We explain what nickel is, how it was discovered, how it is obtained, used and other properties. In addition, allergy to nickel.
What is nickel?
Nickel is a chemical chemical element, located in group 10 of the Periodic Table of the Elements, and represented by the symbol Ni . Its atomic number is 28 and is part of the so-called transition metals, such as zinc, cadmium or mercury.
Together with copper, it is one of the most known and used metals by mankind throughout its history. Nickel has five isotopes in nature, being the lightest also the most abundant (68%), and eighteen radioactive isotopes, whose longest half-life is 76, 000 years.
Its name goes back to the German word Kupfernickel, whose origins are debated, but it would mean "false copper." Some explanations attribute it to the nickname that the miners gave to the devil ("the old Nick" or Nikolaus ), since they assumed that nickel, similar in appearance to copper, was a form of deception to the greedy.
See also: Metallic bond
Nickel was known to mankind since the fourth century BC. C. It is known that its discovery was simultaneous to that of copper, since it is common to find it in the minerals in which the latter metal abounds.
For example, it was used in ancient Mesopotamia (Syria) where bronzes were found that have levels higher than 2% nickel content. Many ancient Chinese manuscripts suggest that the "white copper" used in the East between 1700 and 1400 a. C. It was not really but nickel.
Importance of Nickel
Nickel was neglected for a long time, nicknamed "false copper" and had a useless or less valuable metal. Today that has changed. Although it is certainly not a precious metal, it is one of the most demanded in the industry for the manufacture of coins and as a material for alloys with iron, silver and other metals.
In addition, it is essential for microbial metabolism, since 87% of hydrogenases, enzymes dedicated to the oxidation of hydrogen in microbes, contain high percentages of nickel as an active component.
Nickel is the second most abundant metal on Earth (iron being the first). In fact, the core of our planet has very pure levels of both metals.
It is common to find it inside certain meteorites, alloyed with iron and forming the minerals kamacita and taenite. In addition, in combination with other metals can be found in the minerals Garnierite, Millerite, Pentlandite, Nickelin and Pyrrotite.
The main nickel mines in the world are in Canada, Cuba and Russia, countries that meet 70% of the global demand for this metal. Other important producers are Bolivia, Colombia, New Caledonia and the Dominican Republic.
Nickel has a typical yellowish white color, capable of being confused with copper (as in fact happened in the past). Many of its properties are similar to those of iron, a metal with which it shares an enormous density, as well as with osmium and iridium.
It is a good conductor of electricity and heat, ferromagnetic at room temperature. Since it is extremely flexible and malleable, it is laminated, polished and forged very easily.
Its usual oxidation state is +2, although it has also been seen in other states (0, +1 and +3), and is generally resistant to corrosion, without suffering the so-called Galleo effect. At the same time, it is carcinogenic and highly toxic.
Uses of nickel
Nickel is widely used in metallurgy, in alloys of iron, silver and other metals, which it protects against corrosion. Thus, stainless steel is obtained, among other superalloys, such as copper-nickel ( monel ), nickel-titanium ( nithinol-55 ), n quel-iron ( mu-metal ) and the alnico (aluminum-nickel-cobalt alloy) from which the magnets are manufactured.
It is also widely used in the manufacture of coins, being so common that in the United States the term nickel is used to refer to the smallest and least valuable currency.
It is also used in watchmaking and, in jewelry, is a component of the so-called "white gold". However, the use of nickel plating is inadvisable given the high level of toxicity of the metal. It is part of the manufacture of rechargeable batteries . In addition, it is a common catalyst element in different chemical reactions.
Nickel is a toxic and carcinogenic metal, especially its vapors and nickel sulfate, as well as nickel carbonyl (Ni [CO] 4 ), a common but extremely toxic gas. Likewise, there are many people sensitive to nickel in a state of purity, capable of manifesting allergies to contact.
Therefore, the levels of this metal present in objects intended to come into contact with human skin are usually regulated nationally and internationally. It is considered 0.05 mg / cm 3 as the maximum nickel to which a person can be exposed for eight hours a day and forty weeks without suffering serious health risks.