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INORGANIC
Part 10 3d block TRANSITION METALS sub-index: 10.1-10.2
Introduction 3d-block Transition Metals * 10.3
Scandium
* 10.4 Titanium * 10.5
Vanadium * 10.6 Chromium
* 10.7 Manganese * 10.8
Iron * 10.9 Cobalt
* 10.10 Nickel
* 10.11 Copper * 10.12
Zinc
* 10.13 Other Transition Metals e.g. Ag and Pt * Appendix 1.
Hydrated salts, acidity of
hexa-aqua ions * Appendix 2. Complexes
& ligands * Appendix 3. Complexes and isomerism * Appendix 4.
Electron configuration & colour theory *
Appendix 5. Redox
equations, feasibility, Eø * Appendix 6.
Catalysis * Appendix 7.
Redox
equations
* Appendix 8. Stability Constants and entropy
changes *
Appendix 9. Colorimetric analysis
and complex ion formula * Appendix 10 3d block - extended data
* Appendix 11 Some 3d-block compounds, complexes, oxidation states
& electrode potentials * Appendix 12
Hydroxide complex precipitate 'pictures',
formulae and equations
Advanced
Level Inorganic Chemistry Periodic Table Index *
Part 1
Periodic Table history
* Part 2
Electron configurations, spectroscopy,
hydrogen spectrum,
ionisation energies *
Part 3
Period 1 survey H to He *
Part 4
Period 2 survey Li to Ne * Part
5 Period 3 survey Na to Ar *
Part 6
Period 4 survey K to Kr and important trends down a
group *
Part 7
s-block Groups 1/2 Alkali Metals/Alkaline Earth Metals *
Part 8
p-block Groups 3/13 to 0/18 *
Part 9
Group 7/17 The Halogens *
Part 10
3d block elements & Transition Metal Series
*
Part 11
Group & Series data & periodicity plots * All
11 Parts have
their own sub-indexes near the top of the pages
10.10. Chemistry
of Nickel
Ni, Z=28, 1s22s22p63s23p63d84s2
-
Ni
data table 1 summary
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extended nickel data table 2
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Nickel & electrode potential chart
of 3d-block
-
Summary of some
complexes-compounds & oxidation states of nickel compared to other
3d-block elements
-
Nickel has
many uses from 'silver' coinage metals and monel used for chemical
reactors - both are alloys with copper to give a chemically inert
metal.
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Nickel is an important
hydrogenation catalyst in converting unsaturated vegetable oils to
saturated fats like margarine.
-
unsaturated oil +
hydrogen ==> low melting solid more saturated fat
-
Along the carbon
chain of the oil you get: -CH=CH- + H2 ==> -CH2-CH2-
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NICKEL(II) CHEMISTRY
-
In aqueous solution
nickel forms the green stable hexaaqua nickel(II) ion, [Ni(H2O)6]2+
(aq)
-
The alkalis sodium
hydroxide or ammonia, produce the hydrated
nickel(II) hydroxide
green?
precipitate. There is no further reaction with excess
of NaOH, but see further down for excess NH3.
-
Alkaline aqueous
sodium carbonate solutions produces a precipitate of green ppt. of nickel(II) carbonate.
-
With excess aqueous
ammonia the blue hexa-ammine complex ion is formed:
-
[Ni(H2O)6]2+(aq)
+ 6NH3(aq)
[Ni(NH3)6]2+(aq)
+ 6H2O(l)
-
[Ni(H2O)6]2+(aq) + 6NH3(aq)
==> [Ni(NH3)6]2+(aq) + 6H2O(l)
-
You can write
equation of the ammine complex from the dissolving of nickel(II) hydroxide
precipitate.
-
With lower
concentrations of ammonia the pale blue complex can also have the structure
[Ni(H2O)2(NH3)4]2+
-
The hexa-aquanickel(II)
ion also forms complexes with other amine ligands
-
e.g. the bidentate
ligand 1,2-diaminoethane (H2N-CH2-CH2-NH2,
often abbreviated to en)
-
[Ni(H2O)6]2+(aq)
+ 3en(aq) ===> [Ni(en)3]2+(aq)
+ 6H2O(l)
-
The complex with EDTA is
also readily formed.
-
[Ni(H2O)6]2+(aq)
+ EDTA4-(aq) ===> [Ni(EDTA)]2-(aq)
+ 6H2O(l)
-
Note that Kstab
for the same ion tend to increase the greater the chelating power of
an individual ligand in terms of the ligand bond formed - mainly due
to the increase in entropy as more particles are formed by the
polydentate ligands
-
e.g. for the same
nicke(II) ion Kstab(EDTA) > Kstab(en)
> Kstab(NH3)
-
VIEW ppts. with OH-, NH3
and CO32-, & complexes,
if any, with
excess reagent.
-
Other complexes of nickel
-
Nickel carbonyl,
Ni(CO)4, is a neutral complex tetrahedrally shaped covalent
molecule. Note (i) nickel is in a zero oxidation state and (ii) the ligand CO also acts as ligand with haemoglobin
(hemoglobin) in carbon monoxide poisoning.
-
Ni2+ forms
the tetrachloronickelate(II) ion, [NiCl4]2-, a
tetrahedral anionic complex
with the chloride ion (Cl-).
-
[Ni(H2O)6]2+(aq) +
4Cl-(aq)
==> [NiCl4]2-(aq) + 6H2O(l)
-
Kstab
= {[NiCl4]2-(aq)}
/ {[Ni(H2O)6]2+(aq)}
[Cl-(aq)]4
-
Kstab
= ? mol4 dm-12 [lg(Kstab)
= ?]
-
Ni2+ forms
the tetracyanonickelate(II) ion, [Ni(CN)4]2-, a
square planar anionic complex
with the cyanide ion (CN-).
-
[Ni(H2O)6]2+(aq) +
4CN-(aq)
==> [NiCN4]2-(aq) + 6H2O(l)
-
Kstab
= {[NiCN4]2-(aq)}
/ {[Ni(H2O)6]2+(aq)}
[CN-(aq)]4
-
Kstab
= 2 x 1031 mol4 dm-12
[lg(Kstab) = 31.3]
-
Its likely that the more
bulky chloride ion (radius Cl > C) 'forces' the formation of the
tetrahedral shape rather than a square planar shaped complex.
Scandium
* Titanium * Vanadium
* Chromium
* Manganese * Iron * Cobalt
* Nickel
* Copper *
Zinc
* Silver & Platinum
Copyright
© Dr W P Brown 2000-2010
All rights reserved on the revision notes pages, quizzes, worksheets, x-words
etc.
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