Nickel was first isolated and classified as a chemical element in 1751 by Axel Fredrik Cronstedt, who initially mistook its orefor a copper mineral.

Nickel is a chemical element with symbol Ni and atomic number 28.

 An iron–nickel mixture is thought to compose Earth's inner core.

PHYSICAL PROPERTIES

Phase solid

Melting point 1728 K  (1455 °C, 2651 °F)

Boiling point 3003 K (2730 °C, 4946 °F)

Density near r.t. 8.908 g·cm−3

when liquid, at m.p. 7.81 g·cm−3

Heat of fusion 17.48 kJ·mol−1

Heat of vaporization 379 kJ·mol−1

Molar heat capacity 26.07 J·mol−1·K−1

The nickel atom has two electron configurations, [Ar] 3d8 4s2 and [Ar] 3d9 4s1, which are very close in energy – the symbol [Ar] refers to the argon-like core structure.

Naturally occurring nickel is composed of five stable isotopes; 58Ni, 60Ni, 61Ni, 62Ni and 64Ni with 58Ni being the most abundant (68.077% natural abundance).

MiscellaneaCrystal structure face-centered cubic (fcc)Speed of soundthin rod 4900 m·s−1 (at r.t.)Thermal expansion 13.4 µm·m−1·K−1 (at 25 °C)Thermal conductivity 90.9 W·m−1·K−1

Electrical resistivity 69.3 nΩ·m (at 20 °C)Magnetic ordering ferromagneticYoung's modulus 200 GPaShear modulus 76 GPaBulk modulus 180 GPaPoisson ratio 0.31Mohs hardness 4.0Vickers hardness 638 MPaBrinell hardness 667–1600 MPa

Purification of nickel oxides to obtain the purest metal is performed via the Mond process, which increases the nickel concentrate to greater than 99.99% purity.

Nickel is used in many specific and recognizable industrial and consumer products, including stainless steel, alnico magnets, coinage, rechargeable batteries, electric guitar strings, microphone capsules, and special alloys

APPLICATIONS:

The plant enzyme urease (an enzyme that assists in the hydrolysis of urea) contains nickel.

Nickel can have an impact on human health through infectious diseases arising from nickel-dependent bacteria.[71] Nickel released from Siberian Traps volcanic eruptions (site of the modern city of Norilsk) is suspected of having had a significant impact on the role played by Methanosarcina, a genus of euryarchaeote archaea that produced methane during the biggest extinction event on record.

Biological role

Nickel carbonyl, [Ni(CO)4], is an extremely toxic gas.

Sensitivity to nickel may also be present in patients with pompholyx. 

Nickel is an important cause of contact allergy, partly due to its use in jewellery intended for pierced ears.

TOXICITY:

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