Nickel is the chemical element with symbol Ni and atomic number 28. It is a hard, silvery transition metal that resists corrosion and remains useful at high temperatures. Nickel is essential to stainless steel, superalloys, electroplating, catalysts and several battery technologies.
Nickel quick facts
| Property | Value |
| Symbol | Ni |
| Atomic number | 28 |
| Relative atomic mass | 58.693 |
| Group | 10 |
| Period | 4 |
| Block | d-block |
| Density | 8.90 g/cm³ |
| Melting point | 1455°C |
| Boiling point | 2913°C |
| Electron configuration | [Ar] 3d⁸ 4s² |
| Common oxidation state | +2 |
| CAS number | 7440-02-0 |
| Main natural isotope | ⁵⁸Ni |
Position and electron configuration
Nickel is in group 10, period 4 and the d-block. Its electron configuration is commonly written [Ar] 3d⁸ 4s². Nickel most often forms compounds in the +2 oxidation state, although other states occur in coordination and organometallic chemistry.
See the complete CleverlySmart periodic table.
Physical and magnetic properties
Nickel is strong, ductile, malleable and resistant to oxidation and corrosion. It is ferromagnetic at room temperature. Nickel’s corrosion resistance and high-temperature performance become especially valuable when it is combined with chromium, iron, cobalt or other alloying elements.
Important nickel compounds
- Nickel(II) oxide (NiO): used in ceramics, catalysts, batteries and materials research.
- Nickel sulfate: important in electroplating and battery-material production.
- Nickel carbonyl, Ni(CO)₄: a volatile, extremely toxic compound historically important in nickel purification.
- Nickel hydroxides and oxyhydroxides: important electrochemically active materials in rechargeable batteries.
Occurrence and production
Nickel occurs in sulfide ores and laterite deposits. Major ore minerals include pentlandite, while lateritic ores contain nickel dispersed through iron-rich weathered rocks. Production routes depend on ore type and can involve concentration, smelting, pressure leaching, solvent extraction and electrorefining.
Uses of nickel
- Stainless steel: the largest application; nickel improves toughness, formability and corrosion resistance in many grades.
- Superalloys: nickel-based alloys retain mechanical strength and oxidation resistance at very high temperatures, making them crucial in jet engines and gas turbines.
- Batteries: nickel is used in nickel-metal hydride cells and in several lithium-ion cathode chemistries.
- Electroplating: nickel coatings improve appearance, wear resistance and corrosion protection.
- Catalysis: finely divided nickel and nickel compounds catalyse hydrogenation and other chemical reactions.
- Coins and engineering alloys: nickel improves hardness and durability.
Nickel isotopes
Natural nickel contains five stable isotopes: ⁵⁸Ni, ⁶⁰Ni, ⁶¹Ni, ⁶²Ni and ⁶⁴Ni. Nickel-58 is the most abundant. Nickel-62 is notable for its exceptionally high nuclear binding energy per nucleon.
For broader isotope information, see the CleverlySmart isotope table.
Biological role and safety
Nickel is essential for some microorganisms and plants because it occurs in certain enzymes, but no clearly established essential dietary requirement exists for humans. Nickel is a common contact allergen; jewellery, fasteners and other nickel-releasing objects can trigger allergic dermatitis in sensitised people.
Some nickel compounds and occupational nickel exposures are carcinogenic, so refining, welding and powder-handling operations require appropriate exposure controls. Nickel carbonyl is acutely toxic and demands specialised handling.
History and name
Swedish chemist Axel Fredrik Cronstedt identified nickel as a new element in 1751 while studying an ore miners called kupfernickel, roughly meaning “devil’s copper,” because it resembled copper ore but did not yield copper as expected.
Frequently asked questions
Is nickel magnetic?
Yes. Nickel is ferromagnetic at room temperature.
Why is nickel used in stainless steel?
Nickel can improve toughness, ductility, formability and corrosion resistance while stabilising useful crystal structures in many stainless-steel grades.
Nickel in stainless steel and high-temperature alloys
Nickel improves corrosion resistance, toughness and high-temperature strength. Austenitic stainless steels often contain nickel because it stabilises the face-centred cubic austenite phase, helping the alloy remain ductile over a wide temperature range.
Nickel-based superalloys are crucial in gas turbines and jet engines. Their carefully engineered microstructures retain strength under sustained heat and mechanical stress, while chromium and aluminium additions help resist oxidation.
Catalysis, batteries and nickel carbonyl
Finely divided nickel is an important hydrogenation catalyst, including in food and chemical processing. Nickel also appears in rechargeable batteries such as nickel-metal-hydride cells and in several lithium-ion cathode chemistries.
One unusual compound is nickel carbonyl, Ni(CO)₄, a volatile and highly toxic liquid. It is used in the Mond process for refining nickel, illustrating how metal carbonyl chemistry can enable purification while creating serious handling hazards.
Frequently asked questions
Why can nickel cause skin reactions?
Nickel ions can trigger allergic contact dermatitis in sensitised people, which is why nickel release from jewellery and consumer products is regulated in many places.
Is nickel magnetic?
Metallic nickel is ferromagnetic at room temperature, although alloying and temperature can change its magnetic behaviour.
