Transition metals OCR A Level Chemistry Questions and Answers

Transition metals OCR A Level Chemistry Questions and Answers Which 2 transition metals do not have a fully filled 4s orbital? Chromium and copper What advantage does a fully or half filled shell give a transition metal and why? Makes more stable What is the definition of a transition element? D-block element which form at least one ion with a partially filled d orbital Which 2 elements in the d block do not qualify as transition metals and why? Zinc and scandium. Their ions have full d orbitals and not partially filled d orbitals What are the 3 properties of transition metals? Have variable oxidation states, form coloured compounds and can act as catalysts Give an example of 2 different transition metals with variable oxidation states? Fe 2+ to Fe3+ and Cr2+ to Cr3+ Why do transition metals form coloured compounds? White light is absorbed by some wavelengths in the solution of the metal ion What are the advantages and disadvantages of using transition metals in industry as catalysts? Advantages - reduces energy usage Disadvantages- many TM are toxic Describe an experiment to demonstrate how transition metals act as catalysts? (use equations) Reaction between iodide ions and peroxodisulfide ions catalysed by Fe2+. Normally blue black colour formed when trace of starch added. When Fe3+ is added, black colour forms much more quickly. Overall equation: S2O82- + 2I- - 2SO4 2- + I2 With Fe2+: S2O82- + Fe2+ - 2SO4 2- + Fe3+ Then: Fe3+ + 2I- - I2 + Fe2+ When is a complex ion formed? When one or more molecules bind to central metal atom What is a ligand? A molecule or ion which donates a pair of electrons to a central metal ions to form a coordinate bond What is a dative covalent bond? The bond formed between 2 atoms- one of which provides both electrons for the shared pair What is the coordination number? Number of coordinate bonds Give an example of a monodentate ligand? H2O Give 2 examples of a bidentate ligand? Ethandioate ion or Nh2Ch2Ch2Nh2 (en) Give examples of two complex ions with a tetrahedral shape? CuCl4 and CoCl4 Which elements will form complex ions with a square planar shape? Ag (gold), Pt (platinum) and Pd (palladium) How are cis-trans isomers represented in square planar complexes? Cis- same half, so they are 90 degrees apart (above and below each other on the same side) Trans- 180 degrees away, facing in opposite corners of the square In which kind of molecules does optical isomerism occur in in TM? Octahedral complexes with 2 or more bidentate ligands Draw cisplatin Where does ligand substitution occur in the human body? When carbon monoxide is inhaled it replaces oxygen attached to haemoglobin What colour is the aqueous ion of MnO4 - Purple What colour is the aqueous ion of Cr2O7 2- Orange What colour is the aqueous ion of MnO4 2- Green What colour is the aqueous ion of VO2 + Yellow What colour is the aqueous ion of VO 2+ Blue What colour is the aqueous ion of Ti 3+ Purple What colour is the aqueous ion of V 3+ Green What colour is the aqueous ion of Cr 3+ Green What colour is the aqueous ion of Fe 3+ Yellow What colour is the aqueous ion of Ti 2+ Violet What colour is the aqueous ion of V 2+ Violet What colour is the aqueous ion of Mn 2+ Pale pink What colour is the aqueous ion of Fe 2+ Pale green What colour is the aqueous ion of Co 2+ Pink What colour is the aqueous ion of Ni 2+ Green What colour is the aqueous ion of Cu 2+ Pale blue What colour is the hydroxide and ammonia precipitate with Cu 2+? Blue