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.
Bunsen burner
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A Bunsen burner, named after Robert Bunsen, is a common piece of laboratory equipment that produces a single open gas flame, which is used for heating, sterilization, and combustion. The gas can be gas or a liquefied petroleum gas, such as propane, butane. In 1852 the University of Heidelberg hired Bunsen and promised him a new laboratory building, the city of Heidelberg had begun to install coal-gas street lighting, and so the university laid gas lines to the new laboratory. The designers of the building intended to use the gas not just for illumination, for any burner lamp, it was desirable to maximize the temperature and minimize luminosity. However, existing laboratory burner lamps left much to be desired not just in terms of the heat of the flame, but also regarding economy and simplicity. While the building was still under construction in late 1854 Bunsen suggested certain design principles to the mechanic, Peter Desaga. The Bunsen/Desaga design succeeded in generating a hot, sootless, non-luminous flame by mixing the gas with air in a controlled fashion before combustion, Desaga created adjustable slits for air at the bottom of the cylindrical burner, with the flame igniting at the top. By the time the building opened early in 1855 Desaga had made fifty of the burners for Bunsens students, two years later Bunsen published a description, and many of his colleagues soon adopted the design. Bunsen burners are now used in all around the world. The device in use today safely burns a continuous stream of a gas such as natural gas or a liquefied petroleum gas such as propane, butane. The hose barb is connected to a gas nozzle on the bench with rubber tubing. Most laboratory benches are equipped with multiple gas nozzles connected to a gas source, as well as vacuum, nitrogen. The gas then flows up through the base through a hole at the bottom of the barrel and is directed upward. There are open slots in the side of the bottom to admit air into the stream via the venturi effect. The most common methods of lighting the burner are using a match or a spark lighter, the amount of air mixed with the gas stream affects the completeness of the combustion reaction. Less air yields an incomplete and thus cooler reaction, while a gas stream well mixed with air provides oxygen in an amount and thus a complete. The air flow can be controlled by opening or closing the openings at the base of the barrel. If the collar at the bottom of the tube is adjusted so more air can mix with the gas before combustion, the flame will burn hotter, appearing blue as a result
3.
Chemistry
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Chemistry is a branch of physical science that studies the composition, structure, properties and change of matter. Chemistry is sometimes called the science because it bridges other natural sciences, including physics. For the differences between chemistry and physics see comparison of chemistry and physics, the history of chemistry can be traced to alchemy, which had been practiced for several millennia in various parts of the world. The word chemistry comes from alchemy, which referred to a set of practices that encompassed elements of chemistry, metallurgy, philosophy, astrology, astronomy, mysticism. An alchemist was called a chemist in popular speech, and later the suffix -ry was added to this to describe the art of the chemist as chemistry, the modern word alchemy in turn is derived from the Arabic word al-kīmīā. In origin, the term is borrowed from the Greek χημία or χημεία and this may have Egyptian origins since al-kīmīā is derived from the Greek χημία, which is in turn derived from the word Chemi or Kimi, which is the ancient name of Egypt in Egyptian. Alternately, al-kīmīā may derive from χημεία, meaning cast together, in retrospect, the definition of chemistry has changed over time, as new discoveries and theories add to the functionality of the science. The term chymistry, in the view of noted scientist Robert Boyle in 1661, in 1837, Jean-Baptiste Dumas considered the word chemistry to refer to the science concerned with the laws and effects of molecular forces. More recently, in 1998, Professor Raymond Chang broadened the definition of chemistry to mean the study of matter, early civilizations, such as the Egyptians Babylonians, Indians amassed practical knowledge concerning the arts of metallurgy, pottery and dyes, but didnt develop a systematic theory. Greek atomism dates back to 440 BC, arising in works by such as Democritus and Epicurus. In 50 BC, the Roman philosopher Lucretius expanded upon the theory in his book De rerum natura, unlike modern concepts of science, Greek atomism was purely philosophical in nature, with little concern for empirical observations and no concern for chemical experiments. Work, particularly the development of distillation, continued in the early Byzantine period with the most famous practitioner being the 4th century Greek-Egyptian Zosimos of Panopolis. He formulated Boyles law, rejected the four elements and proposed a mechanistic alternative of atoms. Before his work, though, many important discoveries had been made, the Scottish chemist Joseph Black and the Dutchman J. B. English scientist John Dalton proposed the theory of atoms, that all substances are composed of indivisible atoms of matter. Davy discovered nine new elements including the alkali metals by extracting them from their oxides with electric current, british William Prout first proposed ordering all the elements by their atomic weight as all atoms had a weight that was an exact multiple of the atomic weight of hydrogen. The inert gases, later called the noble gases were discovered by William Ramsay in collaboration with Lord Rayleigh at the end of the century, thereby filling in the basic structure of the table. Organic chemistry was developed by Justus von Liebig and others, following Friedrich Wöhlers synthesis of urea which proved that organisms were, in theory
4.
Metal
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A metal is a material that is typically hard, opaque, shiny, and has good electrical and thermal conductivity. Metals are generally malleable—that is, they can be hammered or pressed permanently out of shape without breaking or cracking—as well as fusible and ductile, about 91 of the 118 elements in the periodic table are metals, the others are nonmetals or metalloids. Some elements appear in both metallic and non-metallic forms, astrophysicists use the term metal to collectively describe all elements other than hydrogen and helium, the simplest two, in a star. The star fuses smaller atoms, mostly hydrogen and helium, to larger ones over its lifetime. In that sense, the metallicity of an object is the proportion of its matter made up of all chemical elements. Many elements and compounds that are not normally classified as metals become metallic under high pressures, the atoms of metallic substances are typically arranged in one of three common crystal structures, namely body-centered cubic, face-centered cubic, and hexagonal close-packed. In bcc, each atom is positioned at the center of a cube of eight others, in fcc and hcp, each atom is surrounded by twelve others, but the stacking of the layers differs. Some metals adopt different structures depending on the temperature, atoms of metals readily lose their outer shell electrons, resulting in a free flowing cloud of electrons within their otherwise solid arrangement. This provides the ability of metallic substances to easily transmit heat, while this flow of electrons occurs, the solid characteristic of the metal is produced by electrostatic interactions between each atom and the electron cloud. This type of bond is called a metallic bond, Metals are usually inclined to form cations through electron loss, reacting with oxygen in the air to form oxides over various timescales. Examples,4 Na + O2 →2 Na2O2 Ca + O2 →2 CaO4 Al +3 O2 →2 Al2O3, the transition metals are slower to oxidize because they form a passivating layer of oxide that protects the interior. Others, like palladium, platinum and gold, do not react with the atmosphere at all, some metals form a barrier layer of oxide on their surface which cannot be penetrated by further oxygen molecules and thus retain their shiny appearance and good conductivity for many decades. The oxides of metals are generally basic, as opposed to those of nonmetals, exceptions are largely oxides with very high oxidation states such as CrO3, Mn2O7, and OsO4, which have strictly acidic reactions. Painting, anodizing or plating metals are good ways to prevent their corrosion, however, a more reactive metal in the electrochemical series must be chosen for coating, especially when chipping of the coating is expected. Water and the two form an electrochemical cell, and if the coating is less reactive than the coatee. Metals in general have high conductivity, high thermal conductivity. Typically they are malleable and ductile, deforming under stress without cleaving, in terms of optical properties, metals are shiny and lustrous. Sheets of metal beyond a few micrometres in thickness appear opaque, although most metals have higher densities than most nonmetals, there is wide variation in their densities, lithium being the least dense solid element and osmium the densest
5.
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
6.
Chemical element
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A chemical element or element is a species of atoms having the same number of protons in their atomic nuclei. There are 118 elements that have identified, of which the first 94 occur naturally on Earth with the remaining 24 being synthetic elements. There are 80 elements that have at least one stable isotope and 38 that have exclusively radioactive isotopes, iron is the most abundant element making up Earth, while oxygen is the most common element in the Earths crust. Chemical elements constitute all of the matter of the universe. The two lightest elements, hydrogen and helium, were formed in the Big Bang and are the most common elements in the universe. The next three elements were formed mostly by cosmic ray spallation, and are rarer than those that follow. Formation of elements with from 6 to 26 protons occurred and continues to occur in main sequence stars via stellar nucleosynthesis, the high abundance of oxygen, silicon, and iron on Earth reflects their common production in such stars. The term element is used for atoms with a number of protons as well as for a pure chemical substance consisting of a single element. A single element can form multiple substances differing in their structure, when different elements are chemically combined, with the atoms held together by chemical bonds, they form chemical compounds. Only a minority of elements are found uncombined as relatively pure minerals, among the more common of such native elements are copper, silver, gold, carbon, and sulfur. All but a few of the most inert elements, such as gases and noble metals, are usually found on Earth in chemically combined form. While about 32 of the elements occur on Earth in native uncombined forms. For example, atmospheric air is primarily a mixture of nitrogen, oxygen, and argon, the history of the discovery and use of the elements began with primitive human societies that found native elements like carbon, sulfur, copper and gold. Later civilizations extracted elemental copper, tin, lead and iron from their ores by smelting, using charcoal, alchemists and chemists subsequently identified many more, almost all of the naturally occurring elements were known by 1900. Save for unstable radioactive elements with short half-lives, all of the elements are available industrially, almost all other elements found in nature were made by various natural methods of nucleosynthesis. On Earth, small amounts of new atoms are produced in nucleogenic reactions, or in cosmogenic processes. Of the 94 naturally occurring elements, those with atomic numbers 1 through 82 each have at least one stable isotope, Isotopes considered stable are those for which no radioactive decay has yet been observed. Elements with atomic numbers 83 through 94 are unstable to the point that radioactive decay of all isotopes can be detected, the very heaviest elements undergo radioactive decay with half-lives so short that they are not found in nature and must be synthesized
7.
Emission spectrum
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The photon energy of the emitted photon is equal to the energy difference between the two states. There are many possible electron transitions for each atom, and each transition has an energy difference. This collection of different transitions, leading to different radiated wavelengths, each elements emission spectrum is unique. Therefore, spectroscopy can be used to identify the elements in matter of unknown composition, similarly, the emission spectra of molecules can be used in chemical analysis of substances. The frequency of light emitted is a function of the energy of the transition, since energy must be conserved, the energy difference between the two states equals the energy carried off by the photon. The energy states of the transitions can lead to emissions over a large range of frequencies. For example, visible light is emitted by the coupling of states in atoms. On the other hand, nuclear shell transitions can emit high energy gamma rays, the emittance of an object quantifies how much light is emitted by it. This may be related to properties of the object through the Stefan–Boltzmann law. For most substances, the amount of emission varies with the temperature, precise measurements at many wavelengths allow the identification of a substance via emission spectroscopy. The quantum mechanics problem is treated using time-dependent perturbation theory and leads to the result known as Fermis golden rule. The description has been superseded by quantum electrodynamics, although the semi-classical version continues to be useful in most practical computations. When the electrons in the atom are excited, for example by being heated, when the electrons fall back down and leave the excited state, energy is re-emitted in the form of a photon. The wavelength of the photon is determined by the difference in energy between the two states and these emitted photons form the elements spectrum. The fact that certain colors appear in an elements atomic emission spectrum means that only certain frequencies of light are emitted. Each of these frequencies are related to energy by the formula, E photon = h ν, where E photon is the energy of the photon, ν is its frequency and this concludes that only photons with specific energies are emitted by the atom. The principle of the emission spectrum explains the varied colors in neon signs. The frequencies of light that an atom can emit are dependent on states the electrons can be in, when excited, an electron moves to a higher energy level or orbital
8.
Flame
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A flame is the visible, gaseous part of a fire. It is caused by a highly exothermic reaction taking place in a thin zone, very hot flames are hot enough to have ionized gaseous components of sufficient density to be considered plasma. Color and temperature of a flame are dependent on the type of fuel involved in the combustion, as, for example, the applied heat causes the fuel molecules in the candle wax to vaporize. In this state they can readily react with oxygen in the air. As the combustion temperature of a flame increases, so does the average energy of the radiation given off by the flame. Other oxidizers besides oxygen can be used to produce a flame, hydrogen burning in chlorine produces a flame and in the process emits gaseous hydrogen chloride as the combustion product. Another of many possible combinations is hydrazine and nitrogen tetroxide which is hypergolic. Fluoropolymers can be used to supply fluorine as an oxidizer of metallic fuels, the chemical kinetics occurring in the flame are very complex and typically involve a large number of chemical reactions and intermediate species, most of them radicals. For instance, a well-known chemical kinetics scheme, GRI-Mech, uses 53 species and 325 elementary reactions to describe combustion of biogas, there are different methods of distributing the required components of combustion to a flame. In a diffusion flame, oxygen and fuel diffuse into each other, in a premixed flame, the oxygen and fuel are premixed beforehand, which results in a different type of flame. Candle flames operate through evaporation of the fuel which rises in a flow of hot gas which then mixes with surrounding oxygen. In a laboratory under normal gravity conditions and with an oxygen valve. This is due to incandescence of very fine particles that are produced in the flame. The colder part of a flame will be red, transitioning to orange, yellow. For a given region, the closer to white on this scale. The transitions are often apparent in fires, in which the color emitted closest to the fuel is white, with a section above it. Specific colors can be imparted to the flame by introduction of species with bright emission spectrum lines. In analytical chemistry, this effect is used in tests to determine presence of some metal ions
9.
Hydrochloric acid
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Hydrochloric acid is a corrosive, strong mineral acid with many industrial uses. A colorless, highly pungent solution of chloride in water. Free hydrochloric acid was first formally described in the 16th century by Libavius, later, it was used by chemists such as Glauber, Priestley, and Davy in their scientific research. It has numerous applications, including household cleaning, production of gelatin and other food additives, descaling. About 20 million tonnes of acid are produced worldwide annually. It is also found naturally in gastric acid, Hydrochloric acid was known to European alchemists as spirits of salt or acidum salis. Both names are used, especially in other languages, such as German, Salzsäure, Dutch, Zoutzuur, Swedish, Saltsyra, Turkish, Tuz Ruhu, Polish, kwas solny and Chinese. Gaseous HCl was called marine acid air, the old name muriatic acid has the same origin, and this name is still sometimes used. The name hydrochloric acid was coined by the French chemist Joseph Louis Gay-Lussac in 1814, aqua regia, a mixture consisting of hydrochloric and nitric acids, prepared by dissolving sal ammoniac in nitric acid, was described in the works of Pseudo-Geber, a 13th-century European alchemist. Other references suggest that the first mention of aqua regia is in Byzantine manuscripts dating to the end of the 13th century, free hydrochloric acid was first formally described in the 16th century by Libavius, who prepared it by heating salt in clay crucibles. Joseph Priestley of Leeds, England prepared pure hydrogen chloride in 1772, during the Industrial Revolution in Europe, demand for alkaline substances increased. A new industrial process developed by Nicolas Leblanc of Issoundun, France enabled cheap large-scale production of sodium carbonate, in this Leblanc process, common salt is converted to soda ash, using sulfuric acid, limestone, and coal, releasing hydrogen chloride as a by-product. Until the British Alkali Act 1863 and similar legislation in other countries, after the passage of the act, soda ash producers were obliged to absorb the waste gas in water, producing hydrochloric acid on an industrial scale. In the 20th century, the Leblanc process was replaced by the Solvay process without a hydrochloric acid by-product. Since hydrochloric acid was already settled as an important chemical in numerous applications. After the year 2000, hydrochloric acid is made by absorbing by-product hydrogen chloride from industrial organic compounds production. Hydrochloric acid is the salt of hydronium ion, H3O+ and chloride and it is usually prepared by treating HCl with water. H C l + H2 O ⟶ H3 O + + C l − Hydrochloric acid can therefore be used to prepare salts called chlorides, Hydrochloric acid is a strong acid, since it is completely dissociated in water
10.
Metal halides
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Metal halides are compounds between metals and halogens. Some, such as sodium chloride are ionic, while others are covalently bonded, covalently bonded metal halides may be discrete molecules, such as uranium hexafluoride, or they may form polymeric structures, such as palladium chloride. The halogens can all react with metals to form metal halides according to the equation, 2M + nX2 → 2MXn where M is the metal, X is the halogen. In principle, most metal halides may be prepared by direct combination of the elements, for example, tin tetrachloride, Sn +2 Cl2 → SnCl4 In practice, this type of reaction may be very exothermic, hence impractical as a preparative technique. Additionally, many metals can adopt multiple oxidation states, which complicates matters. As the halogens are strong oxidizers, direct combination of the elements usually leads to an oxidized metal halide. For example, ferric chloride can be prepared thus, but ferrous chloride cannot, heating the higher halides may produce the lower halides, this occurs by thermal decomposition or by disproportionation. For example, with sodium hydroxide, NaOH + HCl → NaCl + H2O Water may be removed by heat, vacuum and this reaction is so reliable that silver nitrate is used to test for the presence and quantity of halide anions. They freely dissolve in water, and some are deliquescent and they are generally poorly soluble in organic solvents. Some low-oxidation state transition metals have halides which dissolve well in water, such as chloride, nickelous chloride. Metal cations with an oxidation state tend to undergo hydrolysis instead, e. g. ferric chloride, aluminium chloride. Discrete metal halides have lower melting and boiling points, for example, titanium tetrachloride melts at −25 °C and boils at 135 °C, making it a liquid at room temperature. They are usually insoluble in water, but soluble in organic solvent, polymeric metal halides generally have melting and boiling points that are higher than monomeric metal halides, but lower than ionic metal halides. They are soluble only in the presence of a ligand which liberates discrete units and it gives fluoroantimonic acid, the strongest known acid, with hydrogen fluoride. Antimony pentafluoride as the prototypical Lewis acid, used to different compounds Lewis basicities. This measure of basicity is known as the Gutmann donor number, halides are X-type ligands in coordination chemistry. The halides are usually good σ- and good π-donors and these ligands are usually terminal, but they might act as bridging ligands as well. Due to their π-basicity, the ligands are weak field ligands
11.
Splint (laboratory equipment)
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A splint is a simple piece of equipment used in scientific laboratories. Splints are typically long, thin strips of wood, about 6 inches long and ¼ inch wide, and are consumable but inexpensive. They are typically used for such as lighting bunsen burners, as the length of the splint allows a flame to be lit without risk to the users hand. Another use for splints are chemical identification of gases, and are also used to teach simple chemical principles in schools. Some gases are hard to distinguish by sight or smell alone, for example, hydrogen, oxygen and nitrogen are all colourless and odourless. Several laboratory experiments are capable of producing relatively pure gas as an end product, burning splints or glowing splints can be used to identify whether a gas is flammable, whether it is oxidising, or whether it is chemically inert. These tests are not safe for completely unidentified gases, as the energy of their explosion could be beyond the safe confinement of a glass tube. This means that they are only useful as a demonstration of a gas that is already strongly suspected. In a high school class, a typical use would be to show the presence of hydrogen. A burning splint can be used to test for a combustible gas, a sample of the gas is trapped in a vessel such as a boiling tube with a stopper. A splint is lit and held near the opening of the tube, if the gas is flammable, the mixture ignites. This test is most commonly used to identify hydrogen, which ignites with a distinctive squeaky pop sound, Hydrogen is easily ignited, as it is flammable over a wide range of concentrations in air, making this test quite robust. If the gas is non-flammable, the burning splint will be extinguished, as many other common gases are not flammable, this test cannot be used to definitively conclude what the gas actually is. Further analytical chemistry techniques can clarify the identity of the gas in question, the glowing splint test is a test for an oxidising gas, such as oxygen. In this test, a splint is lit, allowed to burn for a few seconds, whilst the ember at the tip is still glowing hot, the splint is introduced to the gas sample that has been trapped in a vessel. Upon exposure to concentrated oxygen gas, the glowing ember flares, the more concentrated the oxygen, the faster the wood burns, and the more intense the flame. This test is not specific for oxygen, but will react similarly for any oxidising gas that supports the combustion of the splint, flame test Testing for Hydrogen Gas on YouTube Relight of glowing splint by oxygen on YouTube Nitrous oxide and a glowing splint on YouTube
12.
Cotton swab
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Cotton swabs or cotton buds consist of a small wad of cotton wrapped around one or both ends of a short rod, usually made of either wood, rolled paper, or plastic. They are commonly used in a variety of applications including first aid, cosmetics application, cleaning, the cotton swab is a tool invented in the 1920s by Leo Gerstenzang after he attached wads of cotton to toothpicks. His product, which he named Baby Gays, went on to become the most widely sold brand name, Q-tips, the term Q-tips is often used as a genericized trademark for cotton swabs in the USA and Canada. The Q-tips brand is owned by Unilever and had over $200 million in sales in the US in 2014, although doctors have said for years that usage of the cotton swab for ear cleaning or scratching is not safe, such use remains the most common. The traditional cotton swab has a tip on a wooden handle. They are usually long, about six inches. These often are packaged sterile, one or two to a paper or plastic sleeve, the advantage of the paper sleeve and the wooden handle is that the package can be autoclaved to be sterilized. Cotton swabs manufactured for use are usually shorter, about three inches long, and usually double-tipped. The handles were first made of wood, then made of rolled paper and they are often sold in large quantities,100 or more to a container. Plastic swab stems exist in a variety of colors, such as blue. However, the cotton itself is traditionally white, the most common use for cotton swabs is to clean or caress the ear canal and/or to remove earwax, despite this not being a medically recommended method for removing earwax. Cotton swabs are commonly used for applying and removing makeup, as well as for household uses such as cleaning. Medical-type swabs are used to take microbiological cultures. They are swabbed onto or into the area, then wiped across the culture medium, such as an agar plate. They are also used to take DNA samples, most commonly by scraping cells from the cheek in the case of humans. They can be used to apply medicines to an area, to selectively remove substances from a targeted area. They are also used as an applicator for various cosmetics, ointments, a related area is the use of swabs for microbiological environmental monitoring. Once taken, the swab can be streaked onto an agar plate, the broth can either then be filtered or incubated and examined for microbial growth
13.
Melamine foam
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Melamine foam is a foam-like material consisting of a formaldehyde-melamine-sodium bisulfite copolymer. The foam is manufactured by a number of worldwide, most notably by Germany-based BASF under the name Basotect. It has been used for twenty years as insulation for pipes and ductwork, and has a long history as a soundproofing material for studios, sound stages, auditoriums. The low smoke and flame properties of melamine foam prevent it from being a fire hazard, melamine foam is the active component of a number of abrasive cleaner sponges. It is also used as the sound and thermal insulation material for bullet trains, due to its high sound absorption, excellent thermal insulation performance. Formaldehyde-melamine-bisulfite copolymers have been used for twenty years as thermal insulation for pipes. The material also has used for many years as a soundproofing material. Applications include in recording studio, sound stage, auditorium, melamine foam materials are also used in applications that combine the thermal and sound insulating properties. For instance, some trains make use of these properties and its light weight. In the early 21st century it was discovered that melamine foam is an abrasive cleaner. On a larger scale the material feels soft, because the reticulated foam bubbles interconnect, its structure is a 3D network of very hard strands, when compared to the array of separate bubbles in a material such as styrofoam. Rubbing with a slightly moistened foam may remove otherwise uncleanable external markings from surfaces, if the surface being cleaned is not sufficiently hard, it may be finely scratched by the melamine material. The foam wears away, rather like a pencil eraser, leaving behind a residue which can be rinsed off. The Material is also sold as an effective dental stain remover for private use and it is however warned to not use it on dental fillings as their surface may lose its shine
14.
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
15.
Cobalt blue glass
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Cobalt glass—known as smalt when ground as a pigment—is a deep blue colored glass prepared by including a cobalt compound, typically cobalt oxide or cobalt carbonate, in a glass melt. Cobalt is a very intense glass colorant and very little is required to show a noticeable amount of color. Cobalt blue glass is used as an optical filter in flame tests to filter out the yellow flame caused by the contamination of sodium. Cobalt glass such as Bristol blue glass is popular with collectors and it is appreciated for its attractive color. Cobalt aluminate, also known as blue, can be used in a similar way. The earliest known example of cobalt aluminate glass dates to a lump from about 2000BC in ancient Mesopotamia, very possibly intended for use as a pigment, it is then rare until the modern era. About five centuries later cobalt oxide smalt appears as a pigment in Egyptian pottery, and soon after in the Aegean region, in paintings, smalt has a tendency to lose its colour over a long period and is little used today. Chinese porcelain used smalt glazes from the Tang Dynasty onwards, though Chinese cobalt glass is found from the Zhou dynasty, Cobalt was used as a pigment in Central Asia from the 13th century. A fragment of a mud painting in the ancient Tangut city of Khara-Khoto has been found to contain smalt, a large quantity of smalt was purchased for the decoration of the gallery of Francis I of France at Fontainebleau in 1536. Smalt, normally now discoloured, is common in European paintings from the 15th to 17th centuries, for example, it was found in Hans Holbein the Youngers portrait of Sir William Butts, in Michael Pachers painting The Early Fathers Altar, and in the frescos of Domenico Ghirlandaio. The invention of a European smalt process has traditionally been credited to a Bohemian glassmaker named Christoph Schürer, however, its presence in Dieric Bouts The Entombment from circa 1455 proves that it was used at least a century earlier. The result was an intensive blue glass-like substance that was ground and sold to producers of glassware, Cobalt blue Cobalt Smalt, Bruno Mühlethaler and Jean Thissen, Studies in Conservation, Vol.14, No. 2, pp. 47–61, JSTOR Smalt Pigments through the Ages Bromo-Seltzer, Cobalt Blue bottles - Brief Summary M-inside-a-circle, Maryland Glass Corporation, Baltimore
16.
Photoelectric flame photometer
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A photoelectric flame photometer is a device used in inorganic chemical analysis to determine the concentration of certain metal ions, among them sodium, potassium, lithium, and calcium. Group 1 and Group 2 metals are quite sensitive to Flame Photometry due to their low excitation energies, in principle, it is a controlled flame test with the intensity of the flame colour quantified by photoelectric circuitry. The intensity of the colour depend on the energy that had been absorbed by the atoms that was sufficient to vaporise them. The sample is introduced to the flame at a constant rate, filters select which colours the photometer detects and exclude the influence of other ions. Before use, the device requires calibration with a series of solutions of the ion to be tested. Flame photometry is crude but cheap compared to flame emission spectroscopy and its status is similar to that of the colorimeter compared to the spectrophotometer. It also has the range of metals that could be analysed and the limit of detection are also considered
17.
Atomic absorption spectroscopy
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Atomic absorption spectroscopy is a spectroanalytical procedure for the quantitative determination of chemical elements using the absorption of optical radiation by free atoms in the gaseous state. In analytical chemistry the technique is used for determining the concentration of an element in a sample to be analyzed. AAS can be used to determine over 70 different elements in solution or directly in solid samples used in pharmacology, biophysics, the modern form of AAS was largely developed during the 1950s by a team of Australian chemists. They were led by Sir Alan Walsh at the Commonwealth Scientific and Industrial Research Organisation, Division of Chemical Physics, in Melbourne, the technique makes use of absorption spectrometry to assess the concentration of an analyte in a sample. It requires standards with known content to establish the relation between the measured absorbance and the analyte concentration and relies therefore on the Beer-Lambert Law. In short, the electrons of the atoms in the atomizer can be promoted to higher orbitals for a period of time by absorbing a defined quantity of energy. This amount of energy, i. e. wavelength, is specific to an electron transition in a particular element. In general, each corresponds to only one element, and the width of an absorption line is only of the order of a few picometers. In order to analyze a sample for its constituents, it has to be atomized. The atomizers most commonly used nowadays are flames and electrothermal atomizers, the atoms should then be irradiated by optical radiation, and the radiation source could be an element-specific line radiation source or a continuum radiation source. The atomizers most commonly used nowadays are flames and electrothermal atomizers, other atomizers, such as glow-discharge atomization, hydride atomization, or cold-vapor atomization might be used for special purposes. The latter flame, in addition, offers a more reducing environment, liquid or dissolved samples are typically used with flame atomizers. This conditioning process is responsible that only about 5% of the sample solution reaches the flame. On top of the chamber is a burner head that produces a flame that is laterally long. The radiation beam passes through this flame at its longest axis, the burner height may also be adjusted, so that the radiation beam passes through the zone of highest atom cloud density in the flame, resulting in the highest sensitivity. Each of these includes the risk of interference in case the degree of phase transfer is different for the analyte in the calibration standard. Ionization is generally undesirable, as it reduces the number of atoms that are available for measurement, in flame AAS a steady-state signal is generated during the time period when the sample is aspirated. This technique is used for determinations in the mg L−1 range
18.
Aluminium
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Aluminium or aluminum is a chemical element in the boron group with symbol Al and atomic number 13. It is a silvery-white, soft, nonmagnetic, ductile metal, Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is combined in over 270 different minerals. The chief ore of aluminium is bauxite, Aluminium is remarkable for the metals low density and its ability to resist corrosion through the phenomenon of passivation. Aluminium and its alloys are vital to the industry and important in transportation and structures, such as building facades. The oxides and sulfates are the most useful compounds of aluminium, despite its prevalence in the environment, no known form of life uses aluminium salts metabolically, but aluminium is well tolerated by plants and animals. Because of these salts abundance, the potential for a role for them is of continuing interest. Aluminium is a soft, durable, lightweight, ductile. It is nonmagnetic and does not easily ignite, a fresh film of aluminium serves as a good reflector of visible light and an excellent reflector of medium and far infrared radiation. The yield strength of aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium has about one-third the density and stiffness of steel and it is easily machined, cast, drawn and extruded. Aluminium atoms are arranged in a cubic structure. Aluminium has an energy of approximately 200 mJ/m2. Aluminium is a thermal and electrical conductor, having 59% the conductivity of copper. Aluminium is capable of superconductivity, with a critical temperature of 1.2 kelvin. Aluminium is the most common material for the fabrication of superconducting qubits, the strongest aluminium alloys are less corrosion resistant due to galvanic reactions with alloyed copper. This corrosion resistance is reduced by aqueous salts, particularly in the presence of dissimilar metals. In highly acidic solutions, aluminium reacts with water to form hydrogen, primarily because it is corroded by dissolved chlorides, such as common sodium chloride, household plumbing is never made from aluminium
19.
Silver (color)
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Silver or metallic gray is a color tone resembling gray that is a representation of the color of polished silver. The visual sensation usually associated with the silver is its metallic shine. This cannot be reproduced by a solid color, because the shiny effect is due to the materials brightness varying with the surface angle to the light source. In addition, there is no mechanism for showing metallic or fluorescent colors on a computer without resorting to rendering software which simulates the action of light on a shiny surface, consequently, in art and in heraldry one would normally use a metallic paint that glitters like real silver. A matte grey color could also be used to represent silver color, the first recorded use of silver as a color name in English was in 1481. In heraldry, the word argent is used, derived from Latin argentum over Medieval French argent, displayed at right is the web color silver. Since version 3.2 of HTML silver is a name for one of the 16 basic-VGA-colors, hTML-example, <body bgcolor=silver> CSS-example, body Pale silver is the pale tone of silver color called silver in Crayola crayons. Silver has been a Crayola color since 1903, Crayola silver is not a neutral grayscale color, but rather a warm gray with a very slight tinge of orange-red. The color silver pink is displayed at right, the color name silver pink first came into use in 1948. The source of color is the Plochere Color System, a color system formulated in 1948 that is widely used by interior designers. At right is displayed the color silver sand, the color name silver sand for this tone of silver has been in use since 2001, when it was promulgated as one of the colors on the Xona. com Color List. At right is displayed the color silver chalice, the color name silver chalice for this tone of silver has been in use since 2001, when it was promulgated as one of the colors on the Xona. com Color List. At right is displayed the color Roman silver, Roman silver, a blue-gray tone of silver, is one of the colors on the Resene Color List, a color list widely popular in Australia and New Zealand. At right is displayed the old silver. Old silver is a color that was formulated to resemble tarnished silver, the first recorded use of old silver as a color name in English was in 1905. Sonic silver is a tone of silver included in Metallic FX crayons, plants A silver birch is a tree in the birch family. The leaves are silver on underside. A silver fir is a timber tree that originated in Europe
20.
Arsenic
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Arsenic is a chemical element with symbol As and atomic number 33. Arsenic occurs in minerals, usually in combination with sulfur and metals. It has various allotropes, but only the form is important to industry. The primary use of arsenic is in alloys of lead. Arsenic is a common dopant in semiconductor electronic devices. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, a few species of bacteria are able to use arsenic compounds as respiratory metabolites. Trace quantities of arsenic are a dietary element in rats, hamsters, goats, chickens. However, arsenic poisoning occurs in multicellular life if quantities are larger than needed, Arsenic contamination of groundwater is a problem that affects millions of people across the world. The three most common allotropes are metallic gray, yellow, and black arsenic, with gray being the most common. Gray arsenic adopts a structure consisting of many interlocked, ruffled, six-membered rings. Because of weak bonding between the layers, gray arsenic is brittle and has a relatively low Mohs hardness of 3.5. Nearest and next-nearest neighbors form an octahedral complex, with the three atoms in the same double-layer being slightly closer than the three atoms in the next. This relatively close packing leads to a density of 5.73 g/cm3. Gray arsenic is a semimetal, but becomes a semiconductor with a bandgap of 1. 2–1.4 eV if amorphized, gray arsenic is also the most stable form. Yellow arsenic is soft and waxy, and somewhat similar to tetraphosphorus, both have four atoms arranged in a tetrahedral structure in which each atom is bound to each of the other three atoms by a single bond. This unstable allotrope, being molecular, is the most volatile, least dense, solid yellow arsenic is produced by rapid cooling of arsenic vapor, As 4. It is rapidly transformed into gray arsenic by light, the yellow form has a density of 1.97 g/cm3. Black arsenic is similar in structure to red phosphorus, black arsenic can also be formed by cooling vapor at around 100–220 °C
21.
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
22.
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
23.
Beryllium
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Beryllium is a chemical element with symbol Be and atomic number 4. It is a rare element in the universe, usually occurring as a product of the spallation of larger atomic nuclei that have collided with cosmic rays. Within the cores of stars beryllium is depleted as it is fused and it is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl and chrysoberyl, as a free element it is a steel-gray, strong, lightweight and brittle alkaline earth metal. Beryllium improves many physical properties when added as an element to aluminium, copper, iron. Beryllium does not form oxides until it reaches high temperatures. Tools made of copper alloys are strong and hard and do not create sparks when they strike a steel surface. The high thermal conductivities of beryllium and beryllium oxide have led to their use in thermal management applications, Beryllium is a steel gray and hard metalloid that is brittle at room temperature and has a close-packed hexagonal crystal structure. It has exceptional stiffness and a high melting point. The modulus of elasticity of beryllium is approximately 50% greater than that of steel, the combination of this modulus and a relatively low density results in an unusually fast sound conduction speed in beryllium – about 12.9 km/s at ambient conditions. Other significant properties are high specific heat and thermal conductivity, which make beryllium the metal with the best heat dissipation characteristics per unit weight, in combination with the relatively low coefficient of linear thermal expansion, these characteristics result in a unique stability under conditions of thermal loading. Naturally occurring beryllium, save for slight contamination by cosmogenic radioisotopes, is essentially pure beryllium-9, Beryllium has a large scattering cross section for high-energy neutrons, about 6 barns for energies above approximately 10 keV. The single primordial beryllium isotope 9Be also undergoes a neutron reaction with neutron energies over about 1.9 MeV, to produce 8Be, thus, for high-energy neutrons, beryllium is a neutron multiplier, releasing more neutrons than it absorbs. Beryllium also releases neutrons under bombardment by gamma rays.8 seconds, β− is an electron, tritium is a radioisotope of concern in nuclear reactor waste streams. As a metal, beryllium is transparent to most wavelengths of X-rays and gamma rays, making it useful for the windows of X-ray tubes. Both stable and unstable isotopes of beryllium are created in stars, primordial beryllium contains only one stable isotope, 9Be, and therefore beryllium is a monoisotopic element. Radioactive cosmogenic 10Be is produced in the atmosphere of the Earth by the cosmic ray spallation of oxygen, 10Be accumulates at the soil surface, where its relatively long half-life permits a long residence time before decaying to boron-10. The production of 10Be is inversely proportional to activity, because increased solar wind during periods of high solar activity decreases the flux of galactic cosmic rays that reach the Earth
24.
Bismuth
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Bismuth is a chemical element with the symbol Bi and atomic number 83. Bismuth, a pentavalent post-transition metal and one of the pnictogens, chemically resembles its lighter homologs arsenic, elemental bismuth may occur naturally, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead and it is a brittle metal with a silvery white color when freshly produced, but surface oxidation can give it a pink tinge. Bismuth is the most naturally diamagnetic element, and has one of the lowest values of thermal conductivity among metals, Bismuth metal has been known since ancient times, although it was often confused with lead and tin, which share some physical properties. Bismuth was long considered the element with the highest atomic mass that is stable, because of its tremendously long half-life, bismuth may still be considered stable for almost all purposes. Bismuth compounds account for half the production of bismuth. They are used in cosmetics, pigments, and a few pharmaceuticals, notably bismuth subsalicylate, bismuths unusual propensity to expand upon freezing is responsible for some of its uses, such as in casting of printing type. Bismuth has unusually low toxicity for a heavy metal, as the toxicity of lead has become more apparent in recent years, there is an increasing use of bismuth alloys as a replacement for lead. The name bismuth dates from around the 1660s, and is of uncertain etymology and it is one of the first 10 metals to have been discovered. Bismuth appears in the 1660s, from obsolete German Bismuth, Wismut, Wissmuth, the New Latin bisemutum is from the German Wismuth, perhaps from weiße Masse, white mass. The element was confused in early times with tin and lead because of its resemblance to those elements, Bismuth has been known since ancient times, so no one person is credited with its discovery. Agricola, in De Natura Fossilium states that bismuth is a metal in a family of metals including tin. This was based on observation of the metals and their physical properties, miners in the age of alchemy also gave bismuth the name tectum argenti, or silver being made, in the sense of silver still in the process of being formed within the Earth. Bismuth was also known to the Incas and used in a bronze alloy for knives. Bismuth is a metal with a white, silver-pink hue, often occurring in its native form. The spiral, stair-stepped structure of crystals is the result of a higher growth rate around the outside edges than on the inside edges. The variations in the thickness of the layer that forms on the surface of the crystal causes different wavelengths of light to interfere upon reflection. When burned in oxygen, bismuth burns with a blue flame and its toxicity is much lower than that of its neighbors in the periodic table, such as lead, antimony, and polonium
25.
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
26.
Cadmium
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Cadmium is a chemical element with symbol Cd and atomic number 48. This soft, bluish-white metal is similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of its compounds, Cadmium and its congeners are not always considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. The average concentration of cadmium in Earths crust is between 0.1 and 0.5 parts per million and it was discovered in 1817 simultaneously by Stromeyer and Hermann, both in Germany, as an impurity in zinc carbonate. Cadmium occurs as a component in most zinc ores and is a byproduct of zinc production. Cadmium was used for a time as a corrosion-resistant plating on steel, and cadmium compounds are used as red, orange and yellow pigments, to colour glass. Cadmium use is decreasing because it is toxic and nickel-cadmium batteries have been replaced with nickel-metal hydride. One of its few new uses is cadmium telluride solar panels, although cadmium has no known biological function in higher organisms, a cadmium-dependent carbonic anhydrase has been found in marine diatoms. Cadmium is a soft, malleable, ductile, bluish-white divalent metal and it is similar in many respects to zinc but forms complex compounds. Unlike most other metals, cadmium is resistant to corrosion and is used as a plate on other metals. As a bulk metal, cadmium is insoluble in water and is not flammable, however, in its form it may burn. Although cadmium usually has a state of +2, it also exists in the +1 state. Cadmium and its congeners are not always considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. Cadmium burns in air to form brown amorphous cadmium oxide, the form of this compound is a dark red which changes color when heated. Hydrochloric acid, sulfuric acid, and nitric acid dissolve cadmium by forming cadmium chloride, cadmium sulfate, Cd + CdCl2 +2 AlCl3 → Cd22 The structures of many cadmium complexes with nucleobases, amino acids, and vitamins have been determined. Naturally occurring cadmium is composed of 8 isotopes, two of them are radioactive, and three are expected to decay but have not done so under laboratory conditions. The two natural isotopes are 113Cd and 116Cd. The other three are 106Cd, 108Cd, and 114Cd, only lower limits on these half-lives have been determined, at least three isotopes – 110Cd, 111Cd, and 112Cd – are stable
27.
Cerium
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Cerium is a soft, ductile, silvery-white metallic chemical element with symbol Ce and atomic number 58. Cerium tarnishes when exposed to air, and it is enough to be cut with a knife. Cerium is the element in the lanthanide series, and while it often shows the +3 state characteristic of the series. It is also considered to be one of the rare earth elements. Cerium has no role, and is not very toxic. It is the most common of the lanthanides, followed by neodymium, lanthanum and it is the 26th most abundant element, making up 66 ppm of the Earths crust, half as much as chlorine and five times as much as lead. The first of the lanthanides to be discovered, cerium was discovered in Bastnäs, Sweden by Jöns Jakob Berzelius and Wilhelm Hisinger in 1803 and it was first isolated by Carl Gustaf Mosander in 1839. Today, cerium and its compounds have a variety of uses, for example, cerium metal is used in ferrocerium lighters for its pyrophoric properties. Cerium is the element of the lanthanide series. In the periodic table, it appears between the lanthanides lanthanum to its left and praseodymium to its right, and above the actinide thorium and it is a ductile metal with a hardness similar to that of silver. Its 58 electrons are arranged in the configuration 4f15d16s2, of which the four electrons are valence electrons. The stable form below 726 °C to approximately room temperature is γ-cerium, the dhcp form of β-cerium is the equilibrium structure approximately from room temperature to −150 °C. The fcc α-cerium exists below about −150 °C, it has a density of 8.16 g/cm3, other solid phases occurring only at high pressures are shown on the phase diagram. Both γ and β forms are stable at room temperature. Cerium has an electronic structure. This gives rise to dual valency states, for example, a volume change of about 10% occurs when cerium is subjected to high pressures or low temperatures. It appears that the changes from about 3 to 4 when it is cooled or compressed. At lower temperatures the behavior of cerium is complicated by the rates of transformation
28.
Cobalt
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Cobalt is a chemical element with symbol Co and atomic number 27. Like nickel, cobalt is found in the Earths crust only in chemically combined form, the free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal. In 1735, such ores were found to be reducible to a new metal, today, some cobalt is produced specifically from various metallic-lustered ores, for example cobaltite, but the main source of the element is as a by-product of copper and nickel mining. The copper belt in the Democratic Republic of the Congo, Central African Republic, cobalt is primarily used in the preparation of magnetic, wear-resistant and high-strength alloys. The compounds, cobalt silicate and cobalt aluminate give a deep blue color to glass, ceramics, inks, paints. Cobalt occurs naturally as only one isotope, cobalt-59. Cobalt-60 is an important radioisotope, used as a radioactive tracer. Cobalt is the center of coenzymes called cobalamins, the most common example of which is vitamin B12. As such, it is a trace dietary mineral for all animals. Cobalt in inorganic form is also a micronutrient for bacteria, algae, cobalt is a ferromagnetic metal with a specific gravity of 8.9. The Curie temperature is 1,115 °C and the moment is 1. 6–1.7 Bohr magnetons per atom. Cobalt has a relative permeability two-thirds that of iron, metallic cobalt occurs as two crystallographic structures, hcp and fcc. The ideal transition temperature between the hcp and fcc structures is 450 °C, but in practice, the difference is so small that random intergrowth of the two is common. Cobalt is a weakly reducing metal that is protected from oxidation by an oxide film. It is attacked by halogens and sulfur, heating in oxygen produces Co3O4 which loses oxygen at 900 °C to give the monoxide CoO. The metal reacts with fluorine at 520 K to give CoF3, with chlorine, bromine and iodine and it does not react with hydrogen gas or nitrogen gas even when heated, but it does react with boron, carbon, phosphorus, arsenic and sulfur. At ordinary temperatures, it reacts slowly with mineral acids, and very slowly with moist, common oxidation states of cobalt include +2 and +3, although compounds with oxidation states ranging from −3 to +5 are also known. A common oxidation state for simple compounds is +2 and these salts form the pink-colored metal aquo complex 2+ in water
29.
Chromium
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Chromium is a chemical element with symbol Cr and atomic number 24. It is the first element in Group 6 and it is a steely-grey, lustrous, hard and brittle metal which takes a high polish, resists tarnishing, and has a high melting point. The name of the element is derived from the Greek word χρῶμα, chrōma, meaning color, Chromium metal is of high value for its high corrosion resistance and hardness. A major development was the discovery that steel could be highly resistant to corrosion and discoloration by adding metallic chromium to form stainless steel. Stainless steel and chrome plating together comprise 85% of the commercial use, trivalent chromium ion is an essential nutrient in trace amounts in humans for insulin, sugar and lipid metabolism, although the issue is debated. While chromium metal and Cr ions are not considered toxic, hexavalent chromium is toxic and carcinogenic, abandoned chromium production sites often require environmental cleanup. Chromium is remarkable for its properties, it is the only elemental solid which shows antiferromagnetic ordering at room temperature. Above 38 °C, it changes to paramagnetic, Chromium metal left standing in air is passivated by oxidation, forming a thin, protective, surface layer. This layer is a structure only a few molecules thick. It is very dense, and prevents the diffusion of oxygen into the underlying metal and this is different from the oxide that forms on iron and carbon steel, through which elemental oxygen continues to migrate, reaching the underlying material to cause incessant rusting. Passivation can be enhanced by short contact with oxidizing acids like nitric acid, passivated chromium is stable against acids. Passivation can be removed with a reducing agent that destroys the protective oxide layer on the metal. Chromium metal treated in this way readily dissolves in weak acids, Chromium, unlike such metals as iron and nickel, does not suffer from hydrogen embrittlement. However, it suffer from nitrogen embrittlement, reacting with nitrogen from air. Chromium is the 22nd most abundant element in Earths crust with a concentration of 100 ppm. Chromium compounds are found in the environment from the erosion of chromium-containing rocks, Chromium is mined as chromite ore. About two-fifths of the ores and concentrates in the world are produced in South Africa, while Kazakhstan, India, Russia. Untapped chromite deposits are plentiful, but geographically concentrated in Kazakhstan, although rare, deposits of native chromium exist
30.
Caesium
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Caesium or cesium is a chemical element with symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a point of 28.5 °C. Caesium is a metal and has physical and chemical properties similar to those of rubidium and potassium. The metal is extremely reactive and pyrophoric, reacting with water even at −116 °C, Caesium is one of the most reactive elements of all, even more reactive than fluorine, the most reactive nonmetal. It is the least electronegative element, with a value of 0.79 on the Pauling scale and it has only one stable isotope, caesium-133. Caesium is mined mostly from pollucite, while the radioisotopes, especially caesium-137, the German chemist Robert Bunsen and physicist Gustav Kirchhoff discovered caesium in 1860 by the newly developed method of flame spectroscopy. The first small-scale applications for caesium were as a getter in vacuum tubes, since then, caesium has been widely used in highly accurate atomic clocks. The radioactive isotope caesium-137 has a half-life of about 30 years and is used in applications, industrial gauges. Although the element is only toxic, the metal is a hazardous material. It is a ductile, pale metal, which darkens in the presence of trace amounts of oxygen. When in the presence of oil, it loses its metallic lustre and takes on a duller. It has a point of 28.4 °C, making it one of the few elemental metals that are liquid near room temperature. Mercury is the elemental metal with a known melting point lower than caesium. In addition, the metal has a low boiling point,641 °C. Its compounds burn with a blue or violet colour, Caesium forms alloys with the other alkali metals, gold, and mercury. At temperatures below 650 °C, it does not alloy with cobalt, iron, molybdenum, nickel, platinum, tantalum and it forms well-defined intermetallic compounds with antimony, gallium, indium, and thorium, which are photosensitive. It mixes with all the alkali metals, the alloy with a molar distribution of 41% caesium, 47% potassium. A few amalgams have been studied, CsHg 2 is black with a metallic lustre, while CsHg is golden-coloured
31.
Violet (color)
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Violet is the color of amethyst, lavender and beautyberries. It takes its name from the violet flower, Violet is the color at the end of the visible spectrum of light between blue and the invisible ultraviolet. Violet color has a predominant light wavelength of roughly 380-450 nanometers, light with a shorter wavelength than violet but longer than X-rays and gamma rays is called ultraviolet. In the color wheel used by painters, it is located between blue and purple. This is not true violet, since it is composed of multiple longer wavelengths rather than a wavelength shorter than that of blue light. Violet and purple look very similar, but violet is a color, with its own set of wavelengths on the spectrum of visible light, while purple is a composite color, made by combining blue. In history, violet and purple have long associated with royalty and majesty. The emperors of Rome wore purple togas, as did the Byzantine emperors, during the Middle Ages violet was worn by bishops and university professors and was often used in art as the color of the robes of the Virgin Mary. According to surveys in Europe and the United States, violet is the people most often associate with extravagance and individualism, the unconventional, the artificial. In Chinese painting, the color represents the harmony of the universe because it is a combination of red. In Hinduism and Buddhism violet is associated with the Crown Chakra, from the Middle English and old French violette, and from the Latin viola, the names of the violet flower. The first recorded use of violet as a name in English was in 1370. Violet can also refer to the first violas which were painted a similar color. In the traditional color used by painters, violet and purple are both placed between red and blue. Purple occupies the space closer to red, between crimson and violet, Violet is closer to blue, and usually less intense and bright than purple. The range of purples is created by combining blue and red light of any intensities, Violet is one of the oldest colors used by man. It has also found in the cave of Altamira and Lascaux. It was sometimes used an alternative to black charcoal, sticks of manganese, used for drawing, have been found at sites occupied by Neanderthal man in France and Israel
32.
Blue-green
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Blue-green is a color that is a representation of the color that is between blue and green on a typical traditional old-fashioned RYB color wheel. Blue-green belongs to the family of colors. The source of color is the List of Crayola crayon colors. Blue-green has been a Crayola crayon color since 1930, cyan, also called aqua, is the blue-green color that is between blue and green on a modern RGB color wheel. In the terminology of color theory, RGB color space has a larger color gamut than RYB color space. The first recorded use of cyan as a name in English was in 1879. At right is displayed the color turquoise, a representation of the color of the stone turquoise. The first recorded use of turquoise as a name in English was in 1573. The color turquoise is a tone of blue-green. Displayed at right is the color Ming This color was formulated in 2001 as one of the colors on the Xona. com Color List, displayed at right is the color Pacific blue. Pacific blue was formulated as a Crayola color in 1993, the color is a representation of the waters of the Pacific. Bondi blue is a color belonging to the family of blues. It is very similar to the Crayola crayon color blue-green, apple christened the color of the exterior of its original iMac G3 personal computer Bondi blue when it was introduced in 1998. The color is said to be named for the color of the water at Bondi Beach in Sydney, green-blue had been a Crayola color since 1958. It was continued as a Crayola crayon color until 1990, cerulean is a medium blue-green color that is used to represent or symbolize either the sky or the ocean. The first recorded use of cerulean as a name in English was in 1590. Teal is a medium blue-green color and it is named after the common teal, a member of the duck family, whose eyes are surrounded by the color. The color teal has a hue that is halfway between blue and green and a value that is exactly halfway between white and black
33.
Germanium
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Germanium is a chemical element with symbol Ge and atomic number 32. It is a lustrous, hard, grayish-white metalloid in the group, chemically similar to its group neighbors tin. Pure germanium is a semiconductor with a similar to elemental silicon. Like silicon, germanium naturally reacts and forms complexes with oxygen in nature, unlike silicon, it is too reactive to be found naturally on Earth in the free state. Because it seldom appears in high concentration, germanium was discovered late in the history of chemistry. Germanium ranks near fiftieth in relative abundance of the elements in the Earths crust, in 1869, Dmitri Mendeleev predicted its existence and some of its properties from its position on his periodic table, and called the element ekasilicon. Nearly two decades later, in 1886, Clemens Winkler found the new element along with silver and sulfur, although the new element somewhat resembled arsenic and antimony in appearance, the combining ratios in compounds agreed with Mendeleevs predictions for a relative of silicon. Winkler named the element after his country, Germany, today, germanium is mined primarily from sphalerite, though germanium is also recovered commercially from silver, lead, and copper ores. Germanium metal is used as a semiconductor in transistors and various electronic devices. Historically, the first decade of semiconductor electronics was based entirely on germanium, today, the amount of germanium produced for semiconductor electronics is one fiftieth the amount of ultra-high purity silicon produced for the same. Presently, the end uses are fibre-optic systems, infrared optics, solar cell applications. Germanium compounds are used for polymerization catalysts and have most recently found use in the production of nanowires. This element forms a number of organometallic compounds, such as tetraethylgermane. Germanium is not thought to be an element for any living organism. Some complex organic compounds are being investigated as possible pharmaceuticals. Similar to silicon and aluminum, natural germanium compounds tend to be insoluble in water, however, synthetic soluble germanium salts are nephrotoxic, and synthetic chemically reactive germanium compounds with halogens and hydrogen are irritants and toxins. Because of its position in his Periodic Table, Mendeleev called it ekasilicon, in mid-1885, at a mine near Freiberg, Saxony, a new mineral was discovered and named argyrodite because of the high silver content. The chemist Clemens Winkler analyzed this new mineral, which proved to be a combination of silver, sulfur, Winkler was able to isolate the new element in 1886 and found it similar to antimony
34.
Iron
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Iron is a chemical element with symbol Fe and atomic number 26. It is a metal in the first transition series and it is by mass the most common element on Earth, forming much of Earths outer and inner core. It is the fourth most common element in the Earths crust, like the other group 8 elements, ruthenium and osmium, iron exists in a wide range of oxidation states, −2 to +6, although +2 and +3 are the most common. Elemental iron occurs in meteoroids and other low oxygen environments, but is reactive to oxygen, fresh iron surfaces appear lustrous silvery-gray, but oxidize in normal air to give hydrated iron oxides, commonly known as rust. Unlike the metals that form passivating oxide layers, iron oxides occupy more volume than the metal and thus flake off, Iron metal has been used since ancient times, although copper alloys, which have lower melting temperatures, were used even earlier in human history. Pure iron is soft, but is unobtainable by smelting because it is significantly hardened and strengthened by impurities, in particular carbon. A certain proportion of carbon steel, which may be up to 1000 times harder than pure iron. Crude iron metal is produced in blast furnaces, where ore is reduced by coke to pig iron, further refinement with oxygen reduces the carbon content to the correct proportion to make steel. Steels and iron alloys formed with metals are by far the most common industrial metals because they have a great range of desirable properties. Iron chemical compounds have many uses, Iron oxide mixed with aluminium powder can be ignited to create a thermite reaction, used in welding and purifying ores. Iron forms binary compounds with the halogens and the chalcogens, among its organometallic compounds is ferrocene, the first sandwich compound discovered. Iron plays an important role in biology, forming complexes with oxygen in hemoglobin and myoglobin. Iron is also the metal at the site of many important redox enzymes dealing with cellular respiration and oxidation and reduction in plants. A human male of average height has about 4 grams of iron in his body and this iron is distributed throughout the body in hemoglobin, tissues, muscles, bone marrow, blood proteins, enzymes, ferritin, hemosiderin, and transport in plasma. The mechanical properties of iron and its alloys can be evaluated using a variety of tests, including the Brinell test, Rockwell test, the data on iron is so consistent that it is often used to calibrate measurements or to compare tests. An increase in the content will cause a significant increase in the hardness. Maximum hardness of 65 Rc is achieved with a 0. 6% carbon content, because of the softness of iron, it is much easier to work with than its heavier congeners ruthenium and osmium. Because of its significance for planetary cores, the properties of iron at high pressures and temperatures have also been studied extensively
35.
Gold (color)
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Gold, also called golden, is one of a variety of yellow-orange color blends used to give the impression of the color of the element gold. The web color gold is sometimes referred to as golden to distinguish it from the metallic gold. The use of gold as a term in traditional usage is more often applied to the color metallic gold. The first recorded use of golden as a name in English was in 1300 to refer to the element gold. Metallic gold, such as in paint, is often called goldtone or gold-tone, in heraldry, the French word or is used. In model building, the gold is different from brass. A shiny or metallic silvertone object can be painted with transparent yellow to obtain goldtone, at right is displayed a representation of the color metallic gold which is a simulation of the color of the actual metallic element gold itself—gold shade. The American Heritage Dictionary defines the color metallic gold as A light olive-brown to dark yellow, or a moderate, of course, the visual sensation usually associated with the metal gold is its metallic shine. This cannot be reproduced by a solid color, because the shiny effect is due to the materials reflective brightness varying with the surfaces angle to the light source. Especially in sacral art in Christian churches, real gold was used for rendering gold in paintings, Gold can also be woven into sheets of silk to give an East Asian traditional look. Old gold is a yellow, which varies from heavy olive or olive brown to deep or strong yellow. The widely accepted color old gold is on the rather than the lighter side of this range. The first recorded use of old gold as a name in English was in the early 19th century. The Delta Sigma Pi fraternity, founded in November 7,1907, official colors are designated royal purple, the Pi Kappa Alpha fraternitys colors are garnet and old gold. Old gold is one of two colors of Alpha Phi Alpha fraternity, maroon and old gold are the colors of Texas State Universitys intercollegiate sports teams. Old Gold and black are the colors of Purdue University Boilermakers intercollegiate sports teams. The Georgia Tech Yellow Jackets wear white and old gold, the Wake Forest Demon Deacons, UCF Knights, and Vanderbilt Commodores wear old gold and black. The New Orleans Saints list their official team colors as black, old gold, Golden yellow is the color halfway between amber and yellow on the RGB color wheel
36.
Blue
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Blue is the colour between violet and green on the optical spectrum of visible light. Human eyes perceive blue when observing light with a wavelength between 450 and 495 nanometres, which is between 4500 and 4950 ångströms. Blues with a frequency and thus a shorter wavelength gradually look more violet, while those with a lower frequency. Pure blue, in the middle, has a wavelength of 470 nanometers, in painting and traditional colour theory, blue is one of the three primary colours of pigments, along with red and yellow, which can be mixed to form a wide gamut of colours. Red and blue mixed together form violet, blue and yellow together form green, Blue is also a primary colour in the RGB colour model, used to create all the colours on the screen of a television or computer monitor. The clear sky and the sea appear blue because of an optical effect known as Rayleigh scattering. When sunlight passes through the atmosphere, the wavelengths are scattered more widely by the oxygen and nitrogen molecules. An optical effect called Tyndall scattering, similar to Rayleigh scattering, explains blue eyes, distant objects appear more blue because of another optical effect called atmospheric perspective. Blue has been used for art and decoration since ancient times and it is the most important color in Judaism. In the Middle Ages, cobalt blue was used to colour the stained glass windows of cathedrals, beginning in the 9th century, Chinese artists used cobalt to make fine blue and white porcelain. Blue dyes for clothing were made from woad in Europe and indigo in Asia, in 1828 a synthetic ultramarine pigment was developed, and synthetic blue dyes and pigments gradually replaced mineral pigments and vegetable dyes. Pierre-Auguste Renoir, Vincent van Gogh and other late 19th century painters used ultramarine and cobalt blue not just to depict nature, in the late 18th century and 19th century, blue became a popular colour for military uniforms and police uniforms. In the 20th century, because blue was associated with harmony, it was chosen as the colour of the flags of the United Nations. Surveys in the US and Europe show that blue is the colour most commonly associated with harmony, faithfulness, confidence, distance, infinity, the imagination, cold, and sometimes with sadness. In US and European public opinion polls it is the most popular colour, Blue is the colour of light between violet and green on the visible spectrum. Blues also vary in shade or tint, darker shades of blue contain black or grey, darker shades of blue include ultramarine, cobalt blue, navy blue, and Prussian blue, while lighter tints include sky blue, azure, and Egyptian blue. Today most blue pigments and dyes are made by a chemical process, the modern English word blue comes from Middle English bleu or blewe, from the Old French bleu, a word of Germanic origin, related to the Old High German word blao. In heraldry, the azure is used for blue
37.
Hafnium
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Hafnium is a chemical element with symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals and its existence was predicted by Dmitri Mendeleev in 1869, though it was not identified until 1923, making it the penultimate stable element to be discovered. Hafnium is named after Hafnia, the Latin name for Copenhagen, Hafnium is used in filaments and electrodes. Some semiconductor fabrication processes use its oxide for integrated circuits at 45 nm, some superalloys used for special applications contain hafnium in combination with niobium, titanium, or tungsten. Hafnium is a shiny, silvery, ductile metal that is corrosion-resistant, a notable physical difference between these metals is their density, with zirconium having about one-half the density of hafnium. The most notable properties of hafnium are its high thermal neutron-capture cross-section. Hafnium reacts in air to form a film that inhibits further corrosion. The metal is not readily attacked by acids but can be oxidized with halogens or it can be burnt in air, like its sister metal zirconium, finely divided hafnium can ignite spontaneously in air, producing an effect similar to that obtained in Dragons Breath. The metal is resistant to concentrated alkalis, the chemistry of hafnium and zirconium is so similar that the two cannot be separated on the basis of differing chemical reactions. The melting points and boiling points of the compounds and the solubility in solvents are the differences in the chemistry of these twin elements. At least 34 isotopes of hafnium have been observed, ranging in number from 153 to 186. The five stable isotopes are in the range of 176 to 180, the radioactive isotopes half-lives range from only 400 ms for 153Hf, to 2.0 petayears for the most stable one, 174Hf. The nuclear isomer 178m2Hf was at the center of a controversy for several years regarding its use as a weapon. Hafnium is estimated to make up about 5.8 ppm of the Earths upper crust by mass, rarely, the Hf/Zr ratio increases during crystallization to give the isostructural mineral hafnon SiO4, with atomic Hf > Zr. An old name for a variety of zircon containing unusually high Hf content is alvite, a potential source of hafnium is trachyte tuffs containing rare zircon-hafnium silicates eudialyte or armstrongite, at Dubbo in New South Wales, Australia. Hafnium reserves have been estimated to last under 10 years by one source if the world population increases. In reality, since hafnium occurs with zirconium, hafnium can always be a byproduct of extraction to the extent that the low demand requires. The heavy mineral sands ore deposits of the titanium ores ilmenite and rutile yield most of the mined zirconium, zirconium is a good nuclear fuel-rod cladding metal, with the desirable properties of a very low neutron capture cross-section and good chemical stability at high temperatures
38.
Mercury (element)
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Mercury is a chemical element with symbol Hg and atomic number 80. It is commonly known as quicksilver and was formerly named hydrargyrum, Mercury occurs in deposits throughout the world mostly as cinnabar. The red pigment vermilion is obtained by grinding natural cinnabar or synthetic mercuric sulfide, likewise, mechanical pressure gauges and electronic strain gauge sensors have replaced mercury sphygmomanometers. Mercury remains in use in research applications and in amalgam for dental restoration in some locales. It is used in fluorescent lighting, electricity passed through mercury vapor in a fluorescent lamp produces short-wave ultraviolet light which then causes the phosphor in the tube to fluoresce, making visible light. Mercury poisoning can result from exposure to water-soluble forms of mercury, Mercury is a heavy, silvery-white liquid metal. Compared to other metals, it is a conductor of heat. It has a point of −38.83 °C and a boiling point of 356.73 °C. Upon freezing, the volume of mercury decreases by 3. 59%, the coefficient of volume expansion is 181.59 × 10−6 at 0 °C,181.71 × 10−6 at 20 °C and 182.50 × 10−6 at 100 °C. Solid mercury is malleable and ductile and can be cut with a knife, because this configuration strongly resists removal of an electron, mercury behaves similarly to noble gases, which form weak bonds and hence melt at low temperatures. The stability of the 6s shell is due to the presence of a filled 4f shell, an f shell poorly screens the nuclear charge that increases the attractive Coulomb interaction of the 6s shell and the nucleus. Like silver, mercury reacts with hydrogen sulfide. Mercury reacts with solid sulfur flakes, which are used in mercury spill kits to absorb mercury, Mercury dissolves many other metals such as gold and silver to form amalgams. Iron is an exception, and iron flasks have traditionally used to trade mercury. Several other first row transition metals with the exception of manganese, copper, other elements that do not readily form amalgams with mercury include platinum. Sodium amalgam is a reducing agent in organic synthesis, and is also used in high-pressure sodium lamps. Mercury readily combines with aluminium to form a mercury-aluminium amalgam when the two pure metals come into contact, since the amalgam destroys the aluminium oxide layer which protects metallic aluminium from oxidizing in-depth, even small amounts of mercury can seriously corrode aluminium. For this reason, mercury is not allowed aboard an aircraft under most circumstances because of the risk of it forming an amalgam with exposed aluminium parts in the aircraft, Mercury embrittlement is the most common type of liquid metal embrittlement
39.
Indium
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Indium is a chemical element with symbol In and atomic number 49. It is a metal that makes up 0.21 parts per million of the Earths crust. Very soft and malleable, indium has a point higher than sodium and gallium. Chemically, indium is similar to gallium and thallium, and it is intermediate between the two in terms of its properties. Indium was discovered in 1863 by Ferdinand Reich and Hieronymous Theodor Richter by spectroscopic methods and they named it for the indigo blue line in its spectrum. Indium was isolated the next year, Indium is a minor component in zinc sulfide ores and is produced as a byproduct of zinc refinement. Indium has no role, though its compounds are somewhat toxic when injected into the bloodstream. Most occupational exposure is through ingestion, from which indium compounds are not absorbed well, Indium is a silvery-white, highly ductile post-transition metal with a bright luster. It is so soft that like sodium, it can be cut with a knife and it also leaves a visible line on paper. It is a member of group 13 on the periodic table, like tin, a high-pitched cry is heard when indium is bent – a crackling sound due to crystal twinning. Like gallium, indium is able to wet glass, like both, indium has a low melting point,156.60 °C, higher than its lighter homologue, gallium, but lower than its heavier homologue, thallium, and lower than tin. The density of indium,7.31 g/cm3, is greater than gallium. Below the critical temperature,3.41 K, indium becomes a superconductor, Indium displays a ductile viscoplastic response, found to be size-independent in tension and compression. However it does have an effect in bending and indentation, associated to a length-scale of order 50–100 µm. Indium has 49 electrons, with a configuration of 4d105s25p1. In compounds, indium most commonly donates the three outermost electrons to become indium, In3+, in some cases, the pair of 5s-electrons are not donated, resulting in indium, In+. The stabilization of the monovalent state is attributed to the inert pair effect, in which relativistic effects stabilize the 5s-orbital, thallium shows an even stronger effect, causing oxidation to thallium to be more probable than to thallium, whereas gallium commonly shows only the +3 oxidation state. Thus, although thallium is a strong oxidizing agent, indium is not
40.
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
41.
Lilac (color)
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Lilac is a color that is a pale violet tone representing the average color of most lilac flowers. It might also be described as dark mauve or light purple, the colors of some lilac flowers may be equivalent to the colors shown below as pale lilac, rich lilac, or deep lilac. There are other lilac flowers that are colored red-violet, the first recorded use of lilac as an English color name was in 1775. Pale lilac is the color that is represented as lilac in the ISCC-NBS color list, the source of this color is sample 209 in the ISCC-NBS Dictionary of Color Names. The color bright lilac is displayed at right and this is the color called lilac by Crayola in 1994 as one of the colors in its Magic Scent specialty box of colors. Rich lilac, the tone of lilac called lilac in the Pourpre. com color list. Another name for this color is bright French lilac, the color French lilac is displayed at right. This color was formulated for use in design when a medium dark violet color is desired. The first recorded use of French lilac as a name in English was in 1814. The lilac-breasted roller is a member of the family of birds. It is widely distributed in sub-Saharan Africa and the southern Arabian Peninsula, pale lilac was a color associated with the final stages of mourning in English and European cultures. List of colors Lavender Lilac Lilac chaser The dictionary definition of lilac at Wiktionary
42.
Lithium
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Lithium is a chemical element with the symbol Li and atomic number 3. It is a soft, silver-white metal belonging to the metal group of chemical elements. Under standard conditions, it is the lightest metal and the least dense solid element, like all alkali metals, lithium is highly reactive and flammable. For this reason, it is stored in mineral oil. When cut open, it exhibits a metallic luster, but contact with moist air corrodes the surface quickly to a silvery gray. Because of its reactivity, lithium never occurs freely in nature, and instead, appears only in compounds. Lithium occurs in a number of minerals, but due to its solubility as an ion, is present in ocean water and is commonly obtained from brines. On a commercial scale, lithium is isolated electrolytically from a mixture of lithium chloride, the nucleus of the lithium atom verges on instability, since the two stable lithium isotopes found in nature have among the lowest binding energies per nucleon of all stable nuclides. Because of its relative instability, lithium is less common in the solar system than 25 of the first 32 chemical elements even though the nuclei are very light in atomic weight. For related reasons, lithium has important links to nuclear physics, the transmutation of lithium atoms to helium in 1932 was the first fully man-made nuclear reaction, and lithium-6 deuteride serves as a fusion fuel in staged thermonuclear weapons. These uses consume more than three quarters of lithium production, Lithium is found in variable amounts in foods, primary food sources are grains and vegetables, in some areas, the drinking water also provides significant amounts of the element. Human dietary lithium intakes depend on location and the type of foods consumed, traces of lithium were detected in human organs and fetal tissues already in the late 19th century, leading to early suggestions as to possible specific functions in the organism. However, it took another century until evidence for the essentiality of lithium became available, in studies conducted from the 1970s to the 1990s, rats and goats maintained on low-lithium rations were shown to exhibit higher mortalities as well as reproductive and behavioral abnormalities. Lithium appears to play an important role during the early fetal development as evidenced by the high lithium contents of the embryo during the early gestational period. The available experimental evidence now appears to be sufficient to accept lithium as essential, the lithium ion Li+ administered as any of several lithium salts has proven to be useful as a mood-stabilizing drug in the treatment of bipolar disorder in humans. Like the other metals, lithium has a single valence electron that is easily given up to form a cation. Because of this, lithium is a conductor of heat and electricity as well as a highly reactive element. Lithiums low reactivity is due to the proximity of its electron to its nucleus
43.
Carmine (color)
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Carmine is the general term for some deep red colours that are very slightly purplish but are generally slightly closer to red than the colour crimson is. Some rubies are coloured the colour shown below as rich carmine, the first recorded use of carmine as a color name in English was in 1523. The color wild watermelon is displayed at right, ultra red is a color formulated by Crayola in 1972. In 1990, the name of the color was changed to wild watermelon, with a hue code of 350, this color is within the range of carmine colors. This color is supposed to be fluorescent, but there is no mechanism for displaying fluorescence on a computer screen, the Crayola crayon color radical red is displayed at right. The color radical red was formulated by Crayola in 1990, with a hue code of 348, this color is within the range of carmine colors. This color is supposed to be fluorescent, but there is no mechanism for displaying fluorescence on a computer screen, displayed at right is the color paradise pink. The source of color is the Pantone Textile Paper eXtended color list. Since it has a hue code of 347, the color pink is within the range of carmine colors. The rich carmine color tone displayed at right matches the color shown as carmine in the 1930 book A Dictionary of Color and this color is also called Chinese carmine. This is the color referred to as carmine in fashion. This is a tone of carmine pigment used in painting. The color Japanese carmine is shown at right, the name of this color in Japanese is enji-iro, which means cochineal color. Crime Scene Investigation The name is applied to descriptions of blood. Music Carmine is one of the mentioned in Donovans Wear Your Love Like Heaven. Sports Carmines is occasionally used as a nickname for the Boston Red Sox, Carmine is an original colorway of the Air Jordan VI sneaker from 1991. Television The color worn by the Redshirt who wears Star Treks carmine colored engineering uniforms is carmine, in addition, as a play on this, a quickly-dying soldier in the game Gears of War is named Carmine. Underwood responds, You must be a writer, national Flags Carmine is the color used in the flag of Latvia
44.
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
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