5.3.1 0.0 / 5 ? ChemistryTransition ElementsA2/A-levelOCR Created by: Lara_BryceCreated on: 31-05-18 21:51 What are transition elements? A d-block element which forms an ion with an incomplete d sub-shell. 1 of 18 How are coloured compounds formed? The solid compounds are dissolved in water to produce coloured solutions. 2 of 18 How can transition elements be used as catalysts? Fe in the Haber process; Vanadium (V) oxide, V2O5, to produce SO3 from SO2; Ni in manufacture of margarine. 3 of 18 What is a complex ion? A transition metal ion bonded to ligands by coordinate (dative covalent) bonds. 4 of 18 What is a ligand? A molecule or ion that can donate a pair of electrons to the transition metal ion. 5 of 18 Give some examples of monodentate and bidentate ligands. Mono - H2O, NH3, Cl-, CN-; Bi - NH2 CH2CH2 NH2. 6 of 18 What shape do complex ions with a coordination number of 6 have? Octahedral shape, and angle of 90. 7 of 18 What shape do complex ions with a coordination number of 4 have? Tetrahedral, bond angle 109.5; square planar, bond angle 90. 8 of 18 When do complex ions have a square planar shape? This shape occurs in complex ions of transition metals with 8 d-electrons in the highest energy d sub-shell; complexes of Pt. 9 of 18 Draw the cis and trans isomers of Pt (NH3)2 Cl2. See green 5.3.1 flashcard 1. 10 of 18 When does optical isomerism occur? In octahedral complexes containing two or more bidentate ligands; it must also be a cis isomer. 11 of 18 How s cis-platin used in cancer treatment? Cis-platin forms a platinum complex inside a cell which binds to DNA and stops the DNA from replicating.; unpleasant side effects, kidney damage 12 of 18 Do you know the ligand substitution or precipitation reactions for Cu 2+, Fe 2+, Fe 3+, Mn 2+ and Cr 3+? See 3 printed sheets from Mr Horner. 13 of 18 How does haemoglobin use ligand substitution? O2 binds to Fe 2+ in the haemoglobin; CO can also bind to Fe 2+ and will replace O2 as the CO binds more strongly. 14 of 18 Explain the reduction of Fe 3+ to Fe 2+. Fe 3+ is reduced to Fe 2+; I - is oxidised to I2; orange-brown to pale-green and brown. 15 of 18 Explain the oxidation of Fe 2+ to Fe 3+. Fe 2+ is oxidised to Fe 3+; MnO4 - is reduced to Mn 2+; purple to colourless. 16 of 18 Explain the reduction of Cr2O7 2- to Cr 3+. Orange to green; with excess zinc, green to pale blue. 17 of 18 Explain the reduction of Cu 2+ to Cu +. Cu 2+ is reduced to Cu +; I - is oxidised to I2; pale blue to brown with a white precipitate. 18 of 18
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