28 Ni 58.693

Nickel

Transition metal Niccolum solid

[Ar] 3d⁸ 4s² · 2 · 8 · 16 · 2

← Co Cobalt Cu Copper →

A ferromagnetic metal resistant to corrosion and to alkalis. Nickel makes steel stainless alongside chromium, keeps it tough at cryogenic temperatures, and shares Earth's core with iron.

3D model

Bohr model: nucleus and electron shells from the real configuration. Valence electrons are highlighted.

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Atomic properties

Atomic number: 28
Atomic mass: 58.693 а.е.м.
Electron configuration: [Ar] 3d⁸ 4s²
Electrons per shell: 2 · 8 · 16 · 2
Block: d-block
Group: Nickel group
Period: 4
Electronegativity (Pauling): 1.91
Electronegativity (Allen): 1.88
Atomic radius: 149 pm
Covalent radius: 124 pm
Van der Waals radius: 163 pm
Ionisation energy 1: 737.1 kJ/mol
Ionisation energy 2: 1 753 kJ/mol
Ionisation energy 3: 3 395 kJ/mol
Ionisation energy 4: 5 300 kJ/mol
Ionisation energy 5: 7 339 kJ/mol
Electron affinity: 112 kJ/mol
Common oxidation states: +2
Oxidation states: -2, -1, +1, +2, +3, +4

Physical properties

State at 25 °C: solid
Density: 8.908 g/cm³
Melting point: 1 728 K · 1 454.9 °C
Boiling point: 3 003 K · 2 729.9 °C
Speed of sound: 4 900 m/s

Thermal properties

Heat of fusion: 17.48 kJ/mol
Heat of vaporisation: 379 kJ/mol
Specific heat capacity: 0.444 J/(g·K)
Thermal conductivity: 90.9 W/(m·K)

Mechanical properties

Young's modulus: 200 GPa
Shear modulus: 76 GPa
Bulk modulus: 180 GPa
Poisson ratio: 0.31
Mohs hardness: 4
Brinell hardness: 700 MPa

Electrical and magnetic properties

Electrical resistivity: 69.3 nΩ·m
Magnetic ordering: ferromagnetic
Curie point: 627 K
Néel point: no data
Superconducting point: no data

Crystal structure

Crystal structure: face-centred cubic (fcc)
Lattice constants: a = 352.4 pm

Abundance

In the crust: 84 mg/kg
In the ocean: 0.00056 mg/L
In the universe: 60 000 mg/kg
In the human body: 0.015 mg/kg

Isotopes

Isotope	Abundance	Half-life	Decay mode
⁵⁸Ni	68.077 %	stable	—
⁶⁰Ni	26.223 %	stable	—
⁶¹Ni	1.14 %	stable	—
⁶²Ni	3.635 %	stable	—
⁶⁴Ni	0.926 %	stable	—

Nickel-62 has the highest binding energy per nucleon of any nuclide — slightly above iron-56, even though it is iron that accumulates in stars.

Discovery

Year of discovery: 1751
Discovered by: Axel Fredrik Cronstedt
Where: Sweden
Origin of the name: from German Kupfernickel (Old Nick's copper), an ore that gave no copper

History

Saxon miners called a useless red ore Kupfernickel, Old Nick's copper, because it looked like copper ore and gave none. Axel Cronstedt isolated a new metal from it in 1751 and left the goblin in the name.

Where it occurs

84 mg/kg of the crust, but far more in Earth's core. Two ore types: sulfides (Norilsk, Sudbury) and laterites (Indonesia, the Philippines).

How it is produced

Sulfide ores are smelted and refined electrolytically or by the Mond carbonyl process. Laterites are treated by pressure hydrometallurgy.

Role in living things

Some bacteria and plants require nickel, which sits in urease. For humans no requirement is established, but nickel is the commonest contact allergen: roughly one person in ten reacts to it.

Safety

Contact dermatitis from jewellery and buckles is widespread, which is why the EU limits nickel release from consumer goods. Nickel carbonyl, Ni(CO)₄, is extraordinarily poisonous, and nickel sulfide dust is carcinogenic.

Uses

Stainless steel — about two thirds of all nickel
Lithium-ion cathodes, where nickel's share rises as cobalt is designed out
Superalloys for jet engine turbines
Electroplating and coinage
Catalyst for hydrogenating fats

Curiosities

Nickel-62, not iron-56, formally tops the binding-energy table; the common belief has it the other way round.
The Mond carbonyl process purifies nickel to 99.99 % by nothing more than heating and cooling.
Meteoritic iron always contains nickel, which is how it is told from terrestrial iron.
The US five-cent coin is called a nickel although only a quarter of it is nickel.