# Nickel

By [FLIGMATA](https://paragraph.com/@fligmata) · 2023-05-30

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**Nickel** is a [chemical element](https://en.wikipedia.org/wiki/Chemical_element) with [symbol](https://en.wikipedia.org/wiki/Chemical_symbol) **Ni** and [atomic number](https://en.wikipedia.org/wiki/Atomic_number) 28. It is a silvery-white lustrous [metal](https://en.wikipedia.org/wiki/Metal) with a slight golden tinge. Nickel is a hard and [ductile](https://en.wikipedia.org/wiki/Ductility) [transition metal](https://en.wikipedia.org/wiki/Transition_metal). Pure nickel is chemically reactive but large pieces are slow to react with air under [standard conditions](https://en.wikipedia.org/wiki/Standard_conditions_for_temperature_and_pressure) because a [passivation layer](https://en.wikipedia.org/wiki/Passivation_\(chemistry\)) of [nickel oxide](https://en.wikipedia.org/wiki/Nickel\(II\)_oxide) forms on the surface that prevents further corrosion. Even so, pure [native](https://en.wikipedia.org/wiki/Native_metal) nickel is found in Earth's crust only in tiny amounts, usually in [ultramafic rocks](https://en.wikipedia.org/wiki/Ultramafic_rock),[\[5\]](https://en.wikipedia.org/wiki/Nickel#cite_note-5)[\[6\]](https://en.wikipedia.org/wiki/Nickel#cite_note-6) and in the interiors of larger [nickel–iron meteorites](https://en.wikipedia.org/wiki/Iron_meteorite) that were not exposed to oxygen when outside Earth's atmosphere.

[Meteoric nickel](https://en.wikipedia.org/wiki/Meteoric_iron) is found in combination with [iron](https://en.wikipedia.org/wiki/Iron), a reflection of the origin of those elements as major end products of [supernova nucleosynthesis](https://en.wikipedia.org/wiki/Supernova_nucleosynthesis). An iron–nickel mixture is thought to compose [Earth's outer](https://en.wikipedia.org/wiki/Earth%27s_outer_core) and [inner cores](https://en.wikipedia.org/wiki/Earth%27s_inner_core).[\[7\]](https://en.wikipedia.org/wiki/Nickel#cite_note-7)

Use of nickel (as natural [meteoric](https://en.wikipedia.org/wiki/Meteoric_iron) nickel–iron alloy) has been traced as far back as 3500 BCE. Nickel was first isolated and classified as an element in 1751 by [Axel Fredrik Cronstedt](https://en.wikipedia.org/wiki/Axel_Fredrik_Cronstedt), who initially mistook the [ore](https://en.wikipedia.org/wiki/Ore) for a [copper](https://en.wikipedia.org/wiki/Copper) [mineral](https://en.wikipedia.org/wiki/Mineral), in the cobalt mines of [Los, Hälsingland, Sweden](https://en.wikipedia.org/wiki/Los,_Sweden). The element's name comes from a mischievous sprite of German miner mythology, Nickel (similar to [Old Nick](https://en.wikipedia.org/wiki/Devil_in_Christianity#Christian_tradition)), who personified the fact that copper-nickel ores resisted refinement into copper. An economically important source of nickel is the [iron](https://en.wikipedia.org/wiki/Iron) ore [limonite](https://en.wikipedia.org/wiki/Limonite), which is often 1–2% nickel. Other important nickel ore minerals include [pentlandite](https://en.wikipedia.org/wiki/Pentlandite) and a mix of Ni-rich natural silicates known as [garnierite](https://en.wikipedia.org/wiki/Garnierite). Major production sites include the [Sudbury region](https://en.wikipedia.org/wiki/Sudbury_Basin), [Canada](https://en.wikipedia.org/wiki/Canada) (which is thought to be of [meteoric](https://en.wikipedia.org/wiki/Meteorite) origin), [New Caledonia](https://en.wikipedia.org/wiki/New_Caledonia) in the [Pacific](https://en.wikipedia.org/wiki/Pacific_Ocean), and [Norilsk](https://en.wikipedia.org/wiki/Norilsk), [Russia](https://en.wikipedia.org/wiki/Russia).

Nickel is one of four elements (the others are [iron](https://en.wikipedia.org/wiki/Iron), [cobalt](https://en.wikipedia.org/wiki/Cobalt), and [gadolinium](https://en.wikipedia.org/wiki/Gadolinium))[\[8\]](https://en.wikipedia.org/wiki/Nickel#cite_note-CoeySkumryev1999-8) that are [ferromagnetic](https://en.wikipedia.org/wiki/Ferromagnetic) at about room temperature. [Alnico](https://en.wikipedia.org/wiki/Alnico) permanent [magnets](https://en.wikipedia.org/wiki/Magnets) based partly on nickel are of intermediate strength between iron-based permanent magnets and [rare-earth magnets](https://en.wikipedia.org/wiki/Rare-earth_magnet). The metal is used chiefly in [alloys](https://en.wikipedia.org/wiki/Alloy) and corrosion-resistant plating. About 68% of world production is used in [stainless steel](https://en.wikipedia.org/wiki/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,[\[9\]](https://en.wikipedia.org/wiki/Nickel#cite_note-Nickel_Use_In_Society-9) including those in [electric vehicles](https://en.wikipedia.org/wiki/Electric_vehicle) (EVs).[\[10\]](https://en.wikipedia.org/wiki/Nickel#cite_note-10) Nickel is widely used in [coins](https://en.wikipedia.org/wiki/Coins), though nickel-plated objects sometimes provoke [nickel allergy](https://en.wikipedia.org/wiki/Nickel_allergy). As a compound, nickel has a number of niche chemical manufacturing uses, such as a [catalyst for hydrogenation](https://en.wikipedia.org/wiki/Raney_nickel), [cathodes](https://en.wikipedia.org/wiki/Cathode) for rechargeable batteries, pigments and metal surface treatments.[\[11\]](https://en.wikipedia.org/wiki/Nickel#cite_note-11) Nickel is an essential nutrient for some microorganisms and plants that have [enzymes](https://en.wikipedia.org/wiki/Enzymes) with nickel as an [active site](https://en.wikipedia.org/wiki/Active_site).[\[12\]](https://en.wikipedia.org/wiki/Nickel#cite_note-12)

Properties
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### Atomic and physical properties

[Electron micrograph](https://en.wikipedia.org/wiki/Transmission_electron_microscopy) of a Ni nanocrystal inside a single wall [carbon nanotube](https://en.wikipedia.org/wiki/Carbon_nanotube); scale bar 5 nm[\[13\]](https://en.wikipedia.org/wiki/Nickel#cite_note-13)

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](https://en.wikipedia.org/wiki/Ferromagnetism) at or near room temperature; the others are iron, [cobalt](https://en.wikipedia.org/wiki/Cobalt) and [gadolinium](https://en.wikipedia.org/wiki/Gadolinium). Its [Curie temperature](https://en.wikipedia.org/wiki/Curie_temperature) is 355 °C (671 °F), meaning that bulk nickel is non-magnetic above this temperature.[\[14\]](https://en.wikipedia.org/wiki/Nickel#cite_note-14)[\[8\]](https://en.wikipedia.org/wiki/Nickel#cite_note-CoeySkumryev1999-8) The unit cell of nickel is a [face-centered cube](https://en.wikipedia.org/wiki/Cubic_crystal_system) with the lattice parameter of 0.352 nm, giving an [atomic radius](https://en.wikipedia.org/wiki/Atomic_radius) of 0.124 nm. This crystal structure is stable to pressures of at least 70 GPa. Nickel is hard, malleable and [ductile](https://en.wikipedia.org/wiki/Ductility), and has a relatively high [electrical](https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity) and [thermal conductivity](https://en.wikipedia.org/wiki/Thermal_conductivity) for transition metals.[\[15\]](https://en.wikipedia.org/wiki/Nickel#cite_note-crc-15) The high [compressive strength](https://en.wikipedia.org/wiki/Compressive_strength) of 34 GPa, predicted for ideal crystals, is never obtained in the real bulk material due to formation and movement of [dislocations](https://en.wikipedia.org/wiki/Dislocation). However, it has been reached in Ni [nanoparticles](https://en.wikipedia.org/wiki/Nanoparticle).[\[16\]](https://en.wikipedia.org/wiki/Nickel#cite_note-16)

#### Electron configuration dispute

Nickel has two atomic [electron configurations](https://en.wikipedia.org/wiki/Electron_configuration), \[Ar\] 3d8 4s2 and \[Ar\] 3d9 4s1, which are very close in energy; \[Ar\] denotes the complete [argon](https://en.wikipedia.org/wiki/Argon) core structure. There is some disagreement on which configuration has the lower energy.[\[17\]](https://en.wikipedia.org/wiki/Nickel#cite_note-Scerri-17) Chemistry textbooks quote nickel's electron configuration as \[Ar\] 4s2 3d8,[\[18\]](https://en.wikipedia.org/wiki/Nickel#cite_note-18) also written \[Ar\] 3d8 4s2.[\[19\]](https://en.wikipedia.org/wiki/Nickel#cite_note-19) This configuration agrees with the [Madelung energy ordering rule](https://en.wikipedia.org/wiki/Madelung_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 is a 3d8 4s2 energy level, specifically the 3d8(3F) 4s2 3F, _J_ = 4 level.[\[20\]](https://en.wikipedia.org/wiki/Nickel#cite_note-JPCRD-20)[\[21\]](https://en.wikipedia.org/wiki/Nickel#cite_note-NIST-21)

However, each of these two configurations splits into several energy levels due to [fine structure](https://en.wikipedia.org/wiki/Fine_structure),[\[20\]](https://en.wikipedia.org/wiki/Nickel#cite_note-JPCRD-20)[\[21\]](https://en.wikipedia.org/wiki/Nickel#cite_note-NIST-21) and the two sets of energy levels overlap. The average energy of states with \[Ar\] 3d9 4s1 is actually lower than the average energy of states with \[Ar\] 3d8 4s2. Therefore, the research literature on atomic calculations quotes the ground state configuration as \[Ar\] 3d9 4s1.[\[17\]](https://en.wikipedia.org/wiki/Nickel#cite_note-Scerri-17)

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*Originally published on [FLIGMATA](https://paragraph.com/@fligmata/nickel)*