NICKEL: HISTORY, PROPERTIES, STRUCTURE, USES, RISKS - CHEMISTRY - 2024

The nickel is a transition metal white chemical symbol is Ni. Its hardness is greater than that of iron, in addition to being a good conductor of heat and electricity, and in general, it is considered a metal that is not very reactive and is highly resistant to corrosion. In its pure state, it is silver with golden hues.

In 1751, Axel Fredrik Cronsted, a Swedish chemist, managed to isolate it from a mineral known as Kupfernickel (devil's copper), extracted from a cobalt mine in a Swedish village. At first, Cronsted thought that the mineral was copper, but the isolated element turned out to be white in color, distinct from copper.

Nickel spheres in which its golden tones shine through. Source: René Rausch

Cronsted named the element nickel and it was later established that the mineral called kupfernickel was nicolite (nickel arsenide).

Nickel is extracted mainly from two deposits: igneous rocks and other segregations of the earth's magma. The minerals are sulfurous in nature, like pentladite. The second source of nickel is laterites, with nickel-rich minerals such as garnierite.

The main application of nickel is in the formation of alloys with many metals; for example, it is involved in the production of stainless steel, an industrial activity that consumes about 70% of the world's nickel production.

In addition, nickel is used in alloys such as alnico, an alloy of magnetic nature destined for the manufacture of electric motors, speakers and microphones.

Nickel began to be used in the making of coins in the middle of the 19th century. However, its use has now been replaced by that of less expensive metals; although it continues to be used in some countries.

Nickel is an essential element for plants, since it activates the enzyme urease that intervenes in the degradation of urea to ammonia, which can be used by plants as a source of nitrogen. Furthermore, urea is a toxic compound that causes serious damage to plants.

Nickel is an element of great toxicity for humans, there is evidence of being a carcinogenic agent. In addition, nickel causes contact dermatitis and the development of allergies.

History

Antiquity

The man knew since ancient times the existence of nickel. For example, a nickel percentage of 2% was found in bronze objects (3500 BC), present in lands currently belonging to Syria.

Likewise, Chinese manuscripts suggest that "white copper", known as baitong, was used between 1700 and 1400 BC. The mineral was exported to Great Britain in the 17th century; but the nickel content of this alloy (Cu-Ni) was not discovered until 1822.

In medieval Germany, a reddish mineral was found, similar to copper, and which had green spots. The miners tried to isolate the copper from the ore, but failed in their attempt. In addition, contact with the mineral produced health problems.

For these reasons, the miners attributed the mineral to a malignant condition and assigned it different names that illustrated this condition; like "Old Nick", also kupfernickel (copper of the devil). Now it is known that the mineral in question was nicolite: nickel arsenide, NiAs.

Discovery and production

In 1751, Axel Fredrik Cronsted tried to isolate copper from kupfernickel, obtained from a cobalt mine located near Los Halsinglandt, a Swedish village. But he only managed to obtain a white metal, which was until then unknown and called it nickel.

Starting in 1824, nickel was obtained as a by-product of the production of cobalt blue. In 1848, a smelter was established in Norway to process the nickel present in the mineral pyrrhotite.

In 1889, nickel was introduced into steel production, and the deposits discovered in New Caledonia provided the nickel for world consumption.

Properties

Appearance

Silvery white, lustrous and with a slight golden tint.

Atomic weight

58.9344 u

Atomic number (Z)

28

Melting point

1,455 ºC

Boiling point

2,730 ºC

Density

-At room temperature: 8.908 g / mL

-At melting point (liquid): 7.81 g / mL

Heat of fusion

17.48 kJ / mol

Heat of vaporization

379 kJ / mol

Molar caloric capacity

26.07 J / mol

Electronegativity

1.91 on the Pauling scale

Ionization energy

First ionization level: 737.1 kJ / mol

Second ionization level: 1,753 kJ / mol

Third level of ionization: 3,395 kJ / mol

Atomic radio

Empirical 124 pm

Covalent radius

124.4 ± 4 pm

Thermal conductivity

90.9 W / (m K)

Electrical resistivity

69.3 nΩ m at 20 ºC

Hardness

4.0 on the Mohs scale.

characteristics

Nickel is a ductile, malleable metal and has a greater hardness than iron, being a good electrical and thermal conductor. It is a ferromagnetic metal at normal temperatures, its Curie temperature being 358ºC. At temperatures higher than this, nickel is no longer ferromagnetic.

Nickel is one of the four ferromagnetic elements, the other three being: iron, cobalt, and gadolinium.

Isotopes

There are 31 isotopes of nickel, limited by ⁴⁸ Ni and ⁷⁸ Ni.

There are five natural isotopes: ⁵⁸ Ni, with an abundance of 68.27%; ⁶⁰ Ni, with an abundance of 26.10%; ⁶¹ Ni, with an abundance of 1.13%; ⁶² Ni, with an abundance of 3.59%; and ⁶⁴ Ni, with an abundance of 0.9%.

The atomic weight of about 59 u for nickel shows that there is not a marked predominance in any of the isotopes (even though ⁵⁸ Ni is the most abundant).

Structure and electronic configuration

Nickel metallic crystallizes into a face centered cubic (fcc) structure. This fcc phase is extremely stable, and remains unchanged up to pressures close to 70 GPa; There is little bibliographic information regarding phases or polymorphs of nickel under high pressure.

The morphology of nickel crystals is variable, since they can be arranged in such a way that they define a nanotube. As a nanoparticle or macroscopic solid, the metallic bond remains the same (in theory); that is, it is the same valence electrons that hold the Ni atoms together.

According to the two possible electronic configurations for nickel:

3d ⁸ 4s ²

3d ⁹ 4s ¹

Ten electrons are involved in the metallic bond; either eight or nine in the 3d orbital, along with two or one in the 4s orbital. Note that the valence band is practically full, close to transporting its electrons to the conduction band; a fact that explains its relatively high electrical conductivity.

Nickel's fcc structure is so stable that it is even adopted by steel when added to it. Thus, stainless iron with a high nickel content is also fcc.

Oxidation numbers

Nickel, although it may not seem like it, also has abundant numbers or oxidation states. The negatives are obvious knowing that it just lacks two electrons to complete the ten of its 3d orbital; thus, it can gain one or two electrons, having oxidation numbers -1 (Ni ^-) or -2 (Ni ^2-), respectively.

The most stable oxidation number for nickel is +2, assuming the existence of the Ni ²⁺ cation, which has lost the electrons of the 4s orbital and has eight electrons in the 3d orbital (3d ⁸).

Also, there are two other positive oxidation numbers: +3 (Ni ³⁺) and +4 (Ni ⁴⁺). At school or high school levels, nickel is only taught to exist as Ni (II) or Ni (III), which is because they are the most common oxidation numbers found in very stable compounds.

And when it is metallic nickel that is part of a compound, that is, with its neutral Ni atom, then it is said to participate or bind with an oxidation number of 0 (Ni ⁰).

Where is nickel found?

Minerals and sea

Nickel constitutes 0.007% of the earth's crust, so its abundance is low. But, it is still the second most abundant metal after iron in the earth's molten core, known as Nife. Seawater has an average nickel concentration of 5.6 · 10 ^-4 mg / L.

It is normally found in igneous rocks, pentlandite, a mineral formed from iron and nickel sulphide, being one of the main sources of nickel:

Rock composed of minerals pentlandite and pyrrhotite. Source: John Sobolewski (JSS)

The mineral pentlandite is present in Sudbury, Ontario, Canada; one of the main deposits of this metal in the world.

Pentlandite has a nickel concentration between 3 and 5%, being associated with pyrrhotite, an iron sulfide rich in nickel. These minerals are found in rocks, products of the segregations of the earth's magma.

Laterites

The other important source of nickel is laterites, made up of arid soils in hot regions. They are poor in silica and possess several minerals, including: garnierite, a magnesium nickel silicate; and limonite, an iron ore

It is used in alloy with iron mainly for the production of stainless steel, since 68% of the nickel production is used for this purpose.

It also forms an alloy with copper, resistant to corrosion. This alloy is made up of 60% nickel, 30% copper and small amounts of other metals, especially iron.

Nickel is used in resistive alloys, magnetic and for other purposes, such as nickel silver; and an alloy consisting of nickel and copper, but does not contain silver. Ni-Cu tubes are used in desalination plants, shielding and in the making of coins.

Nickel provides toughness and tensile strength to alloys that builds resistance to corrosion. In addition to alloys with copper, iron and chromium, it is used in alloys with bronze, aluminum, lead, cobalt, silver and gold.

The Monel alloy is made up of 17% nickel, 30% copper and with traces of iron, manganese and silicon. It is resistant to sea water, which makes it ideal for use on ship propellers.

Protective action

Nickel reacting with fluorine forms a protective layer for the fluorine element, allowing metallic nickel or Monel alloy to be used in the fluorine gas lines.

Nickel is resistant to the action of alkalis. For this reason it is used in containers containing concentrated sodium hydroxide. It is also used in electroplating to create a protective surface for other metals.

Other uses

Nickel is used as a reducing agent for six metals from the platinum group of minerals in which it is combined; mainly platinum and palladium. Nickel foam or mesh is used in the manufacture of electrodes for alkaline fuel batteries.

Nickel is used as a catalyst for the hydrogenation of unsaturated vegetable fatty acids, being used in the process of making margarine. Copper and the Cu-Ni alloy have antibacterial action on E. coli.

Nanoparticles

Nickel nanoparticles (NPs-Ni) find a wide variety of use due to their greater surface area compared to a macroscopic sample. When these NPs-Ni are synthesized from plant extracts, they develop antimicrobial and antibacterial activities.

The reason for the above mentioned is due to its greater tendency to oxidize in contact with water, forming Ni ²⁺ cations and highly reactive oxygen species, which denature microbial cells.

On the other hand, NPs-Ni are used as electrode material in solid fuel cells, fibers, magnets, magnetic fluids, electronic parts, gas sensors, etc. Likewise, they are catalytic supports, adsorbents, bleaching agents and wastewater purifiers.

-Composites

Nickel chloride, nitrate and sulfate are used in nickel baths in electroplating. Furthermore, its sulfate salt is used in the preparation of catalysts and mordants for the dyeing of textiles.

Nickel peroxide is used in storage batteries. Nickel ferrites are used as magnetic cores in antennas in various electrical equipment.

Nickel tertracarbonyl provides carbon monoxide for the synthesis of acrylates, from acetylene and alcohols. The combined oxide of barium and nickel (BaNiO ₃) serves as raw material for the manufacture of cathodes of many rechargeable batteries, such as Ni-Cd, Ni-Fe and Ni-H.

Biological role

Plants require the presence of nickel for their growth. It is known to be used as a cofactor by various plant enzymes, including urease; enzyme that converts urea into ammonia, being able to use this compound in the functioning of plants.

In addition, the accumulation of urea produces an alteration in the leaves of the plants. Nickel acts as a catalyst to promote nitrogen fixation by legumes.

The crops most sensitive to nickel deficiency are legumes (beans and alfalfa), barley, wheat, plums and peaches. Its deficiency is manifested in plants by chlorosis, leaf fall and growth deficiencies.

In some bacteria, the enzyme urease is dependent on nickel, but it is considered that these can have a virulent action on the organisms they inhabit.

Other bacterial enzymes, such as superoxide dismutase, as well as the glyxidase present in bacteria and some parasites, for example in trypanosomes, are dependent on nickel. However, the same enzymes in higher species are not dependent on nickel but on zinc.

Risks

The ingestion of large amounts of nickel is associated with the generation and development of lung, nasal, laryngeal and prostate cancers. In addition, it causes respiratory problems, respiratory failure, asthma, and bronchitis. Nickel fumes can cause lung irritation.

Nickel contact with the skin can cause sensitization, which subsequently produces an allergy, manifested as a skin rash.

Skin exposure to nickel can cause a dermatitis known as “nickel itch” in previously sensitized people. Upon sensitization to nickel, it persists indefinitely.

The International Agency for Research on Cancer (IARC) has placed nickel compounds in Group 1 (there is sufficient evidence of carcinogenicity in humans). However, OSHA does not regulate nickel as a carcinogen.

It is recommended that exposure to metallic nickel and its compounds cannot exceed 1 mg / m ³ for eight hours of work in a forty-hour workweek. Nickel carbonyl and nickel sulfide are highly toxic or carcinogenic compounds.

References

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