthony Carlisles An essay on the disorders of old age, and on the means for prolonging human life
10.
Sodium
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Sodium is a chemical element with symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal, Sodium is an alkali metal, being in group 1 of the periodic table, because it has a single electron in its outer shell that it readily donates, creating a positively charged atom—the Na+ cation. Its only stable isotope is 23Na, the free metal does not occur in nature, but must be prepared from compounds. Sodium is the sixth most abundant element in the Earths crust, Sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. Among many other useful compounds, sodium hydroxide is used in soap manufacture, and sodium chloride is a de-icing agent. Sodium is an element for all animals and some plants. Sodium ions are the major cation in the fluid and as such are the major contributor to the ECF osmotic pressure. Loss of water from the ECF compartment increases the sodium concentration, isotonic loss of water and sodium from the ECF compartment decreases the size of that compartment in a condition called ECF hypovolemia. In nerve cells, the charge across the cell membrane enables transmission of the nerve impulse—an action potential—when the charge is dissipated. The melting and boiling points of sodium are lower than those of lithium but higher than those of the alkali metals potassium, rubidium. All of these high-pressure allotropes are insulators and electrides.3 nm, spin-orbit interactions involving the electron in the 3p orbital split the D line into two, at 589.0 and 589.6 nm, hyperfine structures involving both orbitals cause many more lines. Twenty isotopes of sodium are known, but only 23Na is stable, 23Na is created in the carbon-burning process in stars by fusing two carbon atoms together, this requires temperatures above 600 megakelvins and a star of at least three solar masses. Two nuclear isomers have been discovered, the one being 24mNa with a half-life of around 20.2 milliseconds. Sodium atoms have 11 electrons, one more than the stable configuration of the noble gas neon. This process requires so little energy that sodium is oxidized by giving up its 11th electron. In contrast, the ionization energy is very high, because the 10th electron is closer to the nucleus than the 11th electron. As a result, sodium usually forms ionic compounds involving the Na+ cation, the most common oxidation state for sodium is +1. It is generally less reactive than potassium and more reactive than lithium, Sodium metal is highly reducing, with the reduction of sodium ions requiring −2.71 volts, though potassium and lithium have even more negative potentials
11.
Potassium
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Potassium is a chemical element with symbol K and atomic number 19. It was first isolated from potash, the ashes of plants, in the periodic table, potassium is one of the alkali metals. Potassium in nature only in ionic salts. It is found dissolved in sea water, and is part of many minerals, naturally occurring potassium is composed of three isotopes, of which 40K is radioactive. Traces of 40K are found in all potassium, and it is the most common radioisotope in the human body, Potassium is chemically very similar to sodium, the previous element in Group 1 of the periodic table. They have a similar energy, which allows for each atom to give up its sole outer electron. That they are different elements combine with the same anions to make similar salts was suspected in 1702. Most industrial applications of potassium exploit the high solubility in water of potassium compounds, heavy crop production rapidly depletes the soil of potassium, and this can be remedied with agricultural fertilizers containing potassium, accounting for 95% of global potassium chemical production. Potassium ions are necessary for the function of all living cells, fresh fruits and vegetables are good dietary sources of potassium. Potassium is the second least dense metal after lithium and it is a soft solid with a low melting point, and can be easily cut with a knife. Freshly cut potassium is silvery in appearance, but it begins to tarnish toward gray immediately on exposure to air, in a flame test, potassium and its compounds emit a lilac color with a peak emission wavelength of 766.5 nanometers. Neutral potassium atoms have 19 electrons, one more than the stable configuration of the noble gas argon. This process requires so little energy that potassium is readily oxidized by atmospheric oxygen, in contrast, the second ionization energy is very high, because removal of two electrons breaks the stable noble gas electronic configuration. Potassium therefore does not readily form compounds with the state of +2 or higher. Potassium is an active metal that reacts violently with oxygen in water. With oxygen it forms potassium peroxide, and with water potassium forms potassium hydroxide, the reaction of potassium with water is dangerous because of its violent exothermic character and the production of hydrogen gas. Hydrogen reacts again with atmospheric oxygen, producing water, which reacts with the remaining potassium and this reaction requires only traces of water, because of this, potassium and the liquid sodium-potassium — NaK — are potent desiccants that can be used to dry solvents prior to distillation. Because of the sensitivity of potassium to water and air, reactions with other elements are only in an inert atmosphere such as argon gas using air-free techniques
12.
Calcium
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Calcium is a chemical element with symbol Ca and atomic number 20. Calcium is a soft grayish-yellow alkaline earth metal, fifth-most-abundant element by mass in the Earths crust, the ion Ca2+ is also the fifth-most-abundant dissolved ion in seawater by both molarity and mass, after sodium, chloride, magnesium, and sulfate. Free calcium metal is too reactive to occur in nature, Calcium is produced in supernova nucleosynthesis. Calcium is a trace element in living organisms. It is the most abundant metal by mass in animals, and it is an important constituent of bone, teeth. In cell biology, the movement of the calcium ion into, Calcium carbonate and calcium citrate are often taken as dietary supplements. Calcium is on the World Health Organizations List of Essential Medicines, Calcium has a wide variety of applications, almost all of which are associated with calcium compounds and salts. Calcium metal is used as a deoxidizer, desulfurizer, and decarbonizer for production of ferrous and nonferrous alloys. In steelmaking and production of iron, Ca reacts with oxygen, Calcium carbonate is used in manufacturing cement and mortar, lime, limestone and aids in production in the glass industry. It also has chemical and optical uses as mineral specimens in toothpastes, Calcium hydroxide solution is used to detect the presence of carbon dioxide in a gas sample bubbled through a solution. The solution turns cloudy where CO2 is present, Calcium arsenate is used in insecticides. Calcium carbide is used to make acetylene gas and various plastics, Calcium chloride is used in ice removal and dust control on dirt roads, as a conditioner for concrete, as an additive in canned tomatoes, and to provide body for automobile tires. Calcium citrate is used as a food preservative, Calcium cyclamate is used as a sweetening agent in several countries. In the United States, it has been outlawed as a suspected carcinogen, Calcium gluconate is used as a food additive and in vitamin pills. Calcium hypochlorite is used as a swimming pool disinfectant, as an agent, as an ingredient in deodorant. Calcium permanganate is used in rocket propellant, textile production, as a water sterilizing agent. Calcium phosphate is used as a supplement for animal feed, fertilizer, in production for dough and yeast products, in the manufacture of glass. Calcium phosphide is used in fireworks, rodenticide, torpedoes, Calcium sulfate is used as common blackboard chalk, as well as, in its hemihydrate form, Plaster of Paris
13.
Boron
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Boron is a chemical element with symbol B and atomic number 5. Produced entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, it is an element in the Solar system. Boron is concentrated on Earth by the water-solubility of its more common naturally occurring compounds and these are mined industrially as evaporites, such as borax and kernite. The largest known deposits are in Turkey, the largest producer of boron minerals. Elemental boron is a metalloid that is found in small amounts in meteoroids, industrially, very pure boron is produced with difficulty because of refractory contamination by carbon or other elements. Several allotropes of boron exist, amorphous boron is a powder, crystalline boron is silvery to black, extremely hard. The primary use of boron is as boron filaments with applications similar to carbon fibers in some high-strength materials. Boron is primarily used in chemical compounds, about half of all consumption globally, boron is used as an additive in glass fibers of boron-containing fiberglass for insulation and structural materials. The next leading use is in polymers and ceramics in high-strength, lightweight structural, borosilicate glass is desired for its greater strength and thermal shock resistance than ordinary soda lime glass. Boron compounds are used as fertilizers in agriculture and in sodium perborate bleaches, a small amount of boron is used as a dopant in semiconductors, and reagent intermediates in the synthesis of organic fine chemicals. A few boron-containing organic pharmaceuticals are used or are in study, natural boron is composed of two stable isotopes, one of which has a number of uses as a neutron-capturing agent. In biology, borates have low toxicity in mammals, but are toxic to arthropods and are used as insecticides. Boric acid is mildly antimicrobial, and several natural boron-containing organic antibiotics are known, small amounts of boron compounds play a strengthening role in the cell walls of all plants, making boron a necessary plant nutrient. Boron is involved in the metabolism of calcium in both plants and animals and it is considered an essential nutrient for humans, and boron deficiency is implicated in osteoporosis. The word boron was coined from borax, the mineral from which it was isolated, by analogy with carbon, marco Polo brought some glazes back to Italy in the 13th century. Agricola, around 1600, reports the use of borax as a flux in metallurgy, in 1777, boric acid was recognized in the hot springs near Florence, Italy, and became known as sal sedativum, with primarily medical uses. The rare mineral is called sassolite, which is found at Sasso, Sasso was the main source of European borax from 1827 to 1872, when American sources replaced it. Boron compounds were relatively rarely used until the late 1800s when Francis Marion Smiths Pacific Coast Borax Company first popularized and produced them in volume at low cost
14.
Barium
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Barium is a chemical element with symbol Ba and atomic number 56. It is the element in Group 2, a soft silvery metallic alkaline earth metal. Because of its chemical reactivity, barium is never found in nature as a free element. Its hydroxide, known in history as baryta, does not occur as a mineral. The most common naturally occurring minerals of barium are barite and witherite, the barium name originates from the alchemical derivative baryta, from Greek βαρύς, meaning heavy. Baric is the form of barium. Barium was identified as a new element in 1774, but not reduced to a metal until 1808 with the advent of electrolysis, historically, it was used as a getter for vacuum tubes. It is a component of YBCO and electroceramics, and is added to steel, Barium compounds are added to fireworks to impart a green color. Barium sulfate is used as an additive to oil well drilling fluid, as well as in a purer form. The soluble barium ion and soluble compounds are poisonous, and have used as rodenticides. Barium is a soft, silvery-white metal, with a slight golden shade when ultrapure, the silvery-white color of barium metal rapidly vanishes upon oxidation in air yielding a dark gray oxide layer. Barium has a specific weight and good electrical conductivity. Ultrapure barium is very difficult to prepare, and therefore properties of barium have not been accurately measured yet. At room temperature and pressure, barium has a cubic structure, with a barium–barium distance of 503 picometers. It is a soft metal with a Mohs hardness of 1.25. Its melting temperature of 1,000 K is intermediate between those of the strontium and heavier radium, however, its boiling point of 2,170 K exceeds that of strontium. The density is again intermediate between those of strontium and radium, Barium is chemically similar to magnesium, calcium, and strontium, but even more reactive. It always exhibits the oxidation state of +2, except in a few rare, reactions with chalcogens are highly exothermic, the reaction with oxygen or air occurs at room temperature, and therefore barium is stored under oil or in an inert atmosphere
15.
Strontium
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Strontium is a chemical element with symbol Sr and atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically, the metal forms a dark oxide layer when it is exposed to air. Strontium has physical and chemical properties similar to those of its two neighbors in the periodic table, calcium and barium. It occurs naturally in the minerals celestine, strontianite, and putnisite, natural stable strontium, on the other hand, is not hazardous to health. Strontium was first isolated as a metal in 1808 by Humphry Davy using the then-newly discovered process of electrolysis, the production of sugar from sugar beet was in the 19th century the largest application of strontium. At the peak of production of cathode ray tubes, as much as 75 percent of strontium consumption in the United States was used for the faceplate glass. With the displacement of cathode ray tubes by other display methods, Strontium is a divalent silvery metal with a pale yellow tint whose properties are mostly intermediate between and similar to those of its group neighbors calcium and barium. It is softer than calcium and harder than barium and its melting and boiling points are lower than those of calcium, barium continues this downward trend in the melting point, but not in the boiling point. The density of strontium is similarly intermediate between those of calcium and barium, three allotropes of metallic strontium exist, with transition points at 235 and 540 °C. The standard electrode potential for the Sr2+/Sr couple is −2.89 V, Strontium is intermediate between calcium and barium in its reactivity toward water, with which it reacts on contact to produce strontium hydroxide and hydrogen gas. Strontium metal burns in air to produce both strontium oxide and strontium nitride, but since it does not react with nitrogen below 380 °C, at room temperature, it forms only the oxide spontaneously. Besides the simple oxide SrO, the peroxide SrO2 can be made by oxidation of strontium metal under a high pressure of oxygen. Strontium hydroxide, Sr2, is a base, though it is not as strong as the hydroxides of barium or the alkali metals. Due to the size of the heavy s-block elements, including strontium. Organostrontium compounds contain one or more strontium–carbon bonds and they have been reported as intermediates in Barbier-type reactions. Organostrontium compounds tend to be similar to organoeuropium or organosamarium compounds due to the similar ionic radii of these elements. Most of these compounds can only be prepared at low temperatures, because of its extreme reactivity with oxygen and water, this element occurs naturally only in compounds with other elements, such as in the minerals strontianite and celestine. It is kept under a liquid such as mineral oil or kerosene to prevent oxidation
16.
Magnesium
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Magnesium is a chemical element with symbol Mg and atomic number 12. Magnesium is the ninth most abundant element in the universe and it is produced in large, aging stars from the sequential addition of three helium nuclei to a carbon nucleus. When such stars explode as supernovas, much of the magnesium is expelled into the medium where it may recycle into new star systems. Magnesium is the eighth most abundant element in the Earths crust and the fourth most common element in the Earth, making up 13% of the planets mass and it is the third most abundant element dissolved in seawater, after sodium and chlorine. Magnesium occurs naturally only in combination with elements, where it invariably has a +2 oxidation state. The free element can be produced artificially, and is highly reactive, the free metal burns with a characteristic brilliant-white light. The metal is now obtained mainly by electrolysis of magnesium salts obtained from brine, Magnesium is less dense than aluminium, and the alloy is prized for its combination of lightness and strength. Magnesium is the eleventh most abundant element by mass in the body and is essential to all cells. Magnesium ions interact with polyphosphate compounds such as ATP, DNA, hundreds of enzymes require magnesium ions to function. Magnesium compounds are used medicinally as common laxatives, antacids, elemental magnesium is a gray-white lightweight metal, two-thirds the density of aluminium. Magnesium has the lowest melting and the lowest boiling point 1,363 K of all the alkaline earth metals, Magnesium reacts with water at room temperature, though it reacts much more slowly than calcium, a similar group 2 metal. When submerged in water, hydrogen bubbles form slowly on the surface of the metal—though, if powdered, the reaction occurs faster with higher temperatures. Magnesiums reversible reaction with water can be harnessed to store energy, Magnesium also reacts exothermically with most acids such as hydrochloric acid, producing the metal chloride and hydrogen gas, similar to the HCl reaction with aluminium, zinc, and many other metals. Magnesium is highly flammable, especially when powdered or shaved into thin strips, flame temperatures of magnesium and magnesium alloys can reach 3,100 °C, although flame height above the burning metal is usually less than 300 mm. Once ignited, such fires are difficult to extinguish, with combustion continuing in nitrogen, carbon dioxide, Magnesium may also be used as an igniter for thermite, a mixture of aluminium and iron oxide powder that ignites only at a very high temperature. When burning in air, magnesium produces a light that includes strong ultraviolet wavelengths. Magnesium powder was used for illumination in the early days of photography. Later, magnesium filament was used in electrically ignited single-use photography flashbulbs, Magnesium powder is used in fireworks and marine flares where a brilliant white light is required
17.
Humphry Davy
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He also studied the forces involved in these separations, inventing the new field of electrochemistry. Berzelius called Davys 1806 Bakerian Lecture On Some Chemical Agencies of Electricity one of the best memoirs which has ever enriched the theory of chemistry and he was a Baronet, President of the Royal Society, Member of the Royal Irish Academy, and Fellow of the Geological Society. He also invented the Davy Lamp and an early form of incandescent light bulb. Davy was born in Penzance in Cornwall in England on 17 December 1778 and his family moved to Varfell, near Ludgvan, when he was nine, and in term-time Davy boarded with John Tonkin, his mothers godfather. Davy said, I consider it fortunate I was left much to myself as a child, after Davys father died in 1794, Tonkin apprenticed him to John Bingham Borlase, a surgeon with a practice in Penzance. Davys indenture is dated 10 February 1795, in the apothecarys dispensary, Davy became a chemist, and a garret in Tonkins house was where he conducted his earliest chemical experiments. Davys friends said, This boy Humphry is incorrigible and he will blow us all into the air. His elder sister complained of the ravages made on her dresses by corrosive substances, John Ayrton Paris remarked that poetry written by the young Davy bear the stamp of lofty genius. Davys first preserved poem entitled The Sons of Genius is dated 1795, other poems written in the following years, especially On the Mounts Bay and St Michaels Mount, are descriptive verses, showing sensibility but no true poetic imagination. Three of Davys paintings from around 1796 have been donated to the Penlee House museum at Penzance, one is of the view from above Gulval showing the church, Mounts Bay and the Mount, while the other two depict Loch Lomond in Scotland. While writing verses at the age of 17 in honour of his first love, he was discussing the question of the materiality of heat with his Quaker friend. Dunkin remarked, I tell thee what, Humphry, thou art the most quibbling hand at a dispute I ever met with in my life and it was a crude form of analogous experiment exhibited by Davy in the lecture-room of the Royal Institution that elicited considerable attention. As professor at the Royal Institution, Davy repeated many of the experiments he learned from his friend and mentor. Davies Giddy met Davy in Penzance carelessly swinging on the half-gate of Dr Borlases house and this led to an introduction to Dr Edwards, who lived at Hayle Copper House. Edwards was a lecturer in chemistry in the school of St. Bartholomews Hospital, galvanic corrosion was not understood at that time, but the phenomenon prepared Davys mind for subsequent experiments on ships copper sheathing. Gregory Watt, son of James Watt, visited Penzance for his healths sake, Davy was acquainted with the Wedgwood family, who spent a winter at Penzance. Thomas Beddoes and John Hailstone were engaged in a controversy on the rival merits of the Plutonian. They travelled together to examine the Cornish coast accompanied by Davies Gilbert, Beddoes, who had established at Bristol a Pneumatic Institution, needed an assistant to superintend the laboratory
18.
Daniell cell
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He was searching for a way to eliminate the hydrogen bubble problem found in the voltaic pile, and his solution was to use a second electrolyte to consume the hydrogen produced by the first. Zinc sulfate may be substituted for the sulfuric acid, the Daniell cell was a great improvement over the existing technology used in the early days of battery development. A later variant of the Daniell cell called the gravity cell or crowfoot cell was invented in the 1860s by a Frenchman named Callaud and became a popular choice for electrical telegraphy. The Daniell cell is also the basis for the contemporary definition of the volt. The definitions of units that were proposed at the 1881 International Conference of Electricians were designed so that the electromotive force of the Daniell cell would be about 1.0 volts. With contemporary definitions, the potential of the Daniell cell at 25 °C is actually 1.10 V. In the Daniell cell, copper and zinc electrodes are immersed in a solution of copper sulfate, at the anode, zinc is oxidized per the following half reaction, Zn → Zn2+ + 2e−. At the cathode, copper is reduced per the following reaction, the total reaction being, Zn + Cu2+ → Zn2+ + Cu. In classroom demonstrations, a form of the Daniell cell known as two cells is often used due to its simplicity. The two half cells each support one half of the described above. A wire and light bulb may connect the two electrodes, electrons that are “pulled” from the zinc anode travel through the wire, providing an electrical current that illuminates the bulb. In such a cell, the play an important role. Having a negative charge, the build up around the anode to maintain a neutral charge. Conversely, at the cathode the copper cations discharge to maintain a neutral charge and these two processes accompany the accumulation of copper solid at the cathode and the corrosion of the zinc electrode into the solution as zinc cations. Since neither half reaction will occur independently of the other, the two cells must be connected in a way that will allow ions to move freely between them. A porous barrier or ceramic disk may be used to separate the two solutions while allowing the flow of sulfate ions, when the half cells are placed in two entirely different and separate containers, a salt bridge is often used to connect the two cells. The salt bridge typically contains a concentration of potassium nitrate. In the above wet-cell during discharge, nitrate anions in the salt bridge move into the zinc half-cell in order to balance the increase in Zn2+ ions
19.
Grove cell
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The Grove cell voltage is about 1. The Grove cell was limited in respect, because as the cell discharged. Eventually, Grove cells were replaced in use by Daniell cells, history of the battery Bunsen cell, Using cheaper carbon instead of platinum
20.
Dynamo
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A dynamo is an electrical generator that produces direct current with the use of a commutator. Today, the simpler alternator dominates large scale power generation, for efficiency, reliability, a dynamo has the disadvantages of a mechanical commutator. Also, converting alternating to direct current using power rectification devices is effective, the word dynamo was originally another name for an electrical generator, and still has some regional usage as a replacement for the word generator. The word dynamo was coined by Werner von Siemens in 1882, the original dynamo principle of W. Siemens meant only the direct current generators which use exclusively the self-excitation principle to generate DC power. The earlier DC generators which used permanent magnets were not considered dynamo electric machines, the invention of the Dynamo principle was a huge technological leap over the old traditional permanent magnet based DC generators. The discovery of the dynamo principle made the industrial scale electric power generation technically and economically feasible, a small electrical generator built into the hub of a bicycle wheel to power lights is called a hub dynamo, although these are invariably AC devices, and are actually magnetos. The electric dynamo uses rotating coils of wire and magnetic fields to convert mechanical rotation into a direct electric current through Faradays law of induction. A dynamo machine consists of a structure, called the stator, which provides a constant magnetic field. Due to Faradays law of induction the motion of the wire within the field creates an electromotive force which pushes on the electrons in the metal. The commutator is needed to direct current. When a loop of wire rotates in a field, the magnetic flux through it. However, in the days of electric experimentation, alternating current generally had no known use. The few uses for electricity, such as electroplating, used direct current provided by messy liquid batteries, dynamos were invented as a replacement for batteries. The commutator is essentially a rotary switch and it consists of a set of contacts mounted on the machines shaft, combined with graphite-block stationary contacts, called brushes, because the earliest such fixed contacts were metal brushes. The commutator reverses the connection of the windings to the circuit when the potential reverses, so instead of alternating current. The earliest dynamos used permanent magnets to create the magnetic field and these were referred to as magneto-electric machines or magnetos. However, researchers found that magnetic fields, and so more power. These were called dynamo-electric machines or dynamos, the field coils of the stator were originally separately excited by a separate, smaller, dynamo or magneto
21.
Luigi Galvani
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Luigi Aloisio Galvani was an Italian physician, physicist, biologist and philosopher, who discovered animal electricity. He is recognized as the pioneer of bioelectromagnetics, in 1780, he discovered that the muscles of dead frogs legs twitched when struck by an electrical spark. This was one of the first forays into the study of bioelectricity, Luigi Galvani was born to Domenico and Barbara Foschi, in Bologna, Papal State. Domenico was a goldsmith and Barbara was his fourth wife and his family was not aristocratic, but they could afford to send at least one of their sons to study at a university. At first Galvani wished to enter the church, so he joined a religious institution, Oratorio dei Padri Filippini, at 15 years old. He planned to take vows, but his parents persuaded him not to do so. Around 1755, Galvani entered the Faculty of the Arts of the University of Bologna, Galvani attended the medicine course, which lasted four years, and was characterized by its bookish teaching. Texts that dominated this course were by Hippocrates, Galen, another discipline Galvani learned alongside medicine was surgery. He learned the theory and the practice and this part of his biography is typically overlooked, but it helped with his experiments with animals and helped familiarize Galvani with the manipulation of a living body. In 1759, Galvani graduated with degrees in medicine and philosophy and he applied for a position as a lecturer at the university. Part of this required him to defend his thesis on 21 June 1761. In the following year,1762, he became a permanent anatomist of the university and was appointed lecturer of surgery. That same year he married Lucia Galeazzi, daughter of one of his professors, Galvani moved into the Galeazzi house and helped with his father-in-laws research. When Galeazzi died in 1775, Galvani was appointed professor and lecturer in Galeazzis place, Galvani moved from the position of lecturer of surgery to theoretical anatomy and obtained an appointment at the Academy of Sciences in 1776. His new appointment consisted of the teaching of anatomy, which was conducted by human dissection. As a Benedectine member of the Academy of Sciences, Galvani had specific responsibilities and his main responsibility was to present at least one research paper every year at the Academy, which Galvani did until his death. There was a publication that collected a selection of the memoirs presented at the institution and was sent around to main scientific academies. However, since then was so slow, sometimes there were debates on priority of the topics used
22.
Brine
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Brine is a solution of salt in water. In different contexts, brine may refer to salt solutions ranging from about 3. 5% up to about 26%, fahrenheit could reliably reproduce by freezing brine. By reference, seawater usually freezes at −2 °C, at 100 °C, saturated sodium chloride brine is about 28% salt by weight. At 0 °C, brine can only hold about 26% salt, the thermal conductivity of seawater is 0.6 W/mK at 25 °C. The majority of hydrogen produced through electrolysis is a side product in the production of chlorine. 2 NaCl +2 H2O →2 NaOH + H2 + Cl2 Brine is a fluid used in large refrigeration installations for the transport of thermal energy from place to place. The lowest freezing point obtainable for NaCl brine is −21.1 °C at 23. 3wt% NaCl and this is called the eutectic point. In lower temperatures, a solution can be used to de-ice or reduce freezing temperatures on roads. In cooking, brine is used for food brining and salting, in hydrology, brine is a form of salt water, namely, water with relatively high concentration of salt. Brine mining Saline water Brackish water
23.
Electricity
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Electricity is the set of physical phenomena associated with the presence of electric charge. Although initially considered a separate to magnetism, since the development of Maxwells Equations both are recognized as part of a single phenomenon, electromagnetism. Various common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges, in addition, electricity is at the heart of many modern technologies. The presence of a charge, which can be either positive or negative. On the other hand, the movement of charges, which is known as electric current. When a charge is placed in a location with non-zero electric field, the magnitude of this force is given by Coulombs Law. Thus, if that charge were to move, the field would be doing work on the electric charge. Electrical phenomena have been studied since antiquity, though progress in theoretical understanding remained slow until the seventeenth and eighteenth centuries. Even then, practical applications for electricity were few, and it would not be until the nineteenth century that engineers were able to put it to industrial and residential use. The rapid expansion in electrical technology at this time transformed industry, electricitys extraordinary versatility means it can be put to an almost limitless set of applications which include transport, heating, lighting, communications, and computation. Electrical power is now the backbone of modern industrial society, long before any knowledge of electricity existed, people were aware of shocks from electric fish. Ancient Egyptian texts dating from 2750 BCE referred to these fish as the Thunderer of the Nile, Electric fish were again reported millennia later by ancient Greek, Roman and Arabic naturalists and physicians. Patients suffering from such as gout or headache were directed to touch electric fish in the hope that the powerful jolt might cure them. Ancient cultures around the Mediterranean knew that certain objects, such as rods of amber, Thales was incorrect in believing the attraction was due to a magnetic effect, but later science would prove a link between magnetism and electricity. He coined the New Latin word electricus to refer to the property of attracting small objects after being rubbed and this association gave rise to the English words electric and electricity, which made their first appearance in print in Thomas Brownes Pseudodoxia Epidemica of 1646. Further work was conducted by Otto von Guericke, Robert Boyle, Stephen Gray, in the 18th century, Benjamin Franklin conducted extensive research in electricity, selling his possessions to fund his work. In June 1752 he is reputed to have attached a key to the bottom of a dampened kite string. A succession of jumping from the key to the back of his hand showed that lightning was indeed electrical in nature
24.
Silver
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Silver is a metallic element with symbol Ag and atomic number 47. The symbol Ag stems from Latin argentum, derived from the Greek ὰργὀς, a soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. The metal is found in the Earths crust in the pure, free form, as an alloy with gold and other metals. Most silver is produced as a byproduct of copper, gold, lead, Silver is more abundant than gold, but it is much less abundant as a native metal. Its purity is measured on a per mille basis, a 94%-pure alloy is described as 0.940 fine. As one of the seven metals of antiquity, silver has had a role in most human cultures. Silver has long valued as a precious metal. Silver metal is used in many premodern monetary systems in bullion coins, Silver is used in numerous applications other than currency, such as solar panels, water filtration, jewelry, ornaments, high-value tableware and utensils, and as an investment medium. Silver is used industrially in electrical contacts and conductors, in specialized mirrors, window coatings, Silver compounds are used in photographic film and X-rays. Dilute silver nitrate solutions and other compounds are used as disinfectants and microbiocides, added to bandages and wound-dressings, catheters. Silver is similar in its physical and chemical properties to its two neighbours in group 11 of the periodic table, copper and gold. This distinctive electron configuration, with an electron in the highest occupied s subshell over a filled d subshell. Silver is a soft, ductile and malleable transition metal. Silver crystallizes in a cubic lattice with bulk coordination number 12. Unlike metals with incomplete d-shells, metallic bonds in silver are lacking a covalent character and are relatively weak and this observation explains the low hardness and high ductility of single crystals of silver. Silver has a brilliant white metallic luster that can take a polish. Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than ~450 nm, at wavelengths shorter than 450 nm, silvers reflectivity is inferior to that of aluminium and drops to zero near 310 nm. The electrical conductivity of silver is the greatest of all metals, greater even than copper, during World War II in the US,13540 tons of silver were used in electromagnets for enriching uranium, mainly because of the wartime shortage of copper
25.
Electrode
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An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit. The word was coined by William Whewell at the request of the scientist Michael Faraday from the Greek words elektron, meaning amber, and hodos, an electrode in an electrochemical cell is referred to as either an anode or a cathode. The anode is now defined as the electrode at which electrons leave the cell and oxidation occurs, each electrode may become either the anode or the cathode depending on the direction of current through the cell. A bipolar electrode is an electrode that functions as the anode of one cell, a primary cell is a special type of electrochemical cell in which the reaction cannot be reversed, and the identities of the anode and cathode are therefore fixed. The anode is always the negative electrode, the cell can be discharged but not recharged. A secondary cell, for example a rechargeable battery, is a cell in which the reactions are reversible. When the cell is being charged, the anode becomes the positive and this is also the case in an electrolytic cell. When the cell is being discharged, it behaves like a cell, with the anode as the negative. In a vacuum tube or a semiconductor having polarity the anode is the positive electrode, the electrons enter the device through the cathode and exit the device through the anode. Many devices have other electrodes to control operation, e. g. base, gate, control grid. In a three-electrode cell, an electrode, also called an auxiliary electrode, is used only to make a connection to the electrolyte so that a current can be applied to the working electrode. The counter electrode is made of an inert material, such as a noble metal or graphite. In arc welding an electrode is used to conduct current through a workpiece to fuse two pieces together. Depending upon the process, the electrode is either consumable, in the case of gas metal arc welding or shielded metal arc welding, or non-consumable, such as in gas tungsten arc welding. For a direct current system the weld rod or stick may be a cathode for a filling type weld or an anode for other welding processes, for an alternating current arc welder the welding electrode would not be considered an anode or cathode. Electrodes are used to provide current through nonmetal objects to them in numerous ways. These electrodes are used for advanced purposes in research and investigation
26.
Electrolyte
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An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water. The dissolved electrolyte separates into cations and anions, which disperse uniformly through the solvent, electrically, such a solution is neutral. The movement of anions and cations in opposite directions within the solution amounts to a current and this includes most soluble salts, acids, and bases. Some gases, such as chloride, under conditions of high temperature or low pressure can also function as electrolytes. Electrolyte solutions can also result from the dissolution of some biological and synthetic polymers, termed polyelectrolytes, a substance that dissociates into ions in solution acquires the capacity to conduct electricity. Sodium, potassium, chloride, calcium, magnesium, and phosphate are examples of electrolytes, in medicine, electrolyte replacement is needed when a patient has prolonged vomiting or diarrhea, and as a response to strenuous athletic activity. Commercial electrolyte solutions are available, particularly for children and athletes. Electrolyte monitoring is important in the treatment of anorexia and bulimia, the word electrolyte derives from the Greek lytós, meaning able to be untied or loosened. Arrheniuss explanation was that in forming a solution, the salt dissociates into charged particles, faradays belief had been that ions were produced in the process of electrolysis. Arrhenius proposed that, even in the absence of an electric current and he thus proposed that chemical reactions in solution were reactions between ions. For example, carbon dioxide gas dissolves in water to produce a solution that contains hydronium, carbonate, molten salts can also be electrolytes as, for example, when sodium chloride is molten, the liquid conducts electricity. An electrolyte in a solution may be described as concentrated if it has a concentration of ions. If a high proportion of the solute dissociates to form ions, the electrolyte is strong, if most of the solute does not dissociate. The properties of electrolytes may be exploited using electrolysis to extract constituent elements, in physiology, the primary ions of electrolytes are sodium, potassium, calcium, magnesium, chloride, hydrogen phosphate, and hydrogen carbonate. The electric charge symbols of plus and minus indicate that the substance is ionic in nature and has a distribution of electrons. Sodium is the main electrolyte found in extracellular fluid and potassium is the main intracellular electrolyte, all known higher lifeforms require a subtle and complex electrolyte balance between the intracellular and extracellular environments. In particular, the maintenance of precise osmotic gradients of electrolytes is important, such gradients affect and regulate the hydration of the body as well as blood pH, and are critical for nerve and muscle function. Various mechanisms exist in living species that keep the concentrations of different electrolytes under tight control, both muscle tissue and neurons are considered electric tissues of the body
27.
Current (electricity)
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An electric current is a flow of electric charge. In electric circuits this charge is carried by moving electrons in a wire. It can also be carried by ions in an electrolyte, or by both ions and electrons such as in an ionised gas. The SI unit for measuring a current is the ampere. Electric current is measured using a device called an ammeter, electric currents cause Joule heating, which creates light in incandescent light bulbs. They also create magnetic fields, which are used in motors, inductors and generators, the particles that carry the charge in an electric current are called charge carriers. In metals, one or more electrons from each atom are loosely bound to the atom and these conduction electrons are the charge carriers in metal conductors. The conventional symbol for current is I, which originates from the French phrase intensité de courant, current intensity is often referred to simply as current. The I symbol was used by André-Marie Ampère, after whom the unit of current is named, in formulating the eponymous Ampères force law. The notation travelled from France to Great Britain, where it became standard, in a conductive material, the moving charged particles which constitute the electric current are called charge carriers. In other materials, notably the semiconductors, the carriers can be positive or negative. Positive and negative charge carriers may even be present at the same time, a flow of positive charges gives the same electric current, and has the same effect in a circuit, as an equal flow of negative charges in the opposite direction. Since current can be the flow of positive or negative charges. The direction of current is arbitrarily defined as the same direction as positive charges flow. This is called the direction of current I. If the current flows in the direction, the variable I has a negative value. When analyzing electrical circuits, the direction of current through a specific circuit element is usually unknown. Consequently, the directions of currents are often assigned arbitrarily
28.
History of the battery
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Batteries provided the main source of electricity before the development of electric generators and electrical grids around the end of the 19th century. Scientists and engineers developed several commercially important types of battery, wet cells were open containers that held liquid electrolyte and metallic electrodes. When the electrodes were consumed, the wet cell was renewed by replacing the electrodes. Open containers are unsuitable for mobile or portable use, early electric cars used semi-sealed wet cells. Primary batteries could produce current as soon as assembled, but once the active elements were consumed, the development of the lead-acid battery and subsequent secondary or rechargeable types allowed energy to be restored to the cell, extending the life of permanently assembled cells. In 1749 Benjamin Franklin, the U. S. polymath and founding father and these capacitors were panels of glass coated with metal on each surface. These capacitors were charged with a generator and discharged by touching metal to their electrode. Linking them together in a battery gave a stronger discharge, today even a single electrochemical cell, e. g. a dry cell, is commonly called a battery. In 1780, Luigi Galvani was dissecting a frog affixed to a brass hook, when he touched its leg with his iron scalpel, the leg twitched. Galvani believed the energy that drove this contraction came from the leg itself, however, Alessandro Volta, a friend and fellow scientist, disagreed, believing this phenomenon was caused by two different metals joined together by a moist intermediary. He verified this hypothesis through experiment, and published the results in 1791, in 1800, Volta invented the first true battery, which came to be known as the voltaic pile. The voltaic pile consisted of pairs of copper and zinc discs piled on top of each other and he experimented with various metals and found that zinc and silver gave the best results. Volta believed the current was the result of two different materials simply touching each other—an obsolete scientific theory known as contact tension—and not the result of chemical reactions. As a consequence, he regarded the corrosion of the plates as an unrelated flaw that could perhaps be fixed by changing the materials somehow. However, no scientist ever succeeded in preventing this corrosion, in fact, it was observed that the corrosion was faster when a higher current was drawn. This suggested that the corrosion was actually integral to the ability to produce a current. This, in part, led to the rejection of Voltas contact tension theory in favor of electrochemical theory, Voltas illustrations of his Crown of Cups and voltaic pile have extra metal disks, now known to be unnecessary, on both the top and bottom. The figure associated with this section, of the voltaic pile, has the modern design
29.
Joseph Banks
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Sir Joseph Banks, 1st Baronet, GCB, PRS was a British naturalist, botanist and patron of the natural sciences. Banks made his name on the 1766 natural history expedition to Newfoundland and he took part in Captain James Cooks first great voyage, visiting Brazil, Tahiti, and, after 6 months in New Zealand, Australia, returning to immediate fame. He held the position of President of the Royal Society for over 41 years and he advised King George III on the Royal Botanic Gardens, Kew, and by sending botanists around the world to collect plants, he made Kew the worlds leading botanical gardens. He is credited with introducing the eucalyptus, acacia, and the named after him, Banksia. Approximately 80 species of plants bear his name and he was the leading founder of the African Association and a member of the Society of Dilettanti which helped to establish the Royal Academy. Banks was born on Argyle Street in London to William Banks, a wealthy Lincolnshire country squire and member of the House of Commons and he had a younger sister, Sarah Sophia Banks, born in 1744. Banks was educated at Harrow School from the age of 9 and at Eton College from 1756, as a boy, Banks enjoyed exploring the Lincolnshire countryside and developed a keen interest in nature, history and botany. When he was 17, he was inoculated with smallpox, but he became ill, in late 1760, he was enrolled as a gentleman-commoner at the University of Oxford. At Oxford, he matriculated at Christ Church, where his studies were focused on natural history rather than the classical curriculum. Determined to receive instruction, he paid the Cambridge botanist Israel Lyons to deliver a series of lectures at Oxford in 1764. Banks left Oxford for Chelsea in December 1763 and he continued to attend the university until 1764, but left that year without taking a degree. He began to make friends among the men of his day and to correspond with Carl Linnaeus. As Bankss influence increased, he became an adviser to King George III and urged the monarch to support voyages of discovery to new lands and he became a Freemason sometime before 1769. He made his name by publishing the first Linnean descriptions of the plants and animals of Newfoundland and his diary, describing his expedition to Newfoundland, was rediscovered recently in the Royal Geographical Society of South Australia. Banks also documented 34 species of birds, including the great auk, on 7 May, he noted a large number of penguins swimming around the ship on the Grand Banks, and a specimen he collected in Chateau Bay, Labrador, was later identified as the great auk. Banks was appointed to a joint Royal Navy/Royal Society scientific expedition to the south Pacific Ocean on HMS Endeavour and this was the first of James Cooks voyages of discovery in that region. Banks funded seven others to him, the Swedish naturalist Daniel Solander. The voyage went to Brazil, where Banks made the first scientific description of a now common garden plant, bougainvillea, and to other parts of South America
30.
London
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London /ˈlʌndən/ is the capital and most populous city of England and the United Kingdom. Standing on the River Thames in the south east of the island of Great Britain and it was founded by the Romans, who named it Londinium. Londons ancient core, the City of London, largely retains its 1. 12-square-mile medieval boundaries. London is a global city in the arts, commerce, education, entertainment, fashion, finance, healthcare, media, professional services, research and development, tourism. It is crowned as the worlds largest financial centre and has the fifth- or sixth-largest metropolitan area GDP in the world, London is a world cultural capital. It is the worlds most-visited city as measured by international arrivals and has the worlds largest city airport system measured by passenger traffic, London is the worlds leading investment destination, hosting more international retailers and ultra high-net-worth individuals than any other city. Londons universities form the largest concentration of education institutes in Europe. In 2012, London became the first city to have hosted the modern Summer Olympic Games three times, London has a diverse range of people and cultures, and more than 300 languages are spoken in the region. Its estimated mid-2015 municipal population was 8,673,713, the largest of any city in the European Union, Londons urban area is the second most populous in the EU, after Paris, with 9,787,426 inhabitants at the 2011 census. The citys metropolitan area is the most populous in the EU with 13,879,757 inhabitants, the city-region therefore has a similar land area and population to that of the New York metropolitan area. London was the worlds most populous city from around 1831 to 1925, Other famous landmarks include Buckingham Palace, the London Eye, Piccadilly Circus, St Pauls Cathedral, Tower Bridge, Trafalgar Square, and The Shard. The London Underground is the oldest underground railway network in the world, the etymology of London is uncertain. It is an ancient name, found in sources from the 2nd century and it is recorded c.121 as Londinium, which points to Romano-British origin, and hand-written Roman tablets recovered in the city originating from AD 65/70-80 include the word Londinio. The earliest attempted explanation, now disregarded, is attributed to Geoffrey of Monmouth in Historia Regum Britanniae and this had it that the name originated from a supposed King Lud, who had allegedly taken over the city and named it Kaerlud. From 1898, it was accepted that the name was of Celtic origin and meant place belonging to a man called *Londinos. The ultimate difficulty lies in reconciling the Latin form Londinium with the modern Welsh Llundain, which should demand a form *lōndinion, from earlier *loundiniom. The possibility cannot be ruled out that the Welsh name was borrowed back in from English at a later date, and thus cannot be used as a basis from which to reconstruct the original name. Until 1889, the name London officially applied only to the City of London, two recent discoveries indicate probable very early settlements near the Thames in the London area
31.
Royal Society
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Founded in November 1660, it was granted a royal charter by King Charles II as The Royal Society. The society is governed by its Council, which is chaired by the Societys President, according to a set of statutes and standing orders. The members of Council and the President are elected from and by its Fellows, the members of the society. As of 2016, there are about 1,600 fellows, allowed to use the postnominal title FRS, there are also royal fellows, honorary fellows and foreign members, the last of which are allowed to use the postnominal title ForMemRS. The Royal Society President is Venkatraman Ramakrishnan, who took up the post on 30 November 2015, since 1967, the society has been based at 6–9 Carlton House Terrace, a Grade I listed building in central London which was previously used by the Embassy of Germany, London. The Royal Society started from groups of physicians and natural philosophers, meeting at variety of locations and they were influenced by the new science, as promoted by Francis Bacon in his New Atlantis, from approximately 1645 onwards. A group known as The Philosophical Society of Oxford was run under a set of rules still retained by the Bodleian Library, after the English Restoration, there were regular meetings at Gresham College. It is widely held that these groups were the inspiration for the foundation of the Royal Society, I will not say, that Mr Oldenburg did rather inspire the French to follow the English, or, at least, did help them, and hinder us. But tis well known who were the men that began and promoted that design. This initial royal favour has continued and, since then, every monarch has been the patron of the society, the societys early meetings included experiments performed first by Hooke and then by Denis Papin, who was appointed in 1684. These experiments varied in their area, and were both important in some cases and trivial in others. The Society returned to Gresham in 1673, there had been an attempt in 1667 to establish a permanent college for the society. Michael Hunter argues that this was influenced by Solomons House in Bacons New Atlantis and, to a lesser extent, by J. V. The first proposal was given by John Evelyn to Robert Boyle in a letter dated 3 September 1659, he suggested a scheme, with apartments for members. The societys ideas were simpler and only included residences for a handful of staff and these plans were progressing by November 1667, but never came to anything, given the lack of contributions from members and the unrealised—perhaps unrealistic—aspirations of the society. During the 18th century, the gusto that had characterised the early years of the society faded, with a number of scientific greats compared to other periods. The pointed lightning conductor had been invented by Benjamin Franklin in 1749, during the same time period, it became customary to appoint society fellows to serve on government committees where science was concerned, something that still continues. The 18th century featured remedies to many of the early problems
32.
Electrolysis
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In chemistry and manufacturing, electrolysis is a technique that uses a direct electric current to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as using an electrolytic cell. The voltage that is needed for electrolysis to occur is called the decomposition potential, nevertheless, electrolysis, as a tool to study chemical reactions and obtain pure elements, precedes the coinage of the term and formal description by Faraday. 1785 – Martinus van Marums electrostatic generator was used to reduce tin, zinc,1800 – William Nicholson and Anthony Carlisle, decomposed water into hydrogen and oxygen. 1808 – Potassium, sodium, barium, calcium and magnesium were discovered by Sir Humphry Davy using electrolysis,1821 – Lithium was discovered by the English chemist William Thomas Brande, who obtained it by electrolysis of lithium oxide. 1833 – Michael Faraday develops his two laws of electrolysis, and provides an explanation of his laws. 1875 – Paul Émile Lecoq de Boisbaudran discovered gallium using electrolysis,1886 – Fluorine was discovered by Henri Moissan using electrolysis. The main components required to achieve electrolysis are, An electrolyte, a substance, frequently an ion-conducting polymer that contains free ions, if the ions are not mobile, as in a solid salt then electrolysis cannot occur. A direct current electrical supply, provides the necessary to create or discharge the ions in the electrolyte. Electric current is carried by electrons in the external circuit, two electrodes, electrical conductors that provide the physical interface between the electrolyte and the electrical circuit that provides the energy. Electrodes of metal, graphite and semiconductor material are widely used, choice of suitable electrode depends on chemical reactivity between the electrode and electrolyte and manufacturing cost. The key process of electrolysis is the interchange of atoms and ions by the removal or addition of electrons from the external circuit, the desired products of electrolysis are often in a different physical state from the electrolyte and can be removed by some physical processes. For example, in the electrolysis of brine to produce hydrogen and chlorine and these gaseous products bubble from the electrolyte and are collected. Each electrode attracts ions that are of the opposite charge, positively charged ions move towards the electron-providing cathode. Negatively charged ions move towards the electron-extracting anode, in this process electrons are either absorbed or released. Neutral atoms gain or lose electrons and become charged ions that pass into the electrolyte. The formation of uncharged atoms from ions is called discharging, when an ion gains or loses enough electrons to become uncharged atoms, the newly formed atoms separate from the electrolyte. Positive metal ions like Cu++ deposit onto the cathode in a layer, the terms for this are electroplating, electrowinning, and electrorefining
33.
Electromotive force
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Electromotive force, also called emf, is the voltage developed by any source of electrical energy such as a battery or dynamo. It is generally defined as the potential for a source in a circuit. A device that supplies electrical energy is called electromotive force or emf, emfs convert chemical, mechanical, and other forms of energy into electrical energy. The product of such a device is known as emf. The word force in case is not used to mean mechanical force, measured in newtons. In electromagnetic induction, emf can be defined around a loop as the electromagnetic work that would be done on a charge if it travels once around that loop. This potential difference can drive a current if a circuit is attached to the terminals. Devices that can provide emf include electrochemical cells, thermoelectric devices, solar cells, photodiodes, electrical generators, transformer, in nature, emf is generated whenever magnetic field fluctuations occur through a surface. The shifting of the Earths magnetic field during a geomagnetic storm, … By chemical, mechanical or other means, the source of emf performs work dW on that charge to move it to the high potential terminal. The emf ℰ of the source is defined as the work dW done per charge dq, in the open-circuit case, charge separation continues until the electrical field from the separated charges is sufficient to arrest the reactions. Again the emf is countered by the voltage due to charge separation. If a load is attached, this voltage can drive a current, the general principle governing the emf in such electrical machines is Faradays law of induction. Electromotive force is often denoted by E or ℰ, in a device without internal resistance, if an electric charge Q passes through that device, and gains an energy W, the net emf for that device is the energy gained per unit charge, or J/Q. Like other measures of energy per charge, emf has SI units of volts, Electromotive force in electrostatic units is the statvolt. Inside a source of emf that is open-circuited, the electrostatic field created by separation of charge exactly cancels the forces producing the emf. Thus, the emf has the same value but opposite sign as the integral of the field aligned with an internal path between two terminals A and B of a source of emf in open-circuit condition. This equation applies only to locations A and B that are terminals and this equation involves the electrostatic electric field due to charge separation Ecs and does not involve any non-conservative component of electric field due to Faradays law of induction. The electrostatic field does not contribute to the net emf around a circuit because the portion of the electric field is conservative
34.
William Hyde Wollaston
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William Hyde Wollaston PRS was an English chemist and physicist who is famous for discovering the chemical elements palladium and rhodium. He also developed a way to process ore into malleable ingots. Wollaston was born in East Dereham, Norfolk, the son of the priest-astronomer Francis Wollaston, the family, which included 17 children, was financially well-off and were part of an intellectually stimulating environment. He worked as a physician in rural areas between 1793 and 1797, then moved to London, during his studies, Wollaston had become interested in chemistry, crystallography, metallurgy and physics. In 1800, after he had received a sum of money from one of his older brothers. He concentrated on pursuing his interests in chemistry and other subjects outside his trained vocation and he was elected a Fellow of the Royal Society in 1793, where he became an influential member. He served as president in 1820, in 1822 he was elected a Foreign Honorary Member of the American Academy of Arts and Sciences. He died in London in 1828 and was buried in Chislehurst, chemical analysis related to the process of purifying platinum led Wollaston to discover the elements palladium in 1802 and rhodium in 1804. Anders Gustav Ekeberg discovered tantalum in 1802, however, Wollaston declared it was identical with niobium, later Heinrich Rose proved in 1846 that columbium and tantalum were indeed different elements and he renamed columbium niobium. The mineral wollastonite was later named after Wollaston for his contributions to crystallography, Wollaston also performed important work in electricity. In 1801, he performed an experiment showing that the electricity from friction was identical to that produced by voltaic piles, controversy erupted when Michael Faraday constructed the first working electric motor and hastily published his results without acknowledging Wollastons previous work. Wollaston, however, saw nothing wrong with Faradays action and his optical work was important as well, where he is remembered for his observations of dark Fraunhofer lines in the solar spectrum, which eventually led to the discovery of the elements in the Sun. He invented the camera lucida, the goniometer, and the Wollaston prism. He also developed the first lens specifically for camera lens called Wollastons meniscus lens, or just meniscus lens, the lens was designed to improve the image projected by the camera obscura. By changing the shape of the lens, Wollaston was able to project a flatter image, Wollaston also devised a cryophorus, a glass container containing liquid water and water vapor. It is used in courses to demonstrate rapid freezing by evaporation. He used his Bakerian lecture in 1805, On the Force of Percussion, to defend Gottfried Leibnizs principle of vis viva, Wollastons attempt to demonstrate the presence of glucose in the blood serum of diabetics was unsuccessful due to the limited means of detection available to him. Wollaston supported this theory by referring to the thesis of a medical student at Edinburgh, Charles Darwin
35.
Friction
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Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction, Dry friction resists relative lateral motion of two surfaces in contact. Dry friction is subdivided into static friction between non-moving surfaces, and kinetic friction between moving surfaces, fluid friction describes the friction between layers of a viscous fluid that are moving relative to each other. Lubricated friction is a case of fluid friction where a lubricant fluid separates two solid surfaces, skin friction is a component of drag, the force resisting the motion of a fluid across the surface of a body. Internal friction is the force resisting motion between the making up a solid material while it undergoes deformation. When surfaces in contact move relative to other, the friction between the two surfaces converts kinetic energy into thermal energy. This property can have consequences, as illustrated by the use of friction created by rubbing pieces of wood together to start a fire. Kinetic energy is converted to thermal energy whenever motion with friction occurs, another important consequence of many types of friction can be wear, which may lead to performance degradation and/or damage to components. Friction is a component of the science of tribology, Friction is not itself a fundamental force. Dry friction arises from a combination of adhesion, surface roughness, surface deformation. The complexity of interactions makes the calculation of friction from first principles impractical and necessitates the use of empirical methods for analysis. Friction is a non-conservative force - work done against friction is path dependent, in the presence of friction, some energy is always lost in the form of heat. Thus mechanical energy is not conserved, the Greeks, including Aristotle, Vitruvius, and Pliny the Elder, were interested in the cause and mitigation of friction. They were aware of differences between static and kinetic friction with Themistius stating in 350 A. D. that it is easier to further the motion of a moving body than to move a body at rest. The classic laws of sliding friction were discovered by Leonardo da Vinci in 1493, a pioneer in tribology and these laws were rediscovered by Guillaume Amontons in 1699. Amontons presented the nature of friction in terms of surface irregularities, the understanding of friction was further developed by Charles-Augustin de Coulomb. Coulomb further considered the influence of sliding velocity, temperature and humidity, the distinction between static and dynamic friction is made in Coulombs friction law, although this distinction was already drawn by Johann Andreas von Segner in 1758. Leslie was equally skeptical about the role of adhesion proposed by Desaguliers, in Leslies view, friction should be seen as a time-dependent process of flattening, pressing down asperities, which creates new obstacles in what were cavities before
36.
Vasily Vladimirovich Petrov
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Vasily Vladimirovich Petrov was a Russian experimental physicist, self-taught electrical technician, academician of Russian Academy of Sciences. Vasily Petrov was born in the town of Oboyan in the family of a priest and he studied at a public school in Kharkov, and then at the St. Petersburg Teachers College. In 1788, he gained a position as mathematics and physics teacher at Kolyvansko-Voskresenskoe College of Mining, in 1791, he was transferred to Saint Petersburg to teach mathematics and Russian at the military Engineering College, in the Izmailovsky regiment. In 1793, Petrov was invited to teach mathematics and physics at the St. Petersburg Medical and Surgery School, in 1795, he was promoted to the rank of Extraordinary Professor. During the next few years, he built up a physics laboratory. His first published book, A collection of new physical-chemical experiments, the bulk of this work was dedicated to the description of experiments related to combustion, as evidence against the then-popular phlogiston theory. The chapters, describing luminosity of phosphors of mineral and organic origins have elicited vivid interest in scientific circles. In 1802, Petrov discovered the electric arc effect, thanks to his building the worlds largest and most powerful Voltaic pile at the time, Petrov was forgotten soon after his death and his works fell into oblivion. A copy of News of Galvanic-Voltaic Experiments was discovered by chance in a library in the town of Vilno near the end of the 19th century, the book was the first time in world literature that a series of important physical phenomena related to electricity were described in detail. It was not until the late 1880s that technology based on Petrovs experiments was developed with the goal of industrial usage, menschutkin, Boris N. Vasilij Vladimirovic Petrov and His Physico-Chemical Work. Rise of Science in Russia 1700-1917
37.
Electric arc
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An electric arc or arc discharge is an electrical breakdown of a gas that produces an ongoing electrical discharge. The current through a normally nonconductive medium such as air produces a plasma, an arc discharge is characterized by a lower voltage than a glow discharge, and it relies on thermionic emission of electrons from the electrodes supporting the arc. An archaic term is voltaic arc, as used in the voltaic arc lamp. The phenomenon is believed to be first described by Sir Humphry Davy in an 1801 paper published in William Nicholsons Journal of Natural Philosophy, Chemistry and the Arts. However, Davys description was not an arc as this phenomenon is considered by the modern science, This is evidently the description, not of an arc. For the essence of an arc is that it should be continuous, in the same year Davy publicly demonstrated the effect, before the Royal Society, by transmitting an electric current through two touching carbon rods and then pulling them a short distance apart. The demonstration produced a feeble arc, not readily distinguished from a sustained spark, the Society subscribed for a more powerful battery of 1000 plates and in 1808 he demonstrated the large-scale arc. He is credited with naming the arc and he called it an arc because it assumes the shape of an upward bow when the distance between the electrodes is not small. This is due to the buoyant force on the hot gas, in the late nineteenth century, electric arc lighting was in wide use for public lighting. The tendency of electric arcs to flicker and hiss was a major problem, in 1895, Hertha Marks Ayrton wrote a series of articles for the Electrician, explaining that these phenomena were the result of oxygen coming into contact with the carbon rods used to create the arc. In 1899, she was the first woman ever to read her own paper before the Institution of Electrical Engineers and her paper was entitled The Hissing of the Electric Arc. Shortly thereafter, Ayrton was elected the first female member of the IEE and she petitioned to present a paper before the Royal Society but was not allowed because of her sex, and The Mechanism of the Electric Arc was read by John Perry in her stead in 1901. An electric arc is the form of discharge with the highest current density. The maximum current through an arc is limited only by the external circuit, an arc between two electrodes can be initiated by ionization and glow discharge, as the current through the electrodes is increased. The breakdown voltage of the gap is a function of the pressure. When an arc starts, its voltage is much less than a glow discharge. An arc in gases near atmospheric pressure is characterized by light emission, high current density. A drawn arc can be initiated by two electrodes initially in contact and drawn apart, this can initiate an arc without the high-voltage glow discharge
38.
Andrew Crosse
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For the VFL player, see Andrew Cross. Andrew Crosse was a British amateur scientist who was born and died at Fyne Court, Broomfield, Crosse was an early pioneer and experimenter in the use of electricity. He became widely known after press reports of an experiment he conducted in 1836. Crosse was the first son of Richard Crosse and Susannah Porter, in 1788 he accompanied them on a trip to France, where he went to school for a time in Orléans. From the age of six until he was eight he stayed with a tutor, the Reverend Mr White, in Dorchester, on 1 February 1792 he was sent to boarding school in Bristol. Around the age of 12 Crosse persuaded one of his teachers to let him attend a series of lectures on the natural sciences and this led to his lifelong interest in the subject. Crosse first started experimenting with electricity during his time in the sixth form, after leaving school he studied at Brasenose College, Oxford. Having lost his parents, his father in 1800 and his mother in 1805, after abandoning his studies for the Bar, he increasingly devoted his spare time to studying electricity at Fyne Court, where he built his own laboratory. He also studied mineralogy and became interested in the formation of deposits in caves. Around 1807 he started to experiment with electrocrystallization, forming crystalline lime carbonate from water taken from Holwell Cavern and he returned to the subject again from around 1817 and in subsequent years produced a total of 24 electrocrystallized minerals. Using this wire he was able to determine the polarity of the atmosphere under various weather conditions and his results were published by his friend George Singer in 1814, as part of Singers Elements of Electricity and Electro-Chemistry. Along with Sir Humphry Davy, Crosse was one of the first to develop large voltaic piles, although it was not the largest he built, Henry Minchin Noads Manual of Electricity describes a battery consisting of 50 jars containing 73 square feet of coated surface. Using his wires Crosse was able to charge and discharge it some 20 times a minute and he became known locally as the thunder and lightning man. In 1836 Sir Richard Phillips described seeing a variety of voltaic piles at Fyne Court, totalling 2,500. In 1836 Crosse was persuaded to attend a meeting of the British Association for the Advancement of Science in Bristol. After describing his discoveries over dinner at the house of a friend in Bristol and they included his electrocrystallization and atmospheric experiments, and his improvements to the voltaic battery. He was also interested in the uses of electricity and magnetism, including the development of loudspeakers. More creatures appeared and two later they began moving their legs
39.
Royal Institution
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The Royal Institution of Great Britain is an organisation devoted to scientific education and research, based in London. Since its founding it has based at 21 Albemarle Street in Mayfair. Its Royal Charter was granted in 1800, throughout its history, the Institution has supported public engagement with science through a program of lectures, many of which continue today. The most famous of these are the annual Royal Institution Christmas Lectures, the Institution has had an instrumental role in the advancement of science since its founding. In the 19th century, Faraday carried out much of the research which laid the groundwork for the exploitation of electricity at the Royal Institution. In total fifteen scientists attached to the Royal Institution have won Nobel Prizes, the leadership of the Royal Institution has had various titles, Director of the Laboratory Director of the Davy-Faraday Research Laboratory Director The position was abolished in 2010. The Institutions last director was Susan Greenfield, following various resignations and general meetings of members, Andrade was awarded £7,000 by arbitration, the arbitrators blamed the problems on a lack of clear definition of roles. An outdated constitution, and the inability of the protagonists to compromise, Andrade launched a lawsuit to set the arbitration aside, which he lost. From 1998 to 8 January 2010, the director of the Royal Institution was Baroness Susan Greenfield, but following a review, the project ended £3 million in debt. Greenfield subsequently announced that she would be suing for discrimination, Baroness Greenfield later dropped the discrimination case. Today the Royal Institution is committed to diffusing science for the purposes of life. Membership is open to all, with no nomination procedure or academic requirements, the institutions palatial home has been greatly enlarged and redeveloped since 1799, and is a Grade I listed building. The structures last refurbishment was a £22 million project completed in 2008, as well as the famous Lecture Theatre, the building contains several function rooms, modern research facilities and a public café. The trustees were considering selling the building in an effort to recoup the organisations debts, in 2013 The Ri received an anonymous donation of £4. 4m and as of January 2016, the Ri is now debt-free. The Institution has a public science programme and science for schools programme. The Christmas Lectures continue today as a series of three televised lectures aimed at children, the Friday Evening Discourses are monthly lectures given by eminent scientists, each limited to exactly one hour, a tradition started by Faraday. There is a members ballot for tickets to the Christmas Lectures. Discounts are available to Ri Patrons and Members, many other events and lectures are held both at Albemarle Street and at other venues around the country
40.
Michael Faraday
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Michael Faraday FRS was an English scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic induction, diamagnetism, although Faraday received little formal education, he was one of the most influential scientists in history. It was by his research on the field around a conductor carrying a direct current that Faraday established the basis for the concept of the electromagnetic field in physics. Faraday also established that magnetism could affect rays of light and that there was a relationship between the two phenomena. He similarly discovered the principles of induction and diamagnetism. His inventions of electromagnetic rotary devices formed the foundation of electric motor technology, Faraday ultimately became the first and foremost Fullerian Professor of Chemistry at the Royal Institution of Great Britain, a lifetime position. James Clerk Maxwell took the work of Faraday and others and summarized it in a set of equations which is accepted as the basis of all theories of electromagnetic phenomena. The SI unit of capacitance is named in his honour, the farad, albert Einstein kept a picture of Faraday on his study wall, alongside pictures of Isaac Newton and James Clerk Maxwell. Faraday was born in Newington Butts, which is now part of the London Borough of Southwark but was then a part of Surrey. His family was not well off and his father, James, was a member of the Glassite sect of Christianity. James Faraday moved his wife and two children to London during the winter of 1790 from Outhgill in Westmorland, where he had been an apprentice to the village blacksmith, Michael was born in the autumn of that year. The young Michael Faraday, who was the third of four children, at the age of 14 he became an apprentice to George Riebau, a local bookbinder and bookseller in Blandford Street. During his seven-year apprenticeship Faraday read many books, including Isaac Wattss The Improvement of the Mind, at this time he also developed an interest in science, especially in electricity. Faraday was particularly inspired by the book Conversations on Chemistry by Jane Marcet, many of the tickets for these lectures were given to Faraday by William Dance, who was one of the founders of the Royal Philharmonic Society. Faraday subsequently sent Davy a 300-page book based on notes that he had taken during these lectures, davys reply was immediate, kind, and favourable. In 1813, when Davy damaged his eyesight in an accident with nitrogen trichloride, very soon Davy entrusted Faraday with the preparation of nitrogen trichloride samples, and they both were injured in an explosion of this very sensitive substance. In the class-based English society of the time, Faraday was not considered a gentleman, Faraday was forced to fill the role of valet as well as assistant throughout the trip. Davys wife, Jane Apreece, refused to treat Faraday as an equal, the trip did, however, give him access to the scientific elite of Europe and exposed him to a host of stimulating ideas
41.
Electrochemistry
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These reactions involve electric charges moving between electrodes and an electrolyte. Thus electrochemistry deals with the interaction between electrical energy and chemical change, chemical reactions where electrons are transferred directly between molecules and/or atoms are called oxidation-reduction or reactions. In general, electrochemistry describes the reactions when individual redox reactions are separate but connected by an external electric circuit. Understanding of electrical matters began in the sixteenth century, during this century, the English scientist William Gilbert spent 17 years experimenting with magnetism and, to a lesser extent, electricity. For his work on magnets, Gilbert became known as the Father of Magnetism and he discovered various methods for producing and strengthening magnets. In 1663, the German physicist Otto von Guericke created the first electric generator, the generator was made of a large sulfur ball cast inside a glass globe, mounted on a shaft. The ball was rotated by means of a crank and a spark was produced when a pad was rubbed against the ball as it rotated. The globe could be removed and used as source for experiments with electricity, by the mid—18th century the French chemist Charles François de Cisternay du Fay had discovered two types of static electricity, and that like charges repel each other whilst unlike charges attract. Du Fay announced that electricity consisted of two fluids, vitreous, or positive, electricity, and resinous, or negative, electricity and this was the two-fluid theory of electricity, which was to be opposed by Benjamin Franklins one-fluid theory later in the century. Galvani refuted this by obtaining muscular action with two pieces of the same material, in 1800, William Nicholson and Johann Wilhelm Ritter succeeded in decomposing water into hydrogen and oxygen by electrolysis. Soon thereafter Ritter discovered the process of electroplating and he also observed that the amount of metal deposited and the amount of oxygen produced during an electrolytic process depended on the distance between the electrodes. By 1801, Ritter observed thermoelectric currents and anticipated the discovery of thermoelectricity by Thomas Johann Seebeck, by the 1810s, William Hyde Wollaston made improvements to the galvanic cell. This work led directly to the isolation of sodium and potassium from their compounds, andré-Marie Ampère quickly repeated Ørsteds experiment, and formulated them mathematically. In 1821, Estonian-German physicist Thomas Johann Seebeck demonstrated the potential in the juncture points of two dissimilar metals when there is a heat difference between the joints. In 1827, the German scientist Georg Ohm expressed his law in this famous book Die galvanische Kette, in 1832, Michael Faradays experiments led him to state his two laws of electrochemistry. In 1836, John Daniell invented a primary cell which solved the problem of polarization by eliminating hydrogen gas generation at the positive electrode, later results revealed that alloying the amalgamated zinc with mercury would produce a higher voltage. William Grove produced the first fuel cell in 1839, in 1846, Wilhelm Weber developed the electrodynamometer. In 1868, Georges Leclanché patented a new cell which became the forerunner to the worlds first widely used battery
42.
Johann Wilhelm Ritter
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Johann Wilhelm Ritter was a German chemist, physicist and philosopher. He was born in Samitz near Haynau in Silesia, and died in Munich, Johann Wilhelm Ritters first involvement with science began when he was 14 years old. He became an apprentice to an apothecary in Liegnitz, and acquired a deep interest in chemistry and he began medicine studies at the University of Jena in 1796. A self-taught scientist, he made many researches on chemistry, electricity. Ritter belonged to the German Romantic movement and he was personally acquainted with Johann Wolfgang von Goethe, Alexander von Humboldt, Johann Gottfried Herder and Clemens Brentano. He was strongly influenced by Friedrich Wilhelm Joseph Schelling, who was the philosopher of the Naturphilosophie movement. In 1801, Hans Christian Ørsted visited Jena and became his friend, several of Ritters researches were latter reported by Ørsted, who was also strongly influenced by the philosophical outlook of Naturphilosophie. Ritters first scientific researches concerned some galvanic phenomena and he interpreted the physiological effects observed by Luigi Galvani and other researchers as due to the electricity generated by chemical reactions. His interpretation is closer to the one accepted nowadays than those proposed by Galvani and Alessandro Volta, in 1800, shortly after the invention of the voltaic pile, William Nicholson and Anthony Carlisle discovered that water could be decomposed by electricity. Shortly afterward, Ritter also discovered the effect, independently. Besides that, he collected and measured the amounts of hydrogen and oxygen produced in the reaction and he also discovered the process of electroplating. In 1802 he built his first electrochemical cell, with 50 copper discs separated by cardboard disks moistened by a salt solution, Ritter made several self-experiments applying the poles of a voltaic pile to his own hands, eyes, ears, nose and tongue. He also described the difference between the effects of the two poles of the pile, although some of the effects he reported were not confirmed afterwards. Many of Ritters researches were guided by a search for polarities in the forces of nature. In 1801, after hearing about the discovery of heat rays by William Herschel, the chemical rays found by him were afterwards called ultraviolet radiation. Some of Ritters researches were acknowledged as important scientific contributions, Ritter had no regular income and never became a university professor, although in 1804 he was elected a member of the Bavarian Academy of Science. He married in 1804 and had four children, but he was unable to provide the needs of his family, plagued by financial difficulties and suffering from weak health, he died young in 1810, as a poor man. Toward an Archaeology of Hearing and Seeing by Technical Means, ISBN 978-0-262-74032-6
43.
Zamboni pile
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The Zamboni pile is an early electric battery, invented by Giuseppe Zamboni in 1812. A Zamboni pile is a battery and is constructed from discs of silver foil, zinc foil. Alternatively, discs of silver paper gilded on one side or silver paper smeared with manganese oxide, Zamboni piles of more modern construction were manufactured as recently as the 1980s for providing the accelerating voltage for image intensifier tubes, particularly in military use. Today such voltages are obtained from transistorised inverter circuits powered by conventional batteries, the EMF per element is approximately 0.8 volts, with thousands of stacked elements, Zamboni piles have output potential differences in the kilovolt range, but current output in the nanoampere range. The famous Oxford Electric Bell, which has been ringing continuously since 1840, is thought to be powered by a pair of Zamboni piles
44.
Hydrogen
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Hydrogen is a chemical element with chemical symbol H and atomic number 1. With a standard weight of circa 1.008, hydrogen is the lightest element on the periodic table. Its monatomic form is the most abundant chemical substance in the Universe, non-remnant stars are mainly composed of hydrogen in the plasma state. The most common isotope of hydrogen, termed protium, has one proton, the universal emergence of atomic hydrogen first occurred during the recombination epoch. At standard temperature and pressure, hydrogen is a colorless, odorless, tasteless, non-toxic, nonmetallic, since hydrogen readily forms covalent compounds with most nonmetallic elements, most of the hydrogen on Earth exists in molecular forms such as water or organic compounds. Hydrogen plays an important role in acid–base reactions because most acid-base reactions involve the exchange of protons between soluble molecules. In ionic compounds, hydrogen can take the form of a charge when it is known as a hydride. The hydrogen cation is written as though composed of a bare proton, Hydrogen gas was first artificially produced in the early 16th century by the reaction of acids on metals. Industrial production is mainly from steam reforming natural gas, and less often from more energy-intensive methods such as the electrolysis of water. Most hydrogen is used near the site of its production, the two largest uses being fossil fuel processing and ammonia production, mostly for the fertilizer market, Hydrogen is a concern in metallurgy as it can embrittle many metals, complicating the design of pipelines and storage tanks. Hydrogen gas is flammable and will burn in air at a very wide range of concentrations between 4% and 75% by volume. The enthalpy of combustion is −286 kJ/mol,2 H2 + O2 →2 H2O +572 kJ Hydrogen gas forms explosive mixtures with air in concentrations from 4–74%, the explosive reactions may be triggered by spark, heat, or sunlight. The hydrogen autoignition temperature, the temperature of spontaneous ignition in air, is 500 °C, the detection of a burning hydrogen leak may require a flame detector, such leaks can be very dangerous. Hydrogen flames in other conditions are blue, resembling blue natural gas flames, the destruction of the Hindenburg airship was a notorious example of hydrogen combustion and the cause is still debated. The visible orange flames in that incident were the result of a mixture of hydrogen to oxygen combined with carbon compounds from the airship skin. H2 reacts with every oxidizing element, the ground state energy level of the electron in a hydrogen atom is −13.6 eV, which is equivalent to an ultraviolet photon of roughly 91 nm wavelength. The energy levels of hydrogen can be calculated fairly accurately using the Bohr model of the atom, however, the atomic electron and proton are held together by electromagnetic force, while planets and celestial objects are held by gravity. The most complicated treatments allow for the effects of special relativity
45.
Ion
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An ion is an atom or a molecule in which the total number of electrons is not equal to the total number of protons, giving the atom or molecule a net positive or negative electrical charge. Ions can be created, by chemical or physical means. In chemical terms, if an atom loses one or more electrons. If an atom gains electrons, it has a net charge and is known as an anion. Ions consisting of only a single atom are atomic or monatomic ions, because of their electric charges, cations and anions attract each other and readily form ionic compounds, such as salts. In the case of ionization of a medium, such as a gas, which are known as ion pairs are created by ion impact, and each pair consists of a free electron. The word ion comes from the Greek word ἰόν, ion, going and this term was introduced by English physicist and chemist Michael Faraday in 1834 for the then-unknown species that goes from one electrode to the other through an aqueous medium. Faraday also introduced the words anion for a charged ion. In Faradays nomenclature, cations were named because they were attracted to the cathode in a galvanic device, arrhenius explanation was that in forming a solution, the salt dissociates into Faradays ions. Arrhenius proposed that ions formed even in the absence of an electric current, ions in their gas-like state are highly reactive, and do not occur in large amounts on Earth, except in flames, lightning, electrical sparks, and other plasmas. These gas-like ions rapidly interact with ions of charge to give neutral molecules or ionic salts. These stabilized species are commonly found in the environment at low temperatures. A common example is the present in seawater, which are derived from the dissolved salts. Electrons, due to their mass and thus larger space-filling properties as matter waves, determine the size of atoms. Thus, anions are larger than the parent molecule or atom, as the excess electron repel each other, as such, in general, cations are smaller than the corresponding parent atom or molecule due to the smaller size of its electron cloud. One particular cation contains no electrons, and thus consists of a single proton - very much smaller than the parent hydrogen atom. Since the electric charge on a proton is equal in magnitude to the charge on an electron, an anion, from the Greek word ἄνω, meaning up, is an ion with more electrons than protons, giving it a net negative charge. A cation, from the Greek word κατά, meaning down, is an ion with fewer electrons than protons, there are additional names used for ions with multiple charges
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Electron
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The electron is a subatomic particle, symbol e− or β−, with a negative elementary electric charge. Electrons belong to the first generation of the lepton particle family, the electron has a mass that is approximately 1/1836 that of the proton. Quantum mechanical properties of the include a intrinsic angular momentum of a half-integer value, expressed in units of the reduced Planck constant. As it is a fermion, no two electrons can occupy the same state, in accordance with the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of particles and waves, they can collide with other particles and can be diffracted like light. Since an electron has charge, it has an electric field. Electromagnetic fields produced from other sources will affect the motion of an electron according to the Lorentz force law, electrons radiate or absorb energy in the form of photons when they are accelerated. Laboratory instruments are capable of trapping individual electrons as well as electron plasma by the use of electromagnetic fields, special telescopes can detect electron plasma in outer space. Electrons are involved in applications such as electronics, welding, cathode ray tubes, electron microscopes, radiation therapy, lasers, gaseous ionization detectors. Interactions involving electrons with other particles are of interest in fields such as chemistry. The Coulomb force interaction between the positive protons within atomic nuclei and the negative electrons without, allows the composition of the two known as atoms, ionization or differences in the proportions of negative electrons versus positive nuclei changes the binding energy of an atomic system. The exchange or sharing of the electrons between two or more atoms is the cause of chemical bonding. In 1838, British natural philosopher Richard Laming first hypothesized the concept of a quantity of electric charge to explain the chemical properties of atoms. Irish physicist George Johnstone Stoney named this charge electron in 1891, electrons can also participate in nuclear reactions, such as nucleosynthesis in stars, where they are known as beta particles. Electrons can be created through beta decay of isotopes and in high-energy collisions. The antiparticle of the electron is called the positron, it is identical to the electron except that it carries electrical, when an electron collides with a positron, both particles can be totally annihilated, producing gamma ray photons. The ancient Greeks noticed that amber attracted small objects when rubbed with fur, along with lightning, this phenomenon is one of humanitys earliest recorded experiences with electricity. In his 1600 treatise De Magnete, the English scientist William Gilbert coined the New Latin term electricus, both electric and electricity are derived from the Latin ēlectrum, which came from the Greek word for amber, ἤλεκτρον
