Nikl / Nickel (Ni)

Nikl je hemijski element sa simbolom Ni i atomskim brojem 28. Otporan je na koroziju u različitim sredinama, te na djelovanje atmosferskih plinova (na zraku sporo oksidira), vode, halogenih elemenata i sumpora na sobnoj temperaturi, a zagrijavanjem mu se reaktivnost povećava. Otporan je prema lužinama sve do 500 °C, u neoksidativnim kiselinama otapa se vrlo sporo, a u razrijeđenim oksidirajućim kiselinama brzo. Tali se na temperaturi od 1450 °C.
On je srebrenasto-svijetli sjajni metal sa blagim zlatnim nijansama. Nikl pripada prelaznim metalima, veoma je tvrd i duktilan.   Čak i u tom slučaju, nikl je dovoljno reaktivan sa kisikom pa se nikl vrlo rijetko može naći na površini Zemlje.
Hemijski element nikl je prvi put izolirao i klasificirao Axel Fredrik Cronstedt 1751. godine, koji je prvobitno pogrešno identificirao njegovu rudu kao mineral bakra.
Kako je izrazito otporan na koroziju, koristi se za galvansko prevlačenje drugih metala radi zaštite. Slitine nikla i bakra se koriste za izradu kovanog novca, pribora za jelo, itd.

Nickel is a chemical element of atomic (ordinal) number 28. In the periodic table of elements it is represented by the symbol Ni.
It is resistant to corrosion in various environments, and to the action of atmospheric gases (slowly oxidizes in air), water, halogen elements and sulfur at room temperature, and its reactivity increases when heated. It is resistant to alkalis up to 500 ° C, dissolves very slowly in non-oxidizing acids and quickly in dilute oxidizing acids. It melts at a temperature of 1450 ° C.
It is a silvery-bright shiny metal with slight golden hues. Nickel belongs to transition metals, it is very hard and ductile. Even in this case, nickel is sufficiently reactive with oxygen so nickel can very rarely be found on the Earth's surface.
The chemical element nickel was first isolated and classified by Axel Fredrik Cronstedt in 1751, who originally misidentified its ore as a copper mineral.
As it is extremely resistant to corrosion, it is used for galvanic coating of other metals for protection. Nickel and copper alloys are used to make coins, cutlery, etc.