Brass is a metal alloy made of copper and zinc, the proportions of zinc and copper can be varied to create a range of brasses with varying properties. It is an alloy, atoms of the two constituents may replace each other within the same crystal structure. By comparison, bronze is principally an alloy of copper and tin, however and brass may include small proportions of a range of other elements including arsenic, aluminium and silicon. The term is applied to a variety of brasses. Modern practice in museums and archaeology increasingly avoids both terms for objects in favour of the all-embracing copper alloy. It is used in zippers, Brass is often used in situations in which it is important that sparks not be struck, such as in fittings and tools used near flammable or explosive materials. Brass has higher malleability than bronze or zinc, the relatively low melting point of brass and its flow characteristics make it a relatively easy material to cast. By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard, the density of brass is 8.4 to 8.73 grams per cubic centimetre.
Today, almost 90% of all alloys are recycled. Because brass is not ferromagnetic, it can be separated from ferrous scrap by passing the scrap near a powerful magnet, Brass scrap is collected and transported to the foundry where it is melted and recast into billets. Billets are heated and extruded into the form and size. The general softness of brass means that it can often be machined without the use of cutting fluid, aluminium makes brass stronger and more corrosion-resistant. Aluminium causes a highly beneficial hard layer of oxide to be formed on the surface that is thin, transparent. Tin has an effect and finds its use especially in seawater applications. Combinations of iron, aluminium and manganese make brass wear and tear resistant, to enhance the machinability of brass, lead is often added in concentrations of around 2%. Since lead has a melting point than the other constituents of the brass. The pattern the globules form on the surface of the brass increases the available surface area which in turn affects the degree of leaching.
In addition, cutting operations can smear the lead globules over the surface and these effects can lead to significant lead leaching from brasses of comparatively low lead content
A file is a tool used to remove fine amounts of material from a workpiece. It is common in woodworking and other similar trade, most are hand tools, made of a case hardened steel bar of rectangular, triangular, or round cross-section, with one or more surfaces cut with sharp, generally parallel teeth. A narrow, pointed tang is common at one end, to which a handle may be fitted, a rasp is a form of file with distinct, individually cut teeth used for coarsely removing large amounts of material. Files have developed with abrasive surfaces, such as natural or synthetic diamond grains or silicon carbide, allowing removal of material that would dull or resist metal. Relatedly, lapping is ancient, with wood and beach sand offering a natural pair of lap. The Disston authors state, To abrade, or file, ancient man used sand, coral, fish skin, the Bronze Age and the Iron Age had various kinds of files and rasps. Archaeologists have discovered rasps made from bronze in Egypt, dating back to the years 1200–1000 BC, archaeologists have discovered rasps made of iron used by the Assyrians, dating back to the 7th Century BC.
During the Middle Ages files were already advanced, thanks to the extensive talents of blacksmiths. By the 11th century, there already existed hardened files that would seem quite modern even to todays eyes. For example, in the 13th century, ornamental iron work at Paris was done skillfully with the aid of files, but the process was a secret known only to a master craftsman. The Disston authors state, It was not until the fourteenth century, that those who practiced art in ironwork began to use tools, besides heat. This statement could mislead in the sense that stoning and lapping have never been rare activities among humans, but by the late Middle Ages, the transition was extensive. The Disston authors mention Nuremberg and Remscheid as leading centers of production for files as well as tools in general, the activity in Remscheid reflects the metalworking spirit of the Rhine-Ruhr region in general rather than representing a single village of geniuses in isolation. Most files of the period were smithed by hand in a sequence in which the iron was forged, the teeth were cut with a chisel, among the drawings of Leonardo da Vinci is a sketch of a machine tool for the cutting of files.
Prior to the industrialization of machining and the development of parts during the 19th century. Component parts were roughly shaped by forging, and by primitive machining operations and these components were individually hand-fit for assembly by careful and deliberate filing. The potential precision of fitting is much higher than generally assumed. Locks and firearms were manufactured in this way for centuries before the Industrial Revolution, machining in the mid-19th century was heavily dependent on filing, because milling practice was slowly evolving out of its infancy
Aluminium or aluminum is a chemical element in the boron group with symbol Al and atomic number 13. It is a silvery-white, 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, 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 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
Steel wool, known as wire wool or wire sponge, is a bundle of very fine and flexible sharp-edged steel filaments. It was described as a new product in 1896 and it is used as an abrasive in finishing and repair work for polishing wood or metal objects, cleaning household cookware, cleaning windows, and sanding surfaces. Steel wool is made from steel in a process similar to broaching. Steel wool is used by woodworkers and craftsmen working with paint, lacquer. When used on oak, remaining traces of iron may react with tannins in the wood to produce blue or black iron stain, bronze wool or stainless steel wool do not cause this. In many countries, soap-impregnated steel wool pads were sold under trade names for household cleaning. Another use for steel wool is in rodent control, small holes are plugged with coarse grade steel wool, which, if gnawed on by rodents, causes extreme pain in the mouth and, if ingested, severe internal damage may lead to death. When steel wool is heated or allowed to rust it increases in mass due to the combination of oxygen with iron, the fine cross-section of steel wool makes it combustible in air.
Light painting, where many sparks are released, is one application. Very fine steel wool can be used as tinder in emergency situations, as it even when wet and can be ignited by fire. In 2014, steel products are supplied in grades from the coarser grades 3 and 4 to the super fine grade 0000. Rust-resistant steel wool is available, bronze wool Glass wool Mineral wool Polishing Wood finishing
Redox is a chemical reaction in which the oxidation states of atoms are changed. Any such reaction involves both a process and a complementary oxidation process, two key concepts involved with electron transfer processes. Redox reactions include all chemical reactions in which atoms have their oxidation state changed, in general, the chemical species from which the electron is stripped is said to have been oxidized, while the chemical species to which the electron is added is said to have been reduced. It can be explained in terms, Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom. Reduction is the gain of electrons or a decrease in state by a molecule, atom. As an example, during the combustion of wood, oxygen from the air is reduced, the reaction can occur relatively slowly, as in the case of rust, or more quickly, as in the case of fire. Redox is a portmanteau of reduction and oxidation, the word oxidation originally implied reaction with oxygen to form an oxide, since dioxygen was historically the first recognized oxidizing agent.
Later, the term was expanded to encompass oxygen-like substances that accomplished parallel chemical reactions, the meaning was generalized to include all processes involving loss of electrons. The word reduction originally referred to the loss in weight upon heating a metallic ore such as an oxide to extract the metal. In other words, ore was reduced to metal, antoine Lavoisier showed that this loss of weight was due to the loss of oxygen as a gas. Later, scientists realized that the atom gains electrons in this process. The meaning of reduction became generalized to all processes involving gain of electrons. Even though reduction seems counter-intuitive when speaking of the gain of electrons, it help to think of reduction as the loss of oxygen. Since electrons are charged, it is helpful to think of this as reduction in electrical charge. The electrochemist John Bockris has used the words electronation and deelectronation to describe reduction and oxidation processes respectively when they occur at electrodes and these words are analogous to protonation and deprotonation, but they have not been widely adopted by chemists.
The term hydrogenation could be used instead of reduction, since hydrogen is the agent in a large number of reactions. But, unlike oxidation, which has been generalized beyond its root element, the word redox was first used in 1928. The processes of oxidation and reduction occur simultaneously and cannot happen independently of one another, the oxidation alone and the reduction alone are each called a half-reaction, because two half-reactions always occur together to form a whole reaction
Silver is a metallic element with symbol Ag and atomic number 47. The symbol Ag stems from Latin argentum, derived from the Greek ὰργὀς, a soft, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. The metal is found in the Earths crust in the pure, free form, as an alloy with gold and other metals. Most silver is produced as a byproduct of copper, lead, Silver is more abundant than gold, but it is much less abundant as a native metal. Its purity is measured on a per mille basis, a 94%-pure alloy is described as 0.940 fine. As one of the seven metals of antiquity, silver has had a role in most human cultures. Silver has long valued as a precious metal. Silver metal is used in many premodern monetary systems in bullion coins, Silver is used in numerous applications other than currency, such as solar panels, water filtration, ornaments, high-value tableware and utensils, and as an investment medium. Silver is used industrially in electrical contacts and conductors, in specialized mirrors, window coatings, Silver compounds are used in photographic film and X-rays.
Dilute silver nitrate solutions and other compounds are used as disinfectants and microbiocides, added to bandages and wound-dressings, catheters. Silver is similar in its physical and chemical properties to its two neighbours in group 11 of the periodic table and gold. This distinctive electron configuration, with an electron in the highest occupied s subshell over a filled d subshell. Silver is a soft and malleable transition metal. Silver crystallizes in a cubic lattice with bulk coordination number 12. Unlike metals with incomplete d-shells, metallic bonds in silver are lacking a covalent character and are relatively weak and this observation explains the low hardness and high ductility of single crystals of silver. Silver has a brilliant white metallic luster that can take a polish. Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than ~450 nm, at wavelengths shorter than 450 nm, silvers reflectivity is inferior to that of aluminium and drops to zero near 310 nm.
The electrical conductivity of silver is the greatest of all metals, greater even than copper, during World War II in the US,13540 tons of silver were used in electromagnets for enriching uranium, mainly because of the wartime shortage of copper
In chemistry, a nonmetal is a chemical element that mostly lacks metallic attributes. Seventeen elements are classified as nonmetals, most are gases, one is a liquid. Moving rightward across the standard form of the table, nonmetals adopt structures that have progressively fewer nearest neighbours. Polyatomic nonmetals have structures with either three nearest neighbours, as is the case with carbon, or two nearest neighbours in the case of sulfur, diatomic nonmetals, such as hydrogen, have one nearest neighbour, and the monatomic noble gases, such as helium, have none. This gradual fall in the number of nearest neighbours is associated with a reduction in metallic character, the distinction between the three categories of nonmetals, in terms of receding metallicity is not absolute. Boundary overlaps occur as outlying elements in each category show less-distinct, living organisms are composed almost entirely of nonmetals, and nonmetals form many more compounds than metals. There is no definition of a nonmetal.
They show more variability in their properties than metals do, the following are some of the chief characteristics of nonmetals. The elements generally classified as nonmetals include one element in group 1, one in group 14, the distinction between nonmetals and metals is by no means clear. Nonmetals have structures in each atom usually forms bonds with nearest neighbours. Each atom is able to complete its valence shell and attain a stable noble gas configuration. Exceptions to the rule occur with hydrogen, carbon and oxygen, atoms of the latter three elements are sufficiently small such that they are able to form alternative bonding structures, with fewer nearest neighbours. Thus, carbon is able to form its layered graphite structure, the larger size of the remaining non-noble nonmetals weakens their capacity to form multiple bonds and they instead form two or more single bonds to two or more different atoms. Sulfur, for example, forms an eight-membered molecule in which the atoms are arranged in a ring, a similar pattern occurs more generally, at the level of the entire periodic table, in comparing metals and nonmetals.
There is a transition from metallic bonding among the metals on the left of the table through to covalent or Van der Waals bonding among the nonmetals on the right of the table, metallic bonding tends to involve close-packed centrosymmetric structures with a high number of nearest neighbours. Post-transition metals and metalloids, sandwiched between the metals and the nonmetals, tend to have more complex structures with an intermediate number of nearest neighbours. Nonmetallic bonding, towards the right of the table, features open-packed directional structures with fewer or zero nearest neighbours, as is the case with the major categories of metals and nonmetals, there is some variation and overlapping of properties within and across each category of nonmetal. Among the polyatomic nonmetals, carbon and selenium—which border the metalloids—begin to show some metallic character, sulfur, is the least metallic of the polyatomic nonmetals but even here shows some discernible metal-like character
Rust is an iron oxide, usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture. Several forms of rust are distinguishable both visually and by spectroscopy, and form under different circumstances, Rust consists of hydrated iron oxides Fe2O3·nH2O and iron oxide-hydroxide. Given sufficient time and water, any iron mass will eventually convert entirely to rust, surface rust is flaky and friable, and it provides no protection to the underlying iron, unlike the formation of patina on copper surfaces. Rusting is the term for corrosion of iron and its alloys. Many other metals undergo similar corrosion, but the resulting oxides are not commonly called rust, other forms of rust exist, like the result of reactions between iron and chloride in an environment deprived of oxygen. Rebar used in concrete pillars, which generates green rust, is an example. Rust is another name for iron oxide, which occurs when iron or an alloy that contains iron, like steel, is exposed to oxygen and moisture for a long period of time.
Over time, the oxygen combines with the metal at a level, forming a new compound called an oxide. Although some people refer to rust generally as oxidation, that term is more general, although rust forms when iron undergoes oxidation. Only iron or alloys that contain iron can rust, but other metals can corrode in similar ways, the main catalyst for the rusting process is water. Iron or steel structures might appear to be solid, but water molecules can penetrate the microscopic pits, the hydrogen atoms present in water molecules can combine with other elements to form acids, which will eventually cause more metal to be exposed. If chloride ions are present, as is the case with saltwater, the oxygen atoms combine with metallic atoms to form the destructive oxide compound. As the atoms combine, they weaken the metal, making the structure brittle, when impure iron is in contact with water, other strong oxidants, or acids, it rusts. If salt is present, for example in seawater or salt spray, iron metal is relatively unaffected by pure water or by dry oxygen.
As with other metals, like aluminium, a tightly adhering oxide coating, the conversion of the passivating ferrous oxide layer to rust results from the combined action of two agents, usually oxygen and water. Other degrading solutions are sulfur dioxide in water and carbon dioxide in water, under these corrosive conditions, iron hydroxide species are formed. Unlike ferrous oxides, the hydroxides do not adhere to the bulk metal, when iron rusts, the oxides take up more volume than the original metal, this expansion can generate enormous forces, damaging structures made with iron. See Economic effect for more details, the rusting of iron is an electrochemical process that begins with the transfer of electrons from iron to oxygen
Neodymium is a chemical element with symbol Nd and atomic number 60. It is a silvery metal that tarnishes in air. Neodymium was discovered in 1885 by the Austrian chemist Carl Auer von Welsbach and it is present in significant quantities in the ore minerals monazite and bastnäsite. Neodymium is not found naturally in form or unmixed with other lanthanides. Although neodymium is classed as an earth, it is a fairly common element, no rarer than cobalt and copper. Most of the worlds commercial neodymium is mined in China, neodymium compounds were first commercially used as glass dyes in 1927, and they remain a popular additive in glasses. Some neodymium-doped glasses are used in lasers that emit infrared with wavelengths between 1047 and 1062 nanometers. These have been used in applications, such as experiments in inertial confinement fusion. Neodymium is used various other substrate crystals, such as yttrium aluminum garnet in the Nd. This laser usually emits infrared at a wavelength of about 1064 nanometers, the Nd, YAG laser is one of the most commonly used solid-state lasers.
Another important use of neodymium is as a component in the used to make high-strength neodymium magnets—powerful permanent magnets. Larger neodymium magnets are used in electric motors and generators. Neodymium, a rare metal, was present in the classical mischmetal at a concentration of about 18%. Metallic neodymium has a bright, silvery luster, but as one of the more reactive lanthanide rare-earth metals. The oxide layer forms peels off, exposing the metal to further oxidation, thus, a centimeter-sized sample of neodymium completely oxidizes within a year. Neodymium commonly exists in two forms, with a transformation from a double hexagonal to a body-centered cubic structure taking place at about 863 °C. Naturally occurring neodymium is a mixture of five stable isotopes, 142Nd, 143Nd, 145Nd, 146Nd and 148Nd, with 142Nd being the most abundant, and two radioisotopes, 144Nd and 150Nd. In all,31 radioisotopes of neodymium have been detected as of 2010, with the most stable radioisotopes being the naturally occurring ones, 144Nd and 150Nd
A metal is a material that is typically hard, opaque 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 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
A chemical compound is an entity consisting of two or more atoms, at least two from different elements, which associate via chemical bonds. Many chemical compounds have a numerical identifier assigned by the Chemical Abstracts Service. For example, water is composed of two atoms bonded to one oxygen atom, the chemical formula is H2O. A compound can be converted to a different chemical composition by interaction with a chemical compound via a chemical reaction. In this process, bonds between atoms are broken in both of the compounds, and bonds are reformed so that new associations are made between atoms. Schematically, this reaction could be described as AB + CD → AC + BD, where A, B, C, and D are each unique atoms, and AB, CD, AC, and BD are each unique compounds. A chemical element bonded to a chemical element is not a chemical compound since only one element. Examples are the diatomic hydrogen and the polyatomic molecule sulfur. Chemical compounds have a unique and defined chemical structure held together in a spatial arrangement by chemical bonds.
Pure chemical elements are not considered chemical compounds, failing the two or more atom requirement, though they often consist of molecules composed of multiple atoms. There is varying and sometimes inconsistent nomenclature differentiating substances, which include truly non-stoichiometric examples, from chemical compounds, other compounds regarded as chemically identical may have varying amounts of heavy or light isotopes of the constituent elements, which changes the ratio of elements by mass slightly. Characteristic properties of compounds include that elements in a compound are present in a definite proportion, for example, the molecule of the compound water is composed of hydrogen and oxygen in a ratio of 2,1. In addition, compounds have a set of properties. The physical and chemical properties of compounds differ from those of their constituent elements, mixtures can be created by mechanical means alone, but a compound can be created only by a chemical reaction. Some mixtures are so combined that they have some properties similar to compounds.
Other examples of compound-like mixtures include intermetallic compounds and solutions of metals in a liquid form of ammonia. Compounds may be described using formulas in various formats, for compounds that exist as molecules, the formula for the molecular unit is shown. For polymeric materials, such as minerals and many metal oxides, the elements in a chemical formula are normally listed in a specific order, called the Hill system