Nickel is a chemical element with the symbol Ni and atomic number 28, It is a ferromagnetic metal of Group 10 (VIIIb) of the periodic table, It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile. Pure nickel, powdered to maximize the reactive surface area, shows a significant chemical activity, but larger pieces are slow to react with air under standard conditions because an oxide layer forms on the surface and prevents further corrosion (passivation). Even so, pure native nickel is found in Earth’s crust only in tiny amounts, usually in ultramafic rocks and in the interiors of larger nickel–iron meteorites that were not exposed to oxygen when outside Earth’s atmosphere. Meteoric nickel is found in combination with iron, a reflection of the origin of those elements as major end products of supernova nucleosynthesis. An iron–nickel mixture is thought to compose Earth’s outer and inner cores.
Physical properties of Nickel
- It is a silvery-white metal with a slight golden tinge that takes a high polish. It is one of only four elements that are magnetic at or near room temperature, the others being iron, cobalt and gadolinium.
- Its Curie temperature is 355 °C (671 °F), meaning that bulk nickel is non-magnetic above this temperature. The unit cell of nickel is a face-centered cube with the lattice parameter of 0.352 nm, giving an atomic radius of 0.124 nm. This crystal structure is stable to pressures of at least 70 GPa. Nickel belongs to the transition metals.
- It is hard, malleable and ductile, and has a relatively high for transition metals electrical and thermal conductivity. The high compressive strength of 34 GPa, predicted for ideal crystals, is never obtained in the real bulk material due to the formation and movement of dislocations; however, it has been reached in Ni nanoparticles.