Nickel
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile.
Identity
- Atomic mass
- 58.693 u
- Category
- Transition metals
- Group
- 10
- Period
- 4
- Block
- d
- Oxidation States
- +2, +3
- Phase (25 °C)
- Solid
- Appearance
- lustrous, metallic, and silver with a gold tinge
Electronic Structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d8
- Short configuration
- [Ar] 3d8 4s2
- Electrons per shell
- 2, 8, 16, 2
- Electronegativity (Pauling)
- 1.91
- Electron affinity
- 112 kJ/mol
- 1st ionization energy
- 737 kJ/mol
- Ionization energies
- 737 · 1753 · 3395 · 5300 · 7339… kJ/mol
Physical properties
- Melting point
- 1454.8 °C (1728 K)
- Boiling point
- 2729.8 °C (3003 K)
- Density
- 8.908 g/cm³
- Molar heat capacity
- 26.1 J/(mol·K)
Chemical behavior of nickel
Nickel is a group 10 transition metal with symbol Ni and atomic number 28. It is a hard silvery metal with a slight golden tinge, corrosion resistant and ferromagnetic. Its most stable oxidation state is +2, with +3 and +4 in specific compounds. It is one of the most important metals for stainless steels, alloys and modern batteries.
Reactivity
Ni + 2 Cl2 -> NiCl4
Nickel reacts with chlorine to form nickel(IV) chloride, a bluish-green solid that is the most stable compound.
Ni + H2SO4 (acid), -> NiSO4 + H2
Nickel reacts with dilute sulfuric acid, releasing hydrogen and forming nickel(II) sulfate.
Notable compounds
| Compound | Formula | Use or importance |
|---|---|---|
| Nickel(II) chloride | NiCl2 | Green solid; getter and catalyst precursor |
| Nickel(II) oxide | NiO | Green solid; getter precursor and used in pigments |
| Nickel(II) sulfate | NiSO4 | Green solid; getter precursor and used in electrodes |
Electron shell distribution
View in the atom builderIsotopes
Natural nickel combines five stable isotopes: nickel-58 (68.1 %), nickel-60 (26.2 %), nickel-62 (3.6 %), nickel-61 (1.1 %) and nickel-64 (0.9 %). Nickel-58 is the most abundant. Nickel-59 is a long-lived radioisotope (half-life 76,000 years) of interest in nuclear science.
Occurrence and production
Nickel is among the ten most abundant elements in the crust (about 80 ppm) and a major component of the Earth core. It appears in Pentlandite, garnierite and laterites. Main producers include Indonesia, the Philippines, Russia, Canada and Australia. Much output comes as a co-product of copper and platinum refining.
History and origin of the name
Nickel was isolated in 1751 by Axel Fredrik Cronstedt in Sweden from an ore miners called kupfernickel (false copper). Its name comes from Nickel, a sprite blamed for the useless ore. It became key for stainless steels, coinage and modern metallurgy.
Applications and relevance of nickel
Uses of the element
About two thirds goes to stainless steels, plus superalloys for jet turbines, nickel plating, coinage and lithium-ion and NiMH batteries. Nickel superalloys keep strength where many metals weaken at high temperature.
Uses of its compounds
Salts feed electroplating and battery cathodes; Raney nickel and supported nickel catalyze hydrogenation of oils and fuels; oxides color glass and ceramics.
Health, safety and environment
Biological role
Some organisms need traces of nickel as an enzyme cofactor. Humans have no established requirement; diet provides small amounts. High chronic doses can affect lungs and gut, and soluble salts are the main concern rather than compact metal.
Safety
Metal has low toxicity, but inorganic compounds and dust can irritate skin, eyes and airways. Nickel contact allergy is common: prolonged skin contact with releasing objects can trigger dermatitis. Rules limit nickel release in jewelry and wearables.
Environment
Nickel is persistent and mining, smelting and plating effluents must be controlled. Recycling stainless steel and batteries recovers much of the metal and cuts the need for primary extraction.
Frequently asked questions about Nickel
Why is nickel essential for stainless steel?
Nickel stabilizes the austenitic structure that makes many stainless steels tough, ductile and corrosion resistant. Typical 18/8 steels combine chromium for the passive layer with nickel for formability. Without enough nickel, some grades lose weldability or cryogenic toughness.
Why is nickel used to plate metal objects?
Nickel plating deposits a uniform layer that improves finish and, in the right conditions, wear and corrosion resistance. It coats industrial parts, taps and decor, and can underlie chromium. Thickness and bath chemistry set the result; prolonged skin contact must consider allergy.
How is nickel used as an industrial catalyst?
Nickel catalyzes hydrogenation, adding hydrogen to molecules such as vegetable oils, plus fuel and chemical processes. Its surface activates reactants but can be poisoned by impurities, so formulation and maintenance matter.
Why can nickel cause contact allergy?
In sensitive people, ions released by objects in prolonged skin contact trigger allergic contact dermatitis. Risk depends on release rate, contact time and individual sensitivity. Standards limit nickel release in products for direct prolonged skin contact.
Why is nickel used in rechargeable batteries?
Nickel-rich cathodes store much energy per kilogram, giving EVs longer range. But design must balance energy density with thermal stability, lifetime and cost. Hence families with nickel and without it (like lithium-iron phosphate) coexist for different uses.
What makes nickel alloys useful in jet engines?
Nickel superalloys keep high mechanical strength at temperatures where many metals soften. With chromium, cobalt and aluminium they resist heat, stress and oxidation in turbine blades and power equipment. Composition and microstructure must be tightly controlled.
Why do some coins contain nickel?
Nickel adds hardness, wear resistance and a uniform metallic look, alone or with copper. Mints balance cost, durability, striking ease and the magnetic signature that vending systems expect. Not all silvery coins contain it.
Main sources consulted: PubChem, Royal Society of Chemistry, NIST, IUPAC. Last revision: November 2026.