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114-435: Nickel is a chemical element ; it has symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal . Pure nickel is chemically reactive, but large pieces are slow to react with air under standard conditions because a passivation layer of nickel oxide forms on the surface that prevents further corrosion. Even so, pure native nickel

228-491: A matte for further refining. Hydrometallurgical techniques are also used. Most sulfide deposits have traditionally been processed by concentration through a froth flotation process followed by pyrometallurgical extraction. The nickel matte is further processed with the Sherritt-Gordon process . First, copper is removed by adding hydrogen sulfide , leaving a concentrate of cobalt and nickel. Then, solvent extraction

342-674: A proton–neutron imbalance . Nickel-63 is a contaminant found in the support structure of nuclear reactors. It is produced through neutron capture by nickel-62. Small amounts have also been found near nuclear weapon test sites in the South Pacific. Nickel ores are classified as oxides or sulfides. Oxides include laterite , where the principal mineral mixtures are nickeliferous limonite , (Fe,Ni)O(OH), and garnierite (a mixture of various hydrous nickel and nickel-rich silicates). Nickel sulfides commonly exist as solid solutions with iron in minerals such as pentlandite and pyrrhotite with

456-738: A pure element . In chemistry, a pure element means a substance whose atoms all (or in practice almost all) have the same atomic number, or number of protons . Nuclear scientists, however, define a pure element as one that consists of only one isotope. For example, a copper wire is 99.99% chemically pure if 99.99% of its atoms are copper, with 29 protons each. However it is not isotopically pure since ordinary copper consists of two stable isotopes, 69% Cu and 31% Cu, with different numbers of neutrons. However, pure gold would be both chemically and isotopically pure, since ordinary gold consists only of one isotope, Au. Atoms of chemically pure elements may bond to each other chemically in more than one way, allowing

570-480: A compound, nickel has a number of niche chemical manufacturing uses, such as a catalyst for hydrogenation , cathodes for rechargeable batteries, pigments and metal surface treatments. Nickel is an essential nutrient for some microorganisms and plants that have enzymes with nickel as an active site . Nickel is a silvery-white metal with a slight golden tinge that takes a high polish. It is one of only four elements that are ferromagnetic at or near room temperature;

684-549: A considerable amount of time. (See element naming controversy ). Precursors of such controversies involved the nationalistic namings of elements in the late 19th century. For example, lutetium was named in reference to Paris, France. The Germans were reluctant to relinquish naming rights to the French, often calling it cassiopeium . Similarly, the British discoverer of niobium originally named it columbium , in reference to

798-477: A different element in nuclear reactions , which change an atom's atomic number. Historically, the term "chemical element" meant a substance that cannot be broken down into constituent substances by chemical reactions, and for most practical purposes this definition still has validity. There was some controversy in the 1920s over whether isotopes deserved to be recognized as separate elements if they could be separated by chemical means. The term "(chemical) element"

912-652: A few decay products, to have been differentiated from other elements. Most recently, the synthesis of element 118 (since named oganesson ) was reported in October 2006, and the synthesis of element 117 ( tennessine ) was reported in April 2010. Of these 118 elements, 94 occur naturally on Earth. Six of these occur in extreme trace quantities: technetium , atomic number 43; promethium , number 61; astatine , number 85; francium , number 87; neptunium , number 93; and plutonium , number 94. These 94 elements have been detected in

1026-529: A few elements, such as silver and gold , are found uncombined as relatively pure native element minerals . Nearly all other naturally occurring elements occur in the Earth as compounds or mixtures. Air is mostly a mixture of molecular nitrogen and oxygen , though it does contain compounds including carbon dioxide and water , as well as atomic argon , a noble gas which is chemically inert and therefore does not undergo chemical reactions. The history of

1140-437: A hexa- and heptahydrate useful for electroplating nickel. Common salts of nickel, such as chloride, nitrate, and sulfate, dissolve in water to give green solutions of the metal aquo complex [Ni(H 2 O) 6 ] . The four halides form nickel compounds, which are solids with molecules with octahedral Ni centres. Nickel(II) chloride is most common, and its behavior is illustrative of the other halides. Nickel(II) chloride

1254-563: A lattice of connected "molecules". In 1857 Clausius developed a gas-kinetic model which included the equation for mean free path . In the 1870s it was used to estimate gas molecule sizes, as well as an aforementioned comparison with visible light wavelength and an estimate from the thickness of soap bubble film at which its contractile force rapidly diminishes. By 1900, various estimates of mercury atom diameter averaged around 275±20 pm (modern estimates give 300±10 pm, see below). In 1920, shortly after it had become possible to determine

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1368-399: A meter), or between 0.3 and 3 ångströms . Therefore, the radius of an atom is more than 10,000 times the radius of its nucleus (1–10 fm ), and less than 1/1000 of the wavelength of visible light (400–700 nm ). For many purposes, atoms can be modeled as spheres. This is only a crude approximation, but it can provide quantitative explanations and predictions for many phenomena, such as

1482-500: A pressure of 1 bar and a given temperature (typically at 298.15K). However, for phosphorus, the reference state is white phosphorus even though it is not the most stable allotrope, and the reference state for carbon is graphite, because the structure of graphite is more stable than that of the other allotropes. In thermochemistry , an element is defined to have an enthalpy of formation of zero in its reference state. Several kinds of descriptive categorizations can be applied broadly to

1596-483: A pressure of one atmosphere, are commonly used in characterizing the various elements. While known for most elements, either or both of these measurements is still undetermined for some of the radioactive elements available in only tiny quantities. Since helium remains a liquid even at absolute zero at atmospheric pressure, it has only a boiling point, and not a melting point, in conventional presentations. The density at selected standard temperature and pressure (STP)

1710-711: A public controversy regarding the problems of people with nickel allergy . An estimated 3.6 million tonnes (t) of nickel per year are mined worldwide; Indonesia (1,800,000 t), the Philippines (400,000 t), Russia (200,000 t), New Caledonia ( France ) (230,000 t), Canada (180,000 t) and Australia (160,000 t) are the largest producers as of 2023. The largest nickel deposits in non-Russian Europe are in Finland and Greece . Identified land-based sources averaging at least 1% nickel contain at least 130 million tonnes of nickel. About 60%

1824-469: A relatively high electrical and thermal conductivity for transition metals. The high compressive strength of 34 GPa, predicted for ideal crystals, is never obtained in the real bulk material due to formation and movement of dislocations . However, it has been reached in Ni nanoparticles . Nickel has two atomic electron configurations , [Ar] 3d 4s and [Ar] 3d 4s, which are very close in energy; [Ar] denotes

1938-456: A small group, (the metalloids ), having intermediate properties and often behaving as semiconductors . A more refined classification is often shown in colored presentations of the periodic table. This system restricts the terms "metal" and "nonmetal" to only certain of the more broadly defined metals and nonmetals, adding additional terms for certain sets of the more broadly viewed metals and nonmetals. The version of this classification used in

2052-474: A whole number. For example, the relative atomic mass of chlorine is 35.453 u, which differs greatly from a whole number as it is an average of about 76% chlorine-35 and 24% chlorine-37. Whenever a relative atomic mass value differs by more than ~1% from a whole number, it is due to this averaging effect, as significant amounts of more than one isotope are naturally present in a sample of that element. Chemists and nuclear scientists have different definitions of

2166-409: Is $ 0.045 (90% of the face value). In the 21st century, the high price of nickel has led to some replacement of the metal in coins around the world. Coins still made with nickel alloys include one- and two- euro coins , 5¢, 10¢, 25¢, 50¢, and $ 1 U.S. coins , and 20p, 50p, £1, and £2 UK coins . From 2012 on the nickel-alloy used for 5p and 10p UK coins was replaced with nickel-plated steel. This ignited

2280-543: Is +2, but compounds of Ni , Ni , and Ni are well known, and the exotic oxidation states Ni and Ni have been characterized. Nickel tetracarbonyl (Ni(CO) 4 ), discovered by Ludwig Mond , is a volatile, highly toxic liquid at room temperature. On heating, the complex decomposes back to nickel and carbon monoxide: This behavior is exploited in the Mond process for purifying nickel, as described above. The related nickel(0) complex bis(cyclooctadiene)nickel(0)

2394-404: Is 10 (for tin , element 50). The mass number of an element, A , is the number of nucleons (protons and neutrons) in the atomic nucleus. Different isotopes of a given element are distinguished by their mass number, which is written as a superscript on the left hand side of the chemical symbol (e.g., U). The mass number is always an integer and has units of "nucleons". Thus, magnesium-24 (24

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2508-606: Is a mixture of C (about 98.9%), C (about 1.1%) and about 1 atom per trillion of C. Most (54 of 94) naturally occurring elements have more than one stable isotope. Except for the isotopes of hydrogen (which differ greatly from each other in relative mass—enough to cause chemical effects), the isotopes of a given element are chemically nearly indistinguishable. All elements have radioactive isotopes (radioisotopes); most of these radioisotopes do not occur naturally. Radioisotopes typically decay into other elements via alpha decay , beta decay , or inverse beta decay ; some isotopes of

2622-403: Is a 3d 4s energy level, specifically the 3d(F) 4s F, J  = 4 level. However, each of these two configurations splits into several energy levels due to fine structure , and the two sets of energy levels overlap. The average energy of states with [Ar] 3d 4s is actually lower than the average energy of states with [Ar] 3d 4s. Therefore, the research literature on atomic calculations quotes

2736-406: Is a dimensionless number equal to the atomic mass divided by the atomic mass constant , which equals 1 Da. In general, the mass number of a given nuclide differs in value slightly from its relative atomic mass, since the mass of each proton and neutron is not exactly 1 Da; since the electrons contribute a lesser share to the atomic mass as neutron number exceeds proton number; and because of

2850-722: Is a new nickel mine in Michigan's Upper Peninsula . Construction was completed in 2013, and operations began in the third quarter of 2014. In the first full year of operation, the Eagle Mine produced 18,000 t. Nickel is obtained through extractive metallurgy : it is extracted from ore by conventional roasting and reduction processes that yield metal of greater than 75% purity. In many stainless steel applications, 75% pure nickel can be used without further purification, depending on impurities. Traditionally, most sulfide ores are processed using pyrometallurgical techniques to produce

2964-429: Is a useful catalyst in organonickel chemistry because the cyclooctadiene (or cod ) ligands are easily displaced. Nickel(I) complexes are uncommon, but one example is the tetrahedral complex NiBr(PPh 3 ) 3 . Many nickel(I) complexes have Ni–Ni bonding, such as the dark red diamagnetic K 4 [Ni 2 (CN) 6 ] prepared by reduction of K 2 [Ni 2 (CN) 6 ] with sodium amalgam . This compound

3078-471: Is also formed in nickel distillation as a by-product, but it decomposes to tetracobalt dodecacarbonyl at the reaction temperature to give a non-volatile solid. Chemical element A chemical element is a chemical substance whose atoms all have the same number of protons . The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8, meaning each oxygen atom has 8 protons in its nucleus. Atoms of

3192-812: Is an ongoing area of scientific study. The lightest elements are hydrogen and helium , both created by Big Bang nucleosynthesis in the first 20 minutes of the universe in a ratio of around 3:1 by mass (or 12:1 by number of atoms), along with tiny traces of the next two elements, lithium and beryllium . Almost all other elements found in nature were made by various natural methods of nucleosynthesis . On Earth, small amounts of new atoms are naturally produced in nucleogenic reactions, or in cosmogenic processes, such as cosmic ray spallation . New atoms are also naturally produced on Earth as radiogenic daughter isotopes of ongoing radioactive decay processes such as alpha decay , beta decay , spontaneous fission , cluster decay , and other rarer modes of decay. Of

3306-460: Is based on a Latin or other traditional word, for example adopting "gold" rather than "aurum" as the name for the 79th element (Au). IUPAC prefers the British spellings " aluminium " and "caesium" over the U.S. spellings "aluminum" and "cesium", and the U.S. "sulfur" over British "sulphur". However, elements that are practical to sell in bulk in many countries often still have locally used national names, and countries whose national language does not use

3420-700: Is currently being set in place by the International Seabed Authority to ensure that these nodules are collected in an environmentally conscientious manner while adhering to the United Nations Sustainable Development Goals . The one place in the United States where nickel has been profitably mined is Riddle, Oregon , with several square miles of nickel-bearing garnierite surface deposits. The mine closed in 1987. The Eagle mine project

3534-598: Is found in Earth's crust only in tiny amounts, usually in ultramafic rocks , and in the interiors of larger nickel–iron meteorites that were not exposed to oxygen when outside Earth's atmosphere. Meteoric nickel is found in combination with iron , a reflection of the origin of those elements as major end products of supernova nucleosynthesis . An iron–nickel mixture is thought to compose Earth's outer and inner cores . Use of nickel (as natural meteoric nickel–iron alloy) has been traced as far back as 3500 BCE. Nickel

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3648-468: Is greater than both Fe and Fe , more abundant nuclides often incorrectly cited as having the highest binding energy. Though this would seem to predict nickel as the most abundant heavy element in the universe, the high rate of photodisintegration of nickel in stellar interiors causes iron to be by far the most abundant. Nickel-60 is the daughter product of the extinct radionuclide Fe (half-life 2.6 million years). Due to

3762-572: Is in laterites and 40% is in sulfide deposits. Also, extensive nickel sources are found in the depths of the Pacific Ocean , especially in an area called the Clarion Clipperton Zone in the form of polymetallic nodules peppering the seafloor at 3.5–6 km below sea level . These nodules are composed of numerous rare-earth metals and are estimated to be 1.7% nickel. With advances in science and engineering , regulation

3876-405: Is known as shielding —which explains why the size of atoms usually increases down each column despite an increase in attractive force from the nucleus. Electron shielding causes the attraction of an atom's nucleus on its electrons to decrease, so electrons occupying higher energy states farther from the nucleus experience reduced attractive force, increasing the size of the atom. However, elements in

3990-542: Is made by dissolving nickel or its oxide in hydrochloric acid . It is usually found as the green hexahydrate, whose formula is usually written NiCl 2 ·6H 2 O . When dissolved in water, this salt forms the metal aquo complex [Ni(H 2 O) 6 ] . Dehydration of NiCl 2 ·6H 2 O gives yellow anhydrous NiCl 2 . Some tetracoordinate nickel(II) complexes, e.g. bis(triphenylphosphine)nickel chloride , exist both in tetrahedral and square planar geometries. The tetrahedral complexes are paramagnetic ;

4104-453: Is now Syria have been found to contain as much as 2% nickel. Some ancient Chinese manuscripts suggest that "white copper" ( cupronickel , known as baitong ) was used there in 1700–1400 BCE. This Paktong white copper was exported to Britain as early as the 17th century, but the nickel content of this alloy was not discovered until 1822. Coins of nickel-copper alloy were minted by Bactrian kings Agathocles , Euthydemus II , and Pantaleon in

4218-431: Is now known as the mineral nickeline (formerly niccolite ), a nickel arsenide . In 1751, Baron Axel Fredrik Cronstedt tried to extract copper from kupfernickel at a cobalt mine in the village of Los, Sweden , and instead produced a white metal that he named nickel after the spirit that had given its name to the mineral. In modern German, Kupfernickel or Kupfer-Nickel designates the alloy cupronickel . Originally,

4332-436: Is often used in characterizing the elements. Density is often expressed in grams per cubic centimetre (g/cm ). Since several elements are gases at commonly encountered temperatures, their densities are usually stated for their gaseous forms; when liquefied or solidified, the gaseous elements have densities similar to those of the other elements. When an element has allotropes with different densities, one representative allotrope

4446-491: Is oxidized in water, liberating H 2 . It is thought that the nickel(I) oxidation state is important to nickel-containing enzymes, such as [NiFe]-hydrogenase , which catalyzes the reversible reduction of protons to H 2 . Nickel(II) forms compounds with all common anions, including sulfide , sulfate , carbonate, hydroxide, carboxylates, and halides. Nickel(II) sulfate is produced in large amounts by dissolving nickel metal or oxides in sulfuric acid , forming both

4560-468: Is produced by the silicon burning process and later set free in large amounts in type Ia supernovae . The shape of the light curve of these supernovae at intermediate to late-times corresponds to the decay via electron capture of Ni to cobalt -56 and ultimately to iron-56. Nickel-59 is a long-lived cosmogenic radionuclide ; half-life 76,000 years. Ni has found many applications in isotope geology . Ni has been used to date

4674-426: Is the mass number) is an atom with 24 nucleons (12 protons and 12 neutrons). Whereas the mass number simply counts the total number of neutrons and protons and is thus an integer, the atomic mass of a particular isotope (or "nuclide") of the element is the mass of a single atom of that isotope, and is typically expressed in daltons (symbol: Da), or universal atomic mass units (symbol: u). Its relative atomic mass

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4788-532: Is typically selected in summary presentations, while densities for each allotrope can be stated where more detail is provided. For example, the three familiar allotropes of carbon ( amorphous carbon , graphite , and diamond ) have densities of 1.8–2.1, 2.267, and 3.515 g/cm , respectively. The elements studied to date as solid samples have eight kinds of crystal structures : cubic , body-centered cubic , face-centered cubic, hexagonal , monoclinic , orthorhombic , rhombohedral , and tetragonal . For some of

4902-474: Is used as the cathode in many rechargeable batteries , including nickel–cadmium , nickel–iron , nickel–hydrogen , and nickel–metal hydride , and used by certain manufacturers in Li-ion batteries . Ni(IV) remains a rare oxidation state and very few compounds are known. Ni(IV) occurs in the mixed oxide BaNiO 3 . Unintentional use of nickel can be traced back as far as 3500 BCE. Bronzes from what

5016-453: Is used chiefly in alloys and corrosion-resistant plating. About 68% of world production is used in stainless steel . A further 10% is used for nickel-based and copper-based alloys, 9% for plating, 7% for alloy steels, 3% in foundries, and 4% in other applications such as in rechargeable batteries, including those in electric vehicles (EVs). Nickel is widely used in coins , though nickel-plated objects sometimes provoke nickel allergy . As

5130-417: Is used in two different but closely related meanings: it can mean a chemical substance consisting of a single kind of atoms, or it can mean that kind of atoms as a component of various chemical substances. For example, molecules of water (H 2 O) contain atoms of hydrogen (H) and oxygen (O), so water can be said as a compound consisting of the elements hydrogen (H) and oxygen (O) even though it does not contain

5244-410: Is used to separate the cobalt and nickel, with the final nickel content greater than 86%. A second common refining process is leaching the metal matte into a nickel salt solution, followed by electrowinning the nickel from solution by plating it onto a cathode as electrolytic nickel. The purest metal is obtained from nickel oxide by the Mond process , which gives a purity of over 99.99%. The process

5358-429: Is very strong; fullerenes , which have nearly spherical shapes; and carbon nanotubes , which are tubes with a hexagonal structure (even these may differ from each other in electrical properties). The ability of an element to exist in one of many structural forms is known as 'allotropy'. The reference state of an element is defined by convention, usually as the thermodynamically most stable allotrope and physical state at

5472-590: Is widely used. For example, the French chemical terminology distinguishes élément chimique (kind of atoms) and corps simple (chemical substance consisting of a single kind of atoms); the Russian chemical terminology distinguishes химический элемент and простое вещество . Almost all baryonic matter in the universe is composed of elements (among rare exceptions are neutron stars ). When different elements undergo chemical reactions, atoms are rearranged into new compounds held together by chemical bonds . Only

5586-489: The International Union of Pure and Applied Chemistry (IUPAC) had recognized a total of 118 elements. The first 94 occur naturally on Earth , and the remaining 24 are synthetic elements produced in nuclear reactions. Save for unstable radioactive elements (radioelements) which decay quickly, nearly all elements are available industrially in varying amounts. The discovery and synthesis of further new elements

5700-638: The Latin alphabet are likely to use the IUPAC element names. According to IUPAC, element names are not proper nouns; therefore, the full name of an element is not capitalized in English, even if derived from a proper noun , as in californium and einsteinium . Isotope names are also uncapitalized if written out, e.g., carbon-12 or uranium-235 . Chemical element symbols (such as Cf for californium and Es for einsteinium), are always capitalized (see below). In

5814-598: The New World . It was used extensively as such by American publications before the international standardization (in 1950). Before chemistry became a science , alchemists designed arcane symbols for both metals and common compounds. These were however used as abbreviations in diagrams or procedures; there was no concept of atoms combining to form molecules . With his advances in the atomic theory of matter, John Dalton devised his own simpler symbols, based on circles, to depict molecules. Atomic radius Depending on

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5928-419: The density of liquids and solids, the diffusion of fluids through molecular sieves , the arrangement of atoms and ions in crystals , and the size and shape of molecules . The concept of atomic radius was preceded in the 19th century by the concept of atomic volume, a relative measure of how much space would on average an atom occupy in a given solid or liquid material. By the end of the century this term

6042-423: The kinetic isotope effect is significant). Thus, all carbon isotopes have nearly identical chemical properties because they all have six electrons, even though they may have 6 to 8 neutrons. That is why atomic number, rather than mass number or atomic weight , is considered the identifying characteristic of an element. The symbol for atomic number is Z . Isotopes are atoms of the same element (that is, with

6156-405: The nuclear binding energy and electron binding energy. For example, the atomic mass of chlorine-35 to five significant digits is 34.969 Da and that of chlorine-37 is 36.966 Da. However, the relative atomic mass of each isotope is quite close to its mass number (always within 1%). The only isotope whose atomic mass is exactly a natural number is C, which has a mass of 12 Da; because

6270-538: The 2nd century BCE, possibly out of the Chinese cupronickel. In medieval Germany, a metallic yellow mineral was found in the Ore Mountains that resembled copper ore. But when miners were unable to get any copper from it, they blamed a mischievous sprite of German mythology, Nickel (similar to Old Nick ), for besetting the copper. They called this ore Kupfernickel from German Kupfer 'copper'. This ore

6384-435: The 5d-block ( lutetium to mercury ) are much smaller than this trend predicts due to the weak shielding of the 4f-subshell. This phenomenon is known as the lanthanide contraction . A similar phenomenon exists for actinides ; however, the general instability of transuranic elements makes measurements for the remainder of the 5f-block difficult and for transactinides nearly impossible. Finally, for sufficiently heavy elements,

6498-638: The 94 naturally occurring elements, those with atomic numbers 1 through 82 each have at least one stable isotope (except for technetium , element 43 and promethium , element 61, which have no stable isotopes). 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. Some of these elements, notably bismuth (atomic number 83), thorium (atomic number 90), and uranium (atomic number 92), have one or more isotopes with half-lives long enough to survive as remnants of

6612-487: The French, Italians, Greeks, Portuguese and Poles prefer "azote/azot/azoto" (from roots meaning "no life") for "nitrogen". For purposes of international communication and trade, the official names of the chemical elements both ancient and more recently recognized are decided by the International Union of Pure and Applied Chemistry (IUPAC), which has decided on a sort of international English language, drawing on traditional English names even when an element's chemical symbol

6726-504: The United States, the term "nickel" or "nick" originally applied to the copper-nickel Flying Eagle cent , which replaced copper with 12% nickel 1857–58, then the Indian Head cent of the same alloy from 1859 to 1864. Still later, in 1865, the term designated the three-cent nickel , with nickel increased to 25%. In 1866, the five-cent shield nickel (25% nickel, 75% copper) appropriated the designation, which has been used ever since for

6840-459: The alloys kamacite and taenite . Nickel in meteorites was first detected in 1799 by Joseph-Louis Proust , a French chemist who then worked in Spain. Proust analyzed samples of the meteorite from Campo del Cielo (Argentina), which had been obtained in 1783 by Miguel Rubín de Celis, discovering the presence in them of nickel (about 10%) along with iron. The most common oxidation state of nickel

6954-427: The atom's electrons. The greater attraction draws the electrons closer to the protons, decreasing the size of the atom. Down each group, the atomic radius of each element typically increases because there are more occupied electron energy levels and therefore a greater distance between protons and electrons. The increasing nuclear charge is partly counterbalanced by the increasing number of electrons—a phenomenon that

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7068-487: The atomic masses of the elements (their atomic weights or atomic masses) do not always increase monotonically with their atomic numbers. The naming of various substances now known as elements precedes the atomic theory of matter, as names were given locally by various cultures to various minerals, metals, compounds, alloys, mixtures, and other materials, though at the time it was not known which chemicals were elements and which compounds. As they were identified as elements,

7182-504: The atomic radius may be decreased by relativistic effects . This is a consequence of electrons near the strongly charged nucleus traveling at a sufficient fraction of the speed of light to gain a nontrivial amount of mass. The following table summarizes the main phenomena that influence the atomic radius of an element: The electrons in the 4f- subshell , which is progressively filled from lanthanum ( Z  = 57) to ytterbium ( Z  = 70), are not particularly effective at shielding

7296-413: The chemical substances (di)hydrogen (H 2 ) and (di)oxygen (O 2 ), as H 2 O molecules are different from H 2 and O 2 molecules. For the meaning "chemical substance consisting of a single kind of atoms", the terms "elementary substance" and "simple substance" have been suggested, but they have not gained much acceptance in English chemical literature, whereas in some other languages their equivalent

7410-462: The complete argon core structure. There is some disagreement on which configuration has the lower energy. Chemistry textbooks quote nickel's electron configuration as [Ar] 4s 3d, also written [Ar] 3d 4s. This configuration agrees with the Madelung energy ordering rule , which predicts that 4s is filled before 3d. It is supported by the experimental fact that the lowest energy state of the nickel atom

7524-408: The dalton is defined as 1/12 of the mass of a free neutral carbon-12 atom in the ground state. The standard atomic weight (commonly called "atomic weight") of an element is the average of the atomic masses of all the chemical element's isotopes as found in a particular environment, weighted by isotopic abundance, relative to the atomic mass unit. This number may be a fraction that is not close to

7638-501: The definition, the term may apply to atoms in condensed matter , covalently bonding in molecules , or in ionized and excited states ; and its value may be obtained through experimental measurements, or computed from theoretical models. The value of the radius may depend on the atom's state and context. Electrons do not have definite orbits nor sharply defined ranges. Rather, their positions must be described as probability distributions that taper off gradually as one moves away from

7752-416: The discovery and use of elements began with early human societies that discovered native minerals like carbon , sulfur , copper and gold (though the modern concept of an element was not yet understood). Attempts to classify materials such as these resulted in the concepts of classical elements , alchemy , and similar theories throughout history. Much of the modern understanding of elements developed from

7866-699: The earth's crust exists as oxides, economically more important nickel ores are sulfides, especially pentlandite . Major production sites include the Sudbury region , Canada (which is thought to be of meteoric origin), New Caledonia in the Pacific , Western Australia , and Norilsk , Russia. Nickel is one of four elements (the others are iron , cobalt , and gadolinium ) that are ferromagnetic at about room temperature. Alnico permanent magnets based partly on nickel are of intermediate strength between iron-based permanent magnets and rare-earth magnets . The metal

7980-406: The elements are available by name, atomic number, density, melting point, boiling point and chemical symbol , as well as ionization energy . The nuclides of stable and radioactive elements are also available as a list of nuclides , sorted by length of half-life for those that are unstable. One of the most convenient, and certainly the most traditional presentation of the elements, is in the form of

8094-470: The elements are often summarized using the periodic table, which powerfully and elegantly organizes the elements by increasing atomic number into rows ( "periods" ) in which the columns ( "groups" ) share recurring ("periodic") physical and chemical properties. The table contains 118 confirmed elements as of 2021. Although earlier precursors to this presentation exist, its invention is generally credited to Russian chemist Dmitri Mendeleev in 1869, who intended

8208-480: The elements can be uniquely sequenced by atomic number, conventionally from lowest to highest (as in a periodic table), sets of elements are sometimes specified by such notation as "through", "beyond", or "from ... through", as in "through iron", "beyond uranium", or "from lanthanum through lutetium". The terms "light" and "heavy" are sometimes also used informally to indicate relative atomic numbers (not densities), as in "lighter than carbon" or "heavier than lead", though

8322-413: The elements without any stable isotopes are technetium (atomic number 43), promethium (atomic number 61), and all observed elements with atomic number greater than 82. Of the 80 elements with at least one stable isotope, 26 have only one stable isotope. The mean number of stable isotopes for the 80 stable elements is 3.1 stable isotopes per element. The largest number of stable isotopes for a single element

8436-481: The elements, as published by J. C. Slater in 1964. The values are in picometers (pm or 1×10  m), with an accuracy of about 5 pm. The shade of the box ranges from red to yellow as the radius increases; gray indicates lack of data. Electrons in atoms fill electron shells from the lowest available energy level. As a consequence of the Aufbau principle , each new period begins with the first two elements filling

8550-474: The elements, including consideration of their general physical and chemical properties, their states of matter under familiar conditions, their melting and boiling points, their densities, their crystal structures as solids, and their origins. Several terms are commonly used to characterize the general physical and chemical properties of the chemical elements. A first distinction is between metals , which readily conduct electricity , nonmetals , which do not, and

8664-492: The existing names for anciently known elements (e.g., gold, mercury, iron) were kept in most countries. National differences emerged over the element names either for convenience, linguistic niceties, or nationalism. For example, German speakers use "Wasserstoff" (water substance) for "hydrogen", "Sauerstoff" (acid substance) for "oxygen" and "Stickstoff" (smothering substance) for "nitrogen"; English and some other languages use "sodium" for "natrium", and "potassium" for "kalium"; and

8778-630: The explosive stellar nucleosynthesis that produced the heavy metals before the formation of our Solar System . At over 1.9 × 10 years, over a billion times longer than the estimated age of the universe, bismuth-209 has the longest known alpha decay half-life of any isotope, and is almost always considered on par with the 80 stable elements. The heaviest elements (those beyond plutonium, element 94) undergo radioactive decay with half-lives so short that they are not found in nature and must be synthesized . There are now 118 known elements. In this context, "known" means observed well enough, even from just

8892-529: The formation of Earth, they are certain to have completely decayed, and if present in novae, are in quantities too small to have been noted. Technetium was the first purportedly non-naturally occurring element synthesized, in 1937, though trace amounts of technetium have since been found in nature (and also the element may have been discovered naturally in 1925). This pattern of artificial production and later natural discovery has been repeated with several other radioactive naturally occurring rare elements. List of

9006-429: The formula Fe 9-x Ni x S 8 and Fe 7-x Ni x S 6 , respectively. Other common Ni-containing minerals are millerite and the arsenide niccolite . Identified land-based resources throughout the world averaging 1% nickel or greater comprise at least 130 million tons of nickel (about the double of known reserves). About 60% is in laterites and 40% in sulfide deposits. On geophysical evidence, most of

9120-472: The ground state configuration as [Ar] 3d 4s. The isotopes of nickel range in atomic weight from 48  u ( Ni ) to 82 u ( Ni ). Natural nickel is composed of five stable isotopes , Ni , Ni , Ni , Ni and Ni , of which Ni is the most abundant (68.077% natural abundance ). Nickel-62 has the highest binding energy per nucleon of any nuclide : 8.7946 MeV/nucleon. Its binding energy

9234-431: The half-lives predicted for the observationally stable lead isotopes range from 10 to 10 years. Elements with atomic numbers 43, 61, and 83 through 94 are unstable enough that their radioactive decay can be detected. Three of these elements, bismuth (element 83), thorium (90), and uranium (92) have one or more isotopes with half-lives long enough to survive as remnants of the explosive stellar nucleosynthesis that produced

9348-399: The heaviest elements also undergo spontaneous fission . Isotopes that are not radioactive, are termed "stable" isotopes. All known stable isotopes occur naturally (see primordial nuclide ). The many radioisotopes that are not found in nature have been characterized after being artificially produced. Certain elements have no stable isotopes and are composed only of radioisotopes: specifically

9462-549: The heavy elements before the formation of the Solar System. For example, at over 1.9 × 10 years, over a billion times longer than the estimated age of the universe, bismuth-209 has the longest known alpha decay half-life of any isotope. The last 24 elements (those beyond plutonium, element 94) undergo radioactive decay with short half-lives and cannot be produced as daughters of longer-lived elements, and thus are not known to occur in nature at all. 1 The properties of

9576-493: The increasing nuclear charge from the sub-shells further out. The elements immediately following the lanthanides have atomic radii which are smaller than would be expected and which are almost identical to the atomic radii of the elements immediately above them. Hence lutetium is in fact slightly smaller than yttrium , hafnium has virtually the same atomic radius (and chemistry) as zirconium , and tantalum has an atomic radius similar to niobium , and so forth. The effect of

9690-429: The lanthanide contraction is noticeable up to platinum ( Z  = 78), after which it is masked by a relativistic effect known as the inert-pair effect . Due to lanthanide contraction, the 5 following observations can be drawn: The d-block contraction is less pronounced than the lanthanide contraction but arises from a similar cause. In this case, it is the poor shielding capacity of the 3d-electrons which affects

9804-748: The large deposits in the Sudbury Basin in Canada in 1883, in Norilsk -Talnakh in Russia in 1920, and in the Merensky Reef in South Africa in 1924 made large-scale nickel production possible. Aside from the aforementioned Bactrian coins, nickel was not a component of coins until the mid-19th century. 99.9% nickel five-cent coins were struck in Canada (the world's largest nickel producer at

9918-721: The long half-life of Fe , its persistence in materials in the Solar System may generate observable variations in the isotopic composition of Ni . Therefore, the abundance of Ni in extraterrestrial material may give insight into the origin of the Solar System and its early history. At least 26 nickel radioisotopes have been characterized; the most stable are Ni with half-life 76,000 years, Ni (100 years), and Ni (6 days). All other radioisotopes have half-lives less than 60 hours and most these have half-lives less than 30 seconds. This element also has one meta state . Radioactive nickel-56

10032-414: The metals at a profit. The United States Mint , anticipating this practice, implemented new interim rules on December 14, 2006, subject to public comment for 30 days, which criminalized the melting and export of cents and nickels. Violators can be punished with a fine of up to $ 10,000 and/or a maximum of five years in prison. As of September 19, 2013, the melt value of a US nickel (copper and nickel included)

10146-406: The next unoccupied s-orbital . Because an atom's s-orbital electrons are typically farthest from the nucleus, this results in a significant increase in atomic radius with the first elements of each period. The atomic radius of each element generally decreases across each period due to an increasing number of protons, since an increase in the number of protons increases the attractive force acting on

10260-435: The nickel on Earth is believed to be in Earth's outer and inner cores . Kamacite and taenite are naturally occurring alloys of iron and nickel. For kamacite, the alloy is usually in the proportion of 90:10 to 95:5, though impurities (such as cobalt or carbon ) may be present. Taenite is 20% to 65% nickel. Kamacite and taenite are also found in nickel iron meteorites . Nickel is commonly found in iron meteorites as

10374-405: The nucleus, without a sharp cutoff; these are referred to as atomic orbitals or electron clouds. Moreover, in condensed matter and molecules, the electron clouds of the atoms usually overlap to some extent, and some of the electrons may roam over a large region encompassing two or more atoms. Under most definitions the radii of isolated neutral atoms range between 30 and 300 pm ( trillionths of

10488-509: The only source for nickel was the rare Kupfernickel. Beginning in 1824, nickel was obtained as a byproduct of cobalt blue production. The first large-scale smelting of nickel began in Norway in 1848 from nickel-rich pyrrhotite . The introduction of nickel in steel production in 1889 increased the demand for nickel; the nickel deposits of New Caledonia , discovered in 1865, provided most of the world's supply between 1875 and 1915. The discovery of

10602-424: The others are iron, cobalt and gadolinium . Its Curie temperature is 355 °C (671 °F), meaning that bulk nickel is non-magnetic above this temperature. The unit cell of nickel is a face-centered cube ; it has lattice parameter of 0.352 nm, giving an atomic radius of 0.124 nm. This crystal structure is stable to pressures of at least 70 GPa. Nickel is hard, malleable and ductile , and has

10716-418: The periodic table, which groups together elements with similar chemical properties (and usually also similar electronic structures). The atomic number of an element is equal to the number of protons in each atom, and defines the element. For example, all carbon atoms contain 6 protons in their atomic nucleus ; so the atomic number of carbon is 6. Carbon atoms may have different numbers of neutrons; atoms of

10830-426: The periodic tables presented here includes: actinides , alkali metals , alkaline earth metals , halogens , lanthanides , transition metals , post-transition metals , metalloids , reactive nonmetals , and noble gases . In this system, the alkali metals, alkaline earth metals, and transition metals, as well as the lanthanides and the actinides, are special groups of the metals viewed in a broader sense. Similarly,

10944-412: The pure element to exist in multiple chemical structures ( spatial arrangements of atoms ), known as allotropes , which differ in their properties. For example, carbon can be found as diamond , which has a tetrahedral structure around each carbon atom; graphite , which has layers of carbon atoms with a hexagonal structure stacked on top of each other; graphene , which is a single layer of graphite that

11058-772: The reactive nonmetals and the noble gases are nonmetals viewed in the broader sense. In some presentations, the halogens are not distinguished, with astatine identified as a metalloid and the others identified as nonmetals. Another commonly used basic distinction among the elements is their state of matter (phase), whether solid , liquid , or gas , at standard temperature and pressure (STP). Most elements are solids at STP, while several are gases. Only bromine and mercury are liquid at 0 degrees Celsius (32 degrees Fahrenheit) and 1 atmosphere pressure; caesium and gallium are solid at that temperature, but melt at 28.4°C (83.2°F) and 29.8°C (85.6°F), respectively. Melting and boiling points , typically expressed in degrees Celsius at

11172-919: The remaining 11 elements have half lives too short for them to have been present at the beginning of the Solar System, and are therefore considered transient elements. Of these 11 transient elements, five ( polonium , radon , radium , actinium , and protactinium ) are relatively common decay products of thorium and uranium . The remaining six transient elements (technetium, promethium, astatine, francium , neptunium , and plutonium ) occur only rarely, as products of rare decay modes or nuclear reaction processes involving uranium or other heavy elements. Elements with atomic numbers 1 through 82, except 43 (technetium) and 61 (promethium), each have at least one isotope for which no radioactive decay has been observed. Observationally stable isotopes of some elements (such as tungsten and lead ), however, are predicted to be slightly radioactive with very long half-lives: for example,

11286-624: The same element can have different numbers of neutrons in their nuclei, known as isotopes of the element. Two or more atoms can combine to form molecules . Some elements are formed from molecules of identical atoms , e. g. atoms of hydrogen (H) form diatomic molecules (H 2 ). Chemical compounds are substances made of atoms of different elements; they can have molecular or non-molecular structure. Mixtures are materials containing different chemical substances; that means (in case of molecular substances) that they contain different types of molecules. Atoms of one element can be transformed into atoms of

11400-495: The same element having different numbers of neutrons are known as isotopes of the element. The number of protons in the nucleus also determines its electric charge , which in turn determines the number of electrons of the atom in its non-ionized state. The electrons are placed into atomic orbitals that determine the atom's chemical properties . The number of neutrons in a nucleus usually has very little effect on an element's chemical properties; except for hydrogen (for which

11514-404: The same number of protons in their nucleus), but having different numbers of neutrons . Thus, for example, there are three main isotopes of carbon. All carbon atoms have 6 protons, but they can have either 6, 7, or 8 neutrons. Since the mass numbers of these are 12, 13 and 14 respectively, said three isotopes are known as carbon-12 , carbon-13 , and carbon-14 ( C, C, and C). Natural carbon

11628-457: The second half of the 20th century, physics laboratories became able to produce elements with half-lives too short for an appreciable amount of them to exist at any time. These are also named by IUPAC, which generally adopts the name chosen by the discoverer. This practice can lead to the controversial question of which research group actually discovered an element, a question that delayed the naming of elements with atomic number of 104 and higher for

11742-457: The sizes of atoms using X-ray crystallography , it was suggested that all atoms of the same element have the same radii. However, in 1923, when more crystal data had become available, it was found that the approximation of an atom as a sphere does not necessarily hold when comparing the same atom in different crystal structures. Widely used definitions of atomic radius include: The following table shows empirically measured covalent radii for

11856-630: The square planar complexes are diamagnetic . In having properties of magnetic equilibrium and formation of octahedral complexes, they contrast with the divalent complexes of the heavier group 10 metals, palladium(II) and platinum(II), which form only square-planar geometry. Nickelocene has an electron count of 20. Many chemical reactions of nickelocene tend to yield 18-electron products. Many Ni(III) compounds are known. Ni(III) forms simple salts with fluoride or oxide ions. Ni(III) can be stabilized by σ-donor ligands such as thiols and organophosphines . Ni(III) occurs in nickel oxide hydroxide , which

11970-416: The subsequent 5-cent pieces. This alloy proportion is not ferromagnetic . The US nickel coin contains 0.04 ounces (1.1 g) of nickel, which at the April 2007 price was worth 6.5 cents, along with 3.75 grams of copper worth about 3 cents, with a total metal value of more than 9 cents. Since the face value of a nickel is 5 cents, this made it an attractive target for melting by people wanting to sell

12084-496: The synthetically produced transuranic elements, available samples have been too small to determine crystal structures. Chemical elements may also be categorized by their origin on Earth, with the first 94 considered naturally occurring, while those with atomic numbers beyond 94 have only been produced artificially via human-made nuclear reactions. Of the 94 naturally occurring elements, 83 are considered primordial and either stable or weakly radioactive. The longest-lived isotopes of

12198-955: The table to illustrate recurring trends in the properties of the elements. The layout of the table has been refined and extended over time as new elements have been discovered and new theoretical models have been developed to explain chemical behavior. Use of the periodic table is now ubiquitous in chemistry, providing an extremely useful framework to classify, systematize and compare all the many different forms of chemical behavior. The table has also found wide application in physics , geology , biology , materials science , engineering , agriculture , medicine , nutrition , environmental health , and astronomy . Its principles are especially important in chemical engineering . The various chemical elements are formally identified by their unique atomic numbers, their accepted names, and their chemical symbols . The known elements have atomic numbers from 1 to 118, conventionally presented as Arabic numerals . Since

12312-496: The terrestrial age of meteorites and to determine abundances of extraterrestrial dust in ice and sediment . Nickel-78, with a half-life of 110 milliseconds, is believed an important isotope in supernova nucleosynthesis of elements heavier than iron. Ni, discovered in 1999, is the most proton-rich heavy element isotope known. With 28 protons and 20 neutrons , Ni is " doubly magic ", as is Ni with 28 protons and 50 neutrons. Both are therefore unusually stable for nuclei with so large

12426-558: The time) during non-war years from 1922 to 1981; the metal content made these coins magnetic. During the war years 1942–1945, most or all nickel was removed from Canadian and US coins to save it for making armor. Canada used 99.9% nickel from 1968 in its higher-value coins until 2000. Coins of nearly pure nickel were first used in 1881 in Switzerland. Birmingham forged nickel coins in c.  1833 for trading in Malaysia. In

12540-561: The universe at large, in the spectra of stars and also supernovae, where short-lived radioactive elements are newly being made. The first 94 elements have been detected directly on Earth as primordial nuclides present from the formation of the Solar System , or as naturally occurring fission or transmutation products of uranium and thorium. The remaining 24 heavier elements, not found today either on Earth or in astronomical spectra, have been produced artificially: all are radioactive, with short half-lives; if any of these elements were present at

12654-528: The work of Dmitri Mendeleev , a Russian chemist who published the first recognizable periodic table in 1869. This table organizes the elements by increasing atomic number into rows (" periods ") in which the columns (" groups ") share recurring ("periodic") physical and chemical properties . The periodic table summarizes various properties of the elements, allowing chemists to derive relationships between them and to make predictions about elements not yet discovered, and potential new compounds. By November 2016,

12768-447: Was also used in an absolute sense, as a molar volume divided by Avogadro constant . Such a volume is different for different crystalline forms even of the same compound, but physicists used it for rough, order-of-magnitude estimates of the atomic size, getting 10 –10 cm for copper. The earliest estimates of the atomic size was made by opticians in the 1830s, particularly Cauchy , who developed models of light dispersion assuming

12882-462: Was first isolated and classified as an element in 1751 by Axel Fredrik Cronstedt , who initially mistook the ore for a copper mineral , in the cobalt mines of Los, Hälsingland, Sweden . The element's name comes from a mischievous sprite of German miner mythology, Nickel (similar to Old Nick ). Nickel minerals can be green, like copper ores, and were known as kupfernickel – Nickel's copper – because they produced no copper. Although most nickel in

12996-428: Was patented by Ludwig Mond and has been in industrial use since before the beginning of the 20th century. In this process, nickel is treated with carbon monoxide in the presence of a sulfur catalyst at around 40–80 °C to form nickel carbonyl . In a similar reaction with iron, iron pentacarbonyl can form, though this reaction is slow. If necessary, the nickel may be separated by distillation. Dicobalt octacarbonyl

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