Study guide

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In this section, a rather large amount of information in a somewhat traditional and descriptive fashion, namely, a steady "march" through the metals of the first transition series and their compounds, is presented. For each element the important or interesting properties of the element and its inorganic compounds are presented. You should find it satisfying that the descriptions of the compounds and their reactivities are readily set down in the same "language" and using the same theories as those developed during the first module.

After completion of this module you should be able to:

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4.3.1 General coordination properties:

P explain what process will readily take place with L.O.S. metals if B-acceptor ligands are not available for bonding;

P rationalize the type of coordination compounds normally found for L.O.S. metals;

P explain why the bonding in M.O.S. metals can either be highly ionic or highly covalent;

P explain why the early 3d transition metals dissolve in HF whereas the later 3d's dissolve in HCN;

P discuss the occurrence of six and four coordinated complexes of M.O.S. 3d transition metals;

P explain how L.O.S. 3d transition elements may be stabilized;

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4.3.2 Titanium:

P write down the electronic configuration of Ti in all of its common oxidation states;

P predict the most important stereochemistries of Ti in all its common oxidation states;

P write down the balanced reaction when TiCl₄ is dissolved in H₂O and the mixture left to stand and fully explain the chemistry involved in this reaction;

P write down a balanced reaction to show how alkyltitanates can be formed;

P explain the hydrolysis of alkyltitanates;

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4.3.3 Vanadium:

P write down the electronic configuration of V in all of its common oxidation states;

P predict the most important stereochemistries of V in all of its common oxidation states;

P explain what happens when a solution of ammonium metavanadate in sulfuric acid is shaken with zinc amalgam;

P explain why, in the O = V = O unit, the two oxygen atoms are in cis-position compared to the transition metal dioxide units where the oxygen atoms are in trans positions, as for example in RuO₂²⁺, ReO₂²⁺, etc.;

P explain why when V^III solutions are reduced by Zn in acid, violet air-sensitive solutions of V(H₂O)₆²⁺ are obtained which are oxidized by H₂O with the evolution of H₂ despite the fact that the V^III / V^II potential suggests otherwise;

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4.3.4 Chromium:

P describe the extraction of pure chromium from the ore, chromite, giving balanced reactions for all the reactions taking place;

P write down the electronic configuration of Cr in all of its common oxidation states;

P predict the most important stereochemistries of Cr in all of its common oxidation states;

P explain what factors contribute to the stability of chromium(II) acetate despite the fact that Cr^II compounds are highly reducing;

P explain why the enormous number of Cr^III compounds known is largely due to kinetic considerations;

P explain why CrCl₃ is only soluble in the presence of small quantities of CrCl₂;

P explain why acid solutions of dichromate are strong oxidants;

P explain why dichromate is much less oxidizing in alkaline solution;

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4.3.5 Manganese:

P write down the electronic configuration of Mn in all of its common oxidation states;

P predict the most important stereochemistries of Mn in all of its common oxidation states;

P describe the uses of MnO₂;

P explain why Mn can exist in oxidation states up to a maximum of +VII;

P explain why most manganese(II) complexes are octahedral and high-spin;

P explain why Cr(II) is a better reducing agent than Mn(II);

P explain the chemistry involved for the reactions that occur when NaOH is added to a Mn²⁺ solution and the mixture is exposed to the atmosphere;

P explain why [Mn(H₂O)]²⁺ is stable whereas [Mn(CN)₆]^4- can be easily oxidised or reduced in aqueous solution;

P explain why [Mn(H₂O)₆]²⁺ is pale pink, MnO₂ is black and MnO₄^- is intensely purple-coloured;

P explain the disproportionation of Mn³⁺ in weakly acidic solutions;

P explain why KMnO₄ is stable in very basic solutions but decomposes in neutral, acidic or slightly basic solutions.

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P write down the electronic configuration of Fe in all of its commonly occurring oxidation states;

P predict the most important stereochemistries of Fe in all of its commonly occurring oxidation states;

P discuss, with the aid of balanced equations, the preparation of Fe in a blast furnace;

P discuss the rusting of iron and steel and methods used to prevent it;

P explain what happens when OH⁾ is added to a solution of FeCl₂ and the mixture left to stand;

P explain the variation in the redox potentials of the Fe²⁺ / Fe³⁺ couple in the presence of the ligands CN⁾, H₂O and phenanthroline;

P explain what happens when a solution of KI is added to an Fe³⁺ solution;

P explain what happens when a solution of NaF is added to an Fe(SCN)₃ solution;

P explain why Fe(CN)₆^3- is poisonous, whereas Fe(CN)₆^4- is far less poisonous;

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4.3.7 Cobalt:

P write down the electronic configuration of Co in all of its common oxidation states;

P predict the most important stereochemistries of Co in all of its common oxidation states;

P explain why freshly precipitated Co(II) hydroxide is blue but turns pink on warming;

P explain why Co(II) is the only d⁷ ion of common occurrence;

P explain why Co(H₂O)₆²⁺ is perfectly stable but Co(CN)₆^4- is readily oxidized to Co(CN)₆^3-;

P explain why all known complexes of Co(III) are octahedral;

P discuss and explain the disproportionation of Co(II);

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P write down the electronic configuration of Ni in its common oxidation state;

P predict the most important stereochemistries of Ni in its common oxidation state;

P describe the preparation of 99.9% pure Ni from NiO;

P briefly rationalize the fact that Ni(II) can form octahedral, tetrahedral, square-planar and five-coordinated compounds;

P explain why most four-coordinated Ni(II) compounds are square-planar;

P discuss the bonding in the nickel(II) dimethylglyoxime complex in the solid state.

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4.3.9 Copper:

P write down the electronic configuration of Cu in its common oxidation states;

P predict the most important stereochemistries of Cu in its common oxidation states;

P describe the extraction of copper from the ore CuFeS₂;

P briefly explain why Cu⁺ compounds are essentially covalent whereas the alkali metals, which have a similar electronic configuration, form essentially ionic compounds;

P briefly explain why Cu(I) can act as a reducing agent in aqueous solutions while in CH₃CN solutions, Cu(II) may act as an oxidizing agent;

P explain what happens when iodide is added to a Cu²⁺ solution.

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The project will take the form of a poster plus an oral presentation of the poster. You  will be assigned one of the eight transition elements studied in this module. You will make an interesting, concise and colourful poster and you will orally present  the poster. You could be asked to cover the following headings/subject matter in your oral and poster presentation: (these details may differ from year to year)

Evaluation:

You will be evaluated on your oral presentation as well as on the content and quality of your poster. There will be small prizes for the best posters.

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