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This article is about the element nickel. See also nickel (U.S. coin) and nickel (Canadian coin).
Name, Symbol, Number nickel, Ni, 28
Chemical series transition metals
Group, Period, Block 10 , 4, d
Density, Hardness 8908 kg/m³, 4.0
Appearance lustrous, metallic
Atomic properties
Atomic weight 58.6934 amu
Atomic radius (calc.) 135 (149) pm
Covalent radius 121 pm
van der Waals radius 163 pm
Electron configuration [Ar]3d84s2
e- 's per energy level 2, 8, 16, 2
Oxidation states (Oxide) 2,3 (mildly basic)
Crystal structure cubic, face-centered
Physical properties
State of matter solid (ferromagnetic)
Melting point 1728 K (2651 F)
Boiling point 3186 K (5275 F)
Molar volume 6.59 ×10-6 m³/mol
Heat of vaporization 370.4 kJ/mol
Heat of fusion 17.47 kJ/mol
Vapor pressure 237 Pa at 1726 K
Velocity of sound 4970 m/s at 293.15 K
Electronegativity 1.91 (Pauling scale)
Specific heat capacity 440 J/(kgK)
Electrical conductivity 14.3 106/ (mohm)
Thermal conductivity 90.7 W/(mK)
1st ionization potential 737.1 kJ/mol
2nd ionization potential 1753 kJ/mol
3rd ionization potential 3395 kJ/mol
4th ionization potential 5300 kJ/mol
Most stable isotopes
iso NA half-life DM DE MeV DP
56Ni {syn.} 6.077 days ε 2.136 56Co
58Ni 68.077% Ni is stable with 30 neutrons
59Ni {syn.} 76000 years ε 1.072 59Co
60Ni 26.233% Ni is stable with 32 neutrons
61Ni 1.14% Ni is stable with 33 neutrons
62Ni 3.634% Ni is stable with 34 neutrons
63Ni {syn.} 100.1 years β- 2.137 63Cu
64Ni 0.926% Ni is stable with 36 neutrons
SI units & STP are used except where noted.

Nickel is a metallic chemical element in the periodic table that has the symbol Ni and atomic number 28.


Notable characteristics

Nickel is silvery white metal that takes on a high polish. It belongs to the iron group, and is hard, malleable, and ductile. It occurs combined with sulfur in millerite, with arsenic in the mineral niccolite, and with arsenic and sulfur in nickel glance .

On account of its permanence in air and inertness to oxidation, it is used in the smaller coins, for plating iron, brass, etc., for chemical apparatus, and in certain alloys, as German silver. It is magnetic, and is very frequently accompanied by cobalt, both being found in meteoric iron. It is chiefly valuable for the alloys it forms.

Nickel is one of the five ferromagnetic elements. Because of the precise alloy used, the US "nickel" coin is not ferromagnetic, while the Canadian coin of the same name is up to and including the year 1958.

The most common oxidation state of nickel is +2, though 0, +1 and +3 Ni complexes are observed.


About 65% of the nickel consumed in the Western World is used to make austenitic stainless steel. Another 12% goes into superalloys. The remaining 23% of consumption is divided between alloy steels, rechargeable batteries, catalysts and other chemicals, coinage, foundry products, and plating.

Applications include:


Nickel use is ancient, and can be traced back as far as 3500 BC. Bronzes from what is now Syria had a nickel content of up to two percent. Further, there are Chinese manuscripts suggesting that "white copper" (e.g. baitung) was used in the Orient between 1400 and 1700 BC. However, because the ores of nickel were easily mistaken for ores of silver, any understanding of this metal and its use dates to more contemporary times.

Minerals containing nickel (e.g. kupfernickel, or false copper) were of value for coloring glass green. In 1751, Baron Axel Frederik Cronstedt was attempting to extract copper from kupfernickel (now called niccolite), and obtained instead a white metal that he called nickel.

The first nickel coin of the pure metal was made in 1881.

Biological role

Many but not all hydrogenases contain nickel in addition to iron-sulfur clusters. Nickel centers are a common element in those hydrogenases whose function is to oxidize rather than evolve hydrogen. The nickel center appears to undergo changes in oxidation state, and evidence has been presented that the nickel center might be the active site of these enzymes.

A nickel-tetrapyrrole coenzyme, Co-F430, is present in the methyl CoM reductase and in methanogenic bacteria. The tetrapyrrole is intermediate in structure between porphyrin and corrin. Changes in redox state, as well as changes in nickel coordination, have recently been observed.

There is also a nickel-containing carbon monoxide dehydrogenase. Little is known about the structure of the nickel site.


The bulk of the nickel mined comes from two types of ore deposits. The first are laterites where the principal ore minerals are nickeliferous limonite: (Fe,Ni)O(OH) and garnierite (a hydrous nickel silicate): (Ni,Mg)3Si2O5(OH). The second are magmatic sulfide deposits where the principal ore mineral is pentlandite: (Ni,Fe)9S8.

In terms of supply, the Sudbury region of Ontario, Canada, produces about 30 percent of the world's supply of nickel. The Sudbury deposit is located in an area with evidence of a massive meteorite impact event early in the geologic history of Earth. Other deposits are found elsewhere in Canada, as well as in Russia, New Caledonia, Australia, Cuba, and Indonesia. The deposits in tropical areas are typically laterites which are produced by the intense weathering of ultramafic igneous rocks and the resulting secondary concentration of nickel bearing oxide and silicate minerals.

Based on geophysical evidence, most of the nickel on Earth is postulated to be concentrated in the Earth's core.

Extraction and Purification

Nickel can be recovered using extractive metallurgy. Oxy-hydroxide ores are treated using hydrometallurgy, and from sulfide mineral concentrates using pyrometallurgical or hydrometallurgical techniques. Sulfide mineral concentrates are produced by applying the froth flotation process.

Nickel is extracted from its ores by conventional roasting and reduction processes which yield a metal of >95% purity. Final purification to >99.99% purity is performed by reacting Nickel and carbon monoxide to form Nickel carbonyl. This gas is passed into a large chamber at a higher temperature in which tens of thousands of nickel spheres are maintained in constant motion. The Nickel carbonyl decomposes depositing pure nickel onto the nickel spheres. The resultant carbon monoxide is re-circulated through the process.


  • Kamacite is a naturally occurring alloy of iron and nickel, usually in the proportion of 90:10 to 95:5 although impurities such as cobalt or carbon may be present. Kamacite occurs in nickel-iron meteorites.


Naturally occurring nickel is composed of 5 stable isotopes; 58-Ni, 60-Ni, 61-Ni, 62-Ni and 64-Ni with 58-Ni being the most abundant (68.077% natural abundance). 18 radioisotopes have been characterized with the most stable being 59-Ni with a half-life of 76,000 years, 63-Ni with a half-life of 100.1 years, and 56-Ni with a half-life of 6.077 days. All of the remaining radioactive isotopes have half-lifes that are less than 60 hours and the majority of these have half lifes that are less than 30 seconds. This element also has 1 meta state.

Nickel-56 is produced in large quantities in type Ia supernovae and the shape of the light curve of these supernovae corresponds to the decay of nickel-56 to cobalt-56 and then to iron-56.

Nickel-59 is a long-lived cosmogenic radionuclide with a half-life of 76,000 years. 59Ni has found many applications in isotope geology . 59Ni has been used to date the terrestrial age of meteorites and to determine abundances of extraterrestrial dust in ice and sediment. Nickel-60 is the daughter product of the extinct radionuclide 60Fe (half-life = 1.5 Myr). Because the extinct radionuclide 60Fe had such a long half-life, its persistence in solar_system materials at high enough concentrations may have generated observable variations in the isotopic composition of 60Ni. Therefore, the abundance of 60Ni present in extraterrestrial material may provide insight into the origin of the solar system and its early history.

The isotopes of nickel range in atomic weight from 52 amu (52-Ni) to 74 amu (74-Ni).


Exposure to nickel metal and soluble compounds should not exceed 0.05 mg/cm³ in nickel equivalents per 40-hour work week. Nickel sulfide fume and dust is believed to be carcinogenic, and various other nickel compounds may be as well.

Nickel carbonyl, [Ni(CO)4], is an extremely toxic gas. The toxicity of metal carbonyls is a function of both the toxicity of a metal as well as the carbonyl's ability to give off highly toxic carbon monoxide gas, and this one is no exception. It is explosive in air.

Sensitized individuals may show an allergy to nickel affecting their skin. The amount of nickel which is allowed in products which come into contact with human skin is regulated by the European Union. In 2002 a report in the journal Nature researchers found amounts of nickel being emitted by 1 and 2 euro coins far in excess of those standards. This is believed to be due to a galvanic reaction.


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Last updated: 07-29-2005 21:22:59
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