Chemical characteristics of Nickel

Chemical characteristics of Nickel

Peripheral electronic arrangement 3d4s, located in the fourth cycle of Group VIII. Chemical properties more lively, but more stable than iron. Room temperature in the air difficult to oxidation, not easy to react with concentrated nitric acid. Fine nickel wire flammable, heated with halogen reaction, dissolved slowly in dilute acid. Can absorb a considerable amount of hydrogen.

Nickel is insoluble in water, forming a dense oxide film on the surface of humid air at room temperature, which can prevent the body metal from continuing to oxidize. In dilute acid can be slowly dissolved, the release of hydrogen to produce green positive divalent nickel ion Ni; resistant to alkali. Nickel can be burned in pure oxygen, emitting brilliant white light. Similarly, nickel can also be burned in chlorine and fluorine. No reaction to the oxidizer solution, including nitric acid. Nickel is a medium strength reductant. Nickel hydrochloric acid, sulfuric acid, organic acids and alkaline solution of nickel etching very slow. Nickel slowly dissolves in dilute nitric acid. Fuming nitric acid can passivate the nickel surface with corrosion resistance. Nickel, like platinum and palladium, can absorb a large amount of hydrogen during passivation. The smaller the particle size, the larger the absorption. Important nickel salts are nickel sulfate and nickel chloride. Nickel nitrate is also commonly used in laboratories, with crystal water, Ni (NO3) 2 • 6H2O chemical formula, green and transparent particles, easy to absorb water vapor in the air. Similar to iron and cobalt, it is stable to water and air at room temperature and is resistant to alkaline corrosion. Therefore, a nickel crucible can be used in laboratories to melt alkali. Nickel sulfate (NiSO4) can form alum Ni (SO4) 2o6H2O with alkali metal sulfate (MI is an alkali metal ion). +2 nickel ions can form coordination compounds. Under normal pressure, nickel reacts with carbon monoxide to form highly toxic nickel (Ni (CO) 4), which decomposes to metallic nickel and carbon monoxide upon heating.

Atomic number 28

Atomic weight 58.71

Metal radius 124.6 picometer

The first ionization energy 741.1kJ / mol

Electronegativity 1.8

The main oxidation number +2, +3, +4

Nickel (II) compounds

1. Nickel oxide: NiC2O4 = NiO + CO + CO2

2. Nickel hydroxide: Ni + 2OH = Ni (OH) 2

3. Nickel sulfate 2Ni + 2H2SO4 + 2HNO3 = 2NiSO4 + NO2 + NO + 3H2O

NiO + H2SO4 = NiSO4 + H2O

NiCO3 + H2SO4 = NiSO4 + CO2 + H2O

4. Halide of nickel: NiF2, NiCl2, NiBr2, NiI2

Nickel (III) compounds

High-nickel oxide

4NiO + O2 == 2Ni2O3

2Ni (OH) 2 + Br2 + 2OH == Ni2O3 + 2Br + 3H2O

2Ni2O3 + 4H2SO4 == 4NiSO4 + O2 + 4H2O

Ni2O3 + 6HCl == 2NiCl2 + Cl2 + 3H2O

2. High-nickel hydroxide

4NiCO3 + O2 == 2Ni2O3 + 4CO2

2Ni (OH) 2 + NaClO + H2O == 2Ni (OH) 3 + NaCl

2Ni (OH) 3 + 6HCl == 2NiCl2 + Cl2 + 6H2O

Collapse complex

1. Ammonia Coordination Compounds: [Ni (NH3) 6]

2. Cyano complex compounds: [Ni (CN) 4]

3. Chelate: [Ni (en) 3]

4 carbonyl coordination compounds

(a) Ni (CO) 4

(b) (C2H5) 2Ni