Nickel(II) nitrate

Nickel nitrate is the chemical compound Ni(NO3)2 or any hydrate thereof. The anhydrous form is not commonly encountered, thus "nickel nitrate" usually refers to nickel(II) nitrate hexahydrate. The formula for this species is written in two ways. Ni(NO3)2.6H2O and, more descriptively [Ni(H2O)6](NO3)2. The latter formula indicates that the nickel(II) center is surrounded by six water molecules in this hydrated salt. The nitrate anions are not bonded to nickel.

[Ni(H2O)6](NO3)2 is highly soluble in water, giving emerald green solutions. It is a useful precursor to other nickel(II) derivatives where the water ligands would be replaced.

When ions form, the outermost electrons (highest n value) are lost first, which results in the electron configuration of 1s2 2s2 2p6 3s2 3p6 3d8, instead of ...4s2 3d6.

Safety
Like other nitrates, nickel nitrate is oxidizing, so that caution should be exercised when it contacts with reducing materials such as organic substances. It is also irritating to the eyes, skin and, upon inhalation of the dust, respiratory tract. It may cause skin allergy. Nickel nitrate is a suspected carcinogen, along with most other nickel compounds. The nickel ion is also toxic to aquatic organisms.