CIE Nov 2014 v2 Paper 4 Q2

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(a) Complete the electron con gurations for Ni and Ni2+. Ni [Ar] Ni2+ [Ar] 3d 4s PMT [2] (b) The presence of electrons in d orbitals is responsible for the colours of transition element compounds. (i) The d orbitals in an isolated transition metal atom or ion are all at the same energy level. What term is used to describe orbitals that are at the same energy level?(ii) Complete the diagram to show the splitting of the d orbital energy levels in an octahedral complex ion. energy (iii) On the axes below, sketch the shapes of one d orbital from the lower energy level and one d orbital from the higher energy level. lower energy level higher energy level [4]UCLES 2014 9701/42/O/N/14<br />
 PMT (c) The octahedral complex [Ni(H2O)6]2+ is green. Explain the origin of the colour of this complex.[3] (d) When NH3(aq) is added to the green solution containing [Ni(H2O)6]2+, a grey-green precipitate, A, is formed. This precipitate dissolves in an excess of NH3(aq) to give a blue-violet solution, B. Suggest formulae for A and B and write equations for the two reactions producing A and B.[4] [Total: 13]UCLES 2014 9701/42/O/N/14 [Turn over<br />

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