Nickel

Nickel,  ₂₈Ni

Nickel metal in powdered form
General properties
Name, symbol	Nickel, Ni
Appearance	A silvery metal that resists corrosion even at high temperatures.
Nickel in the periodic table
↑ Ni ↓ Pd Cobalt ← Nickel → Copper
Atomic number	28
Standard atomic weight (Ar)	58.6934(4)
Group, block	, d-block
Period	period 4
Electron configuration	[Ar] 3d8 4s2 or [Ar] 3d9 4s1
per shell	2, 8, 16, 2 or 2, 8, 17, 1
Physical properties
Silvery metallic
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/cm3
when liquid, at	7.81 g/cm3
Heat of fusion	17.48 kJ/mol
Heat of	379 kJ/mol
Molar heat capacity	26.07 J/(mol·K)
pressure
Atomic properties
Oxidation states	4, 3, 2, 1, -1, -2 ​(a mildly basic oxide)
Electronegativity	Pauling scale: 1.91
energies	1st: 737.129 kJ/mol 2nd: 1753.027 kJ/mol 3rd: 3395.32 kJ/mol (more)
Atomic radius	empirical: 124 pm
Covalent radius	124±4 pm
Van der Waals radius	163 pm
Miscellanea
Crystal structure	​Face-centered cubic (fcc)
Speed of sound thin rod	4900 m/s (at )
Thermal expansion	13.4 µm/(m·K) (at 25 °C)
Thermal conductivity	90.9 W/(m·K)
Electrical resistivity	6.93·10-8 Ω·m (at 20 °C)
Magnetic ordering	Ferromagnetic
Young's modulus	200 GPa
Shear modulus	76 GPa
Bulk modulus	180 GPa
Poisson ratio	0.31
Mohs hardness	4.0
Vickers hardness	638 MPa
Brinell hardness	667–1600 MPa
CAS Registry Number	7440-02-0
Discovery and first isolation	Axel Fredrik Cronstedt (1751)

Nickel is a transition metal with the symbol Ni and atomic number 28. It is well-known as a coinage material due to its corrosion resistance, and is often used to plate objects. In solution, it has extensive coordination chemistry, and some interesting redox chemistry which is not commonly seen.

Properties

Physical properties

Nickel is a silvery-white metal that has a slight yellowish tinge. It is one of four elements that is ferromagnetic at or near room temperature (iron, cobalt, and gadolinium being the others). Its Curie temperature is 355 °C, which causes the metal to reversibly become paramagnetic. It is hard yet ductile.

Chemical properties

Much of nickel's chemical resistance owes to its passivation in air. It will also passivate in the presence of fluorine, making it an ideal material for handling and storing the gas. It will dissolve only slowly in hydrochloric and sulfuric acids. In concentrated nitric acid, nickel will not dissolve, but it will dissolve in dilute nitric acid.

Nickel(II) compounds form a hexaaqua complex in water with the formula [Ni(H₂O)₆]²⁺ and coordinate to many different ligands, including chloride, ammonia, and ethylenediamine. These complexes can be hexacoordinate, tetragonal, or square planar, with square planar complexes such as tetrachloronickelate being diamagnetic rather than paramagnetic.

Availability

Nickel is present as the main material (certified 99.9%) in older Canadian nickels, dating from 1922 to 1942, and older Canadian dimes dating from 1969 to 1999. It is also present in US nickels, dimes, quarters and in 1 and 2 euro coins too. However, the majority of the metal is copper, with nickel making up anywhere from 9% to 25% of the coin. Destroying coins is illegal however, and heavy fines exist everywhere for breaking this law.

A good source of nickel is Mu-metal, an alloy containing 77-80% nickel, 16% iron, 5-2% copper and molybdenum. This alloy is commonly encountered in the hard drive magnets brackets, which can be extracted from hard disks. As a bonus, they are also nickel plated. Old submarine cables also contain Mu-metal wiring. Cathode tubes are also a source. Chemical extraction is required to separate the nickel. However, many hobby chemists have discovered that the "Mu metal" brackets commonly found in hard drives do not contain any significant amounts of nickel and instead are made of iron/steel. As such, one will have to check the model of the hard drives they take apart, to find only the ones that are known to use actual Mu metal.

Nickel strips for electroplating can be bought from United Nuclear.

Another good source of nickel metal is the Ni200 wire sold in many electronic cigarette stores, as heating wire. The nickel content is 99%.

Isolation

Nickel metal can be produced very easily by electrowinning in from a nickel salt solution.

Ultrapure Ni metal can be obtained by careful thermal decomposition of nickel carbonyls, in inert atmosphere, which yields very fine and very pure Ni powder. This route is called the Mond process.

Projects

• Nickel plating
• Coordination complexes
• Building a battery
• Make Raney nickel

Handling

Safety

Nickel compounds are known to be carcinogens, and are grouped as class 1. Nickel metal is grouped as class 2B (it is a suspected carcinogen). However, it is not regulated by OSHA.

Some people are allergic to nickel metal and develop an itch or rash when exposed to it (contact dermatitis). If this occurs, wear gloves when handling the metal.

Storage

No special storage is required for bulk nickel. Nickel powder must be stored in closed bottles, away from any ignition source.

Disposal

Nickel and its compounds should be taken to disposal facilities.

References

Relevant Sciencemadness threads

• Separation of a US nickel
• how extrac nickel
• Things to do with Nickel