NICKEL A close-up view of nickel shot. Nickel metal is hard, white, and lustrous, and is similar in apperance to cobalt.

Physical Properties

Atomic Number: 28
Mass Number: 58.69
Electron Configuration: 1s²2s²2p⁶3s²3p⁶4s²3d⁸
Crystal Structure: Face-Centered Cubic
Atomic Radius: 115 pm
Density: 8.90 g/cm³
Melting Point: 1453 ^oC
Important Oxidation States: +2

The Colors of Nickel(II). In aqueous solution, the nickel(II) is always green due to the formation of [Ni(H2O)6]2+. In a solution with a high ammonia solution, the color changes to violet due to the formation of [Ni(NH3)6]2+as the coordinated water molecules are replaced with ammonia molecules.

A chemical test for Ni(II). When dimethylgloxime (DMG) is added to a solution containing the Ni(II) ion, a characteristic red complex is formed.