Properties
Form and structure
Electrical and thermal
Chemical
Metals are usually inclined to formPeriodic table distribution
In chemistry, the elements which are usually considered to be metals under ordinary conditions are shown in yellow on the periodic table below. The remaining elements are either metalloids (B, Si, Ge, As, Sb, and Te being commonly recognised as such) or nonmetals. Astatine (At) is usually classified as either a nonmetal or a metalloid, but some predictions expect it to be a metal; as such, it has been left blank due to the inconclusive state of the experimental knowledge. The other elements shown as having unknown properties are likely to be metals, but there is some doubt for copernicium (Cn), flerovium (Fl), and oganesson (Og).Alloys
Categories
Metals can be categorised according to their physical or chemical properties. Categories described in the subsections below includeFerrous and non-ferrous metals
The term "ferrous" is derived from theBrittle metal
While nearly all metals are malleable or ductile, a few—beryllium, chromium, manganese, gallium, and bismuth—are brittle. Arsenic and antimony, if admitted as metals, are brittle. Low values of the ratio of bulkRefractory metal
In materials science, metallurgy, and engineering, a refractory metal is a metal that is extraordinarily resistant to heat and wear. Which metals belong to this category varies; the most common definition includes niobium, molybdenum, tantalum, tungsten, and rhenium. They all have melting points above 2000 °C, and a highWhite metal
AHeavy and light metals
A heavy metal is any relatively dense metal orBase, noble, and precious metals
InValve metals
In electrochemistry, a valve metal is a metal which passes current in only one direction.Lifecycle
Formation
:''This sub-section deals with the formation of periodic table elemental metals since these form the basis of metallic materials, as defined in this article.'' Metals up to the vicinity of iron (in the periodic table) are largely made viaAbundance and occurrence
Extraction
Metals are often extracted from the Earth by means of mining ores that are rich sources of the requisite elements, such asUses
Recycling
Biological interactions
The role of metallic elements in the evolution of cell biochemistry has been reviewed, including a detailed section on the role ofHistory
Prehistory
Copper, which occurs in native form, may have been the first metal discovered given its distinctive appearance, heaviness, and malleability compared to other stones or pebbles. Gold, silver, and iron (as meteoric iron), and lead were likewise discovered in prehistory. Forms ofAntiquity
Middle Ages
Arabic and medieval alchemy, alchemists believed that all metals and matter were composed of the principle of sulfur, the father of all metals and carrying the combustible property, and the principle of mercury, the mother of all metals and carrier of the liquidity, fusibility, and volatility properties. These principles were not necessarily the common substances sulfur and mercury (element), mercury found in most laboratories. This theory reinforced the belief that all metals were destined to become gold in the bowels of the earth through the proper combinations of heat, digestion, time, and elimination of contaminants, all of which could be developed and hastened through the knowledge and methods of alchemy. Arsenic, zinc, antimony, and bismuth became known, although these were at first called semimetals or bastard metals on account of their immalleability. All four may have been used incidentally in earlier times without recognising their nature. Albertus Magnus is believed to have been the first to isolate arsenic from a compound in 1250, by heating soap together with arsenic trisulfide. Metallic zinc, which is brittle if impure, was isolated in India by 1300 AD. The first description of a procedure for isolating antimony is in the 1540 book ''De la pirotechnia'' by Vannoccio Biringuccio. Bismuth was described by Agricola in ''De Natura Fossilium'' (c. 1546); it had been confused in early times with tin and lead because of its resemblance to those elements.The Renaissance
Platinum, the third precious metal after gold and silver, was discovered in Ecuador during the period 1736 to 1744, by the Spanish astronomer Antonio de Ulloa and his colleague the mathematician Jorge Juan y Santacilia. Ulloa was the first person to write a scientific description of the metal, in 1748. In 1789, the German chemist Martin Heinrich Klaproth isolated an oxide of uranium, which he thought was the metal itself. Klaproth was subsequently credited as the discoverer of uranium. It was not until 1841, that the French chemist Eugène-Melchior Péligot, prepared the first sample of uranium metal. Henri Becquerel subsequently discovered radioactivity in 1896 by using uranium. In the 1790s, Joseph Priestley and the Dutch chemist Martinus van Marum observed the transformative action of metal surfaces on the dehydrogenation of alcohol, a development which subsequently led, in 1831, to the industrial scale synthesis of sulphuric acid using a platinum catalyst. In 1803, cerium was the first of the lanthanide metals to be discovered, in Bastnäs, Sweden by Jöns Jakob Berzelius and Wilhelm Hisinger, and independently by Martin Heinrich Klaproth in Germany. The lanthanide metals were largely regarded as oddities until the 1960s when methods were developed to more efficiently separate them from one another. They have subsequently found uses in cell phones, magnets, lasers, lighting, batteries, catalytic converters, and in other applications enabling modern technologies. Other metals discovered and prepared during this time were cobalt, nickel, manganese, molybdenum, tungsten, and chromium; and some of theMetal is a mineral body, by nature either liquid or somewhat hard. The latter may be melted by the heat of the fire, but when it has cooled down again and lost all heat, it becomes hard again and resumes its proper form. In this respect it differs from the stone which melts in the fire, for although the latter regain its hardness, yet it loses its pristine form and properties. Traditionally there are six different kinds of metals, namely gold, silver, copper, iron, tin, and lead. There are really others, for mercury (element), quicksilver is a metal, although the Alchemists disagree with us on this subject, and bismuth is also. The ancient Greek writers seem to have been ignorant of bismuth, wherefore Ammonius rightly states that there are many species of metals, animals, and plants which are unknown to us. Stibium when smelted in the crucible and refined has as much right to be regarded as a proper metal as is accorded to lead by writers. If when smelted, a certain portion be added to tin, a bookseller's alloy is produced from which the type is made that is used by those who print books on paper. Each metal has its own form which it preserves when separated from those metals which were mixed with it. Therefore neither electrum nor Stannum [not meaning our tin] is of itself a real metal, but rather an alloy of two metals. Electrum is an alloy of gold and silver, Stannum of lead and silver. And yet if silver be parted from the electrum, then gold remains and not electrum; if silver be taken away from Stannum, then lead remains and not Stannum. Whether brass, however, is found as a native metal or not, cannot be ascertained with any surety. We only know of the artificial brass, which consists of copper tinted with the colour of the mineral calamine. And yet if any should be dug up, it would be a proper metal. Black and white copper seem to be different from the red kind. Metal, therefore, is by nature either solid, as I have stated, or fluid, as in the unique case of quicksilver. But enough now concerning the simple kinds.Georgius Agricola
''De Re Metallica''
(1556) Tr. Herbert Clark Hoover & Lou Henry Hoover (1912); Footnote quoting ''De Natura Fossilium'' (1546), p. 180
Light metals
All metals discovered until 1809 had relatively high densities; their heaviness was regarded as a singularly distinguishing criterion. From 1809 onward, light metals such as sodium, potassium, and strontium were isolated. Their low densities challenged conventional wisdom as to the nature of metals. They behaved chemically as metals however, and were subsequently recognised as such. Aluminum was discovered in 1824 but it was not until 1886 that an industrial large-scale production method was developed. Prices of aluminum dropped and aluminum became widely used in jewelry, everyday items, eyeglass frames, optical instruments, tableware, and foil in the 1890s and early 20th century. Aluminum's ability to form hard yet light alloys with other metals provided the metal many uses at the time. During World War I, major governments demanded large shipments of aluminum for light strong airframes. The most common metal in use for electric power transmission today is aluminum-conductor steel-reinforced cable, aluminum-conductor steel-reinforced. Also seeing much use is all-aluminum-alloy conductor. Aluminum is used because it has about half the weight of a comparable resistance copper cable (though larger diameter due to lower specific conductivity), as well as being cheaper. Copper was more popular in the past and is still in use, especially at lower voltages and for grounding. While pure metallic titanium (99.9%) was first prepared in 1910 it was not used outside the laboratory until 1932. In the 1950s and 1960s, the Soviet Union pioneered the use of titanium in military and submarine applications as part of programs related to the Cold War. Starting in the early 1950s, titanium came into use extensively in military aviation, particularly in high-performance jets, starting with aircraft such as the F-100 Super Sabre and Lockheed A-12 and SR-71. Metallic scandium was produced for the first time in 1937. The first pound of 99% pure scandium metal was produced in 1960. Production of aluminum-scandium alloys began in 1971 following a U.S. patent. Aluminum-scandium alloys were also developed in the USSR.The age of steel
The last stable metallic elements
By 1900 three metals with atomic numbers less than lead (#82), the heaviest stable metal, remained to be discovered: elements 71, 72, 75. Von Welsbach, in 1906, proved that the old ytterbium also contained a new element (#71), which he named ''cassiopeium''. Urbain proved this simultaneously, but his samples were very impure and only contained trace quantities of the new element. Despite this, his chosen name ''lutetium'' was adopted. In 1908, Ogawa found element 75 in thorianite but assigned it as element 43 instead of 75 and named it ''nipponium''. In 1925 Walter Noddack, Ida Eva Tacke, and Otto Berg announced its separation from gadolinite and gave it the present name, ''rhenium''. Georges Urbain claimed to have found element 72 in rare-earth residues, while Vladimir Vernadsky independently found it in orthite. Neither claim was confirmed due to World War I, and neither could be confirmed later, as the chemistry they reported does not match that now known for ''hafnium''. After the war, in 1922, Coster and Hevesy found it by X-ray spectroscopic analysis in Norwegian zircon. Hafnium was thus the last stable element to be discovered.Post-World War II developments
Superalloys
Superalloys composed of combinations of Fe, Ni, Co, and Cr, and lesser amounts of W, Mo, Ta, Nb, Ti, and Al were developed shortly after World War II for use in high performance engines, operating at elevated temperatures (above 650 °C (1,200 °F)). They retain most of their strength under these conditions, for prolonged periods, and combine good low-temperature ductility with resistance to corrosion or oxidation. Superalloys can now be found in a wide range of applications including land, maritime, and aerospace turbines, and chemical and petroleum plants.Transcurium metals
The successful development of the atomic bomb at the end of World War II sparked further efforts to synthesize new elements, nearly all of which are, or are expected to be, metals, and all of which are radioactive. It was not until 1949 that element 97 (berkelium), next after element 96 (curium), was synthesized by firing alpha particles at an americium target. In 1952, element 100 (fermium) was found in the debris of the first hydrogen bomb explosion; hydrogen, a nonmetal, had been identified as an element nearly 200 years earlier. Since 1952, elements 101 (mendelevium) to 118 (oganesson) have been synthesized.Bulk metallic glasses
A metallic glass (also known as an amorphous or glassy metal) is a solid metallic material, usually an alloy, with a disordered atomic-scale structure. Most pure and alloyed metals, in their solid state, have atoms arranged in a highly ordered crystalline structure. Amorphous metals have a non-crystalline glass-like structure. But unlike common glasses, such as window glass, which are typically electrical insulators, amorphous metals have good electrical conductivity. Amorphous metals are produced in several ways, including extremely rapid cooling, physical vapor deposition, solid-state reaction, ion irradiation, and mechanical alloying. The first reported metallic glass was an alloy (Au75Si25) produced at Caltech in 1960. More recently, batches of amorphous steel with three times the strength of conventional steel alloys have been produced. Currently, the most important applications rely on the special magnetic properties of some ferromagnetic metallic glasses. The low magnetization loss is used in high-efficiency transformers. Theft control ID tags and other article surveillance schemes often use metallic glasses because of these magnetic properties.Shape-memory alloys
A shape-memory alloy (SMA) is an alloy that "remembers" its original shape and when deformed returns to its pre-deformed shape when heated. While the shape memory effect had been first observed in 1932, in an Au-Cd alloy, it was not until 1962, with the accidental discovery of the effect in a Ni-Ti alloy that research began in earnest, and another ten years before commercial applications emerged. SMA's have applications in robotics and automotive, aerospace, and biomedical industries. There is another type of SMA, called a ferromagnetic shape-memory alloy (FSMA), that changes shape under strong magnetic fields. These materials are of particular interest as the magnetic response tends to be faster and more efficient than temperature-induced responses.Quasicyrstalline alloys
Complex metallic alloys
Complex metallic alloys (CMAs) are intermetallic compounds characterized by large unit cells comprising some tens up to thousands of atoms; the presence of well-defined clusters of atoms (frequently with icosahedral symmetry); and partial disorder within their crystalline lattices. They are composed of two or more metallic elements, sometimes with metalloids or chalcogenides added. They include, for example, NaCd2, with 348 sodium atoms and 768 cadmium atoms in the unit cell. Linus Pauling attempted to describe the structure of NaCd2 in 1923, but did not succeed until 1955. At first called "giant unit cell crystals", interest in CMAs, as they came to be called, did not pick up until 2002, with the publication of a paper called "Structurally Complex Alloy Phases", given at the ''8th International Conference on Quasicrystals.'' Potential applications of CMAs include as heat insulation; solar heating; magnetic refrigerators; using waste heat to generate electricity; and coatings for turbine blades in military engines.High-entropy alloys
High-entropy alloys (HEAs) such as AlLiMgScTi are composed of equal or nearly equal quantities of five or more metals. Compared to conventional alloys with only one or two base metals, HEAs have considerably better strength-to-weight ratios, higher tensile strength, and greater resistance to fracturing, corrosion, and oxidation. Although HEAs were described as early as 1981, significant interest did not develop until the 2010s; they continue to be the focus of research in materials science and engineering because of their potential for desirable properties.MAX phase alloys
In a MAX phases, MAX phase alloy, M is an early transition metal, A is an A group element (mostly group IIIA and IVA, or groups 13 and 14), and X is either carbon or nitrogen. Examples are Hf2SnC and Ti4AlN3. Such alloys have some of the best properties of metals and ceramics. These properties include high electrical and thermal conductivity, thermal shock resistance, damage tolerance, machinability, high elastic stiffness, and low thermal expansion coefficients.Max phase compositesSee also
* Colored gold * Ductility * Ferrous metallurgy * Metal theft * Metallurgy * Metalworking * Polymetal * Properties of metals, metalloids, and nonmetals * Structural steel * Transition metalNotes
References
Further reading
* Matthew Choptuik, Choptuik M. W., Lehner L. & Pretorias F. 2015, "Probing strong-field gravity through numerical simulation", in Abhay Ashtekar, A. Ashtekar, Beverly Berger, B. K. Berger, J. Isenberg & M. MacCallum (eds), ''General Relativity and Gravitation: A Centennial Perspective'', Cambridge University Press, Cambridge, . * * Crow J. M. 2016,External links