Inorganic 2 Section 2 - Unit 23: The Transition Metals Flashcards
State what is meant by the term heterogeneous (1 mark)
- The catalyst is in a different state or phase from the reactants
State three characteristic features of the chemistry of transition metals (3 marks)
- Variable oxidation state
- Act as catalysts
- Form complexes
- Form coloured ions/compounds
Explain what is meant by the term bidentate ligand (1 mark)
- Two atoms that each donate a lone pair (of electrons)
Explain what is meant by the term autocatalysed (1 mark)
A reaction that produces its own catalyst
Describe briefly how colorimetry can be used to determine the concentration of a solution (3 marks)
- Make some known concentrations (of the coloured solution and read the absorbance of each one using a colorimeter)
- Plot a graph of absorbance vs concentration
- Compare unknown concentration from calibration curve
A co-ordinate bond is formed when a transition metal ion reacts with a ligand.
Explain how this co-ordinate bond is formed (2 marks)
- An electron pair on the ligand
- Is donated from the ligand to the central metal ion
Explain, in terms of electrons, why chromium complexes are different colours (6 marks)
- In each of the complexes, the oxidation state of Cr is +3
- And the electron configuration is the same
- But ligands are different
- Different different split of (d) electron energy levels
- Different wavelengths / colours (of light) are absorbed
- Different wavelengths / colours (of light) are
transmitted
State the general property of transition metals that allows the vanadium in vanadium(V) oxide to act as a catalyst in the Contact Process (1 mark)
Variable oxidation states
Write two equations to show how vanadium(V) oxide acts as a catalyst in the Contact Process (2 marks)
- V₂O₅ + SO₂ → V₂O₄ + SO3
- V₂O₄ + ½O₂ → V₂O₅
Give one reason why impurities in the reactants can cause problems in processes that use heterogeneous catalysts (1 mark)
Impurities poison / deactivate the catalyst / block the active sites
Explain the meaning of the terms ligand and bidentate as applied to transition metal complexes (2 marks)
- A ligand is an electron pair / lone pair donor
- A bidentate ligand donates two electron pairs (to a transition metal ion) from different atoms / two atoms (on the same molecule / ion)
Other than octahedral, there are several different shapes shown by transition metal complexes. Name three of these shapes and for each one give the formula of a complex with that shape (6 marks)
- Tetrahedral
- [CuCl4]2– / [CoCl4]2–
- Square planar
- (NH3)2PtCl2
- Linear
- [Ag(NH3)2]+
Explain why the Zn2+ ion is not classified as a transition metal ion (1 mark)
- d sub-shell full
In terms of bonding, explain the meaning of the term complex (2 marks)
- Atom or ion bonded to one or more ligands
- By co–ordinate / dative (covalent) bonds
By reference to aqueous copper(II) ions, state the meaning of each of the three terms in the equation ΔE = hv (3 marks)
- ΔE is the energy gained by the (excited) electrons (of Cu2+
- h (Planck’s) constant
- v frequency of light (absorbed by Cu2+(aq))
Give the meaning of the term multidentate (1 mark)
Forms two or more co-ordinate bonds