Nickel is a chemical element of symbol Ni of atomic number 28 (28 protons and 28 electrons) and of atomic mass 58,7 uma. At room temperature, it is in the solid state. It is a transition element situated in group 10 (8 B) of the Periodic Classification of Elements.

It is a transition metal of white-silver coloration, conductor of electricity and heat, ductile and malleable but cannot be laminated, polished or forged easily, presenting a certain ferromagnetic character. It is found in various minerals, in meteorites (forming a metal alloy with iron) and, in principle, there is nickel in the Earth’s core.