Indicate exactly (% and T) where the eutectic point is located Temperature (°C) 2200 2000 Liquid 1800 1600 Cristobalite + Liquid 40 60 80 18 4000 3800 Liquid 3600 + Alumina 3400 1890 ± 10°C Mullite (ss) Mullite (ss) + Liquid Alumina Mullite (ss) 1587 ± 10°C Mullite (ss) + Cristobalite 1400 0 20 40 (SiO2) L 3200 3000 2800 2600 60 80 100 (Al2O3) Composition (wt% Al2O3) Temperature (°F)

18. Explain with the help of partial molecular orbitals the difference between an acceptor and a donor ligand. 19. Construct molecular orbital diagram consistent with [Ni(NH))6]² 20. Draw the molecular orbital diagrams of (a) (b) [FeCle] [Fe(CN)6]³ Determine whether the complexes are high spin or low spin What is the total number of molecular orbitals of each complex ion Calculate the ligand field stabilization energy and the spin only magnetic moment of each complex ion.

Calculate the value of the ionic packing factor of CsI, which has a CsCl structure, knowing that the radius of Cs+ is 0.165 nm and that of I– is 0.220 nm.

Calculate the atomic packing factor of quartz, knowing that the number of Si atoms per cm3 is 2.66x1022 and that the atomic radii of Si and O are 0.038 and 0.117 nm.

Choose one or more: Draw the Lewis structure. Consider and draw alternate resonance structures. Calculate the molar mass of the compound. Leave out the lone pairs of electrons. Complete the octets of each atom (dublet for H). Determine the central atom, if possible. Determine the number of covalent bonds in the structure. Check the structure with electron bookkeeping   Question: Determine which of the following procedures are steps in drawing the resonance structures of pyridine and pyrazine. Check all that apply.

1. Draw the shapes of the various d orbitals and explain why they are split into two groups; 12g and eg in an octahedral field Draw a diagram to show how the d orbitals are split into groups with different energy in an octahedral field. Some electronic configurations may exist in both high spin and low spin arrangements in an octahedral field. Draw all of these cases, and suggest which metal ions and which ligands might give rise to each. Draw an energy level diagram to show the lifting of degeneracy of the 3d orbitals in a tetrahedral ligand field . Give the number of unpaired electrons in a strong and weak octahedral field for (a) Cr² (b) Co and (c) Fe. Calculate the CFSE and magnetic moment in each case

9. Describe and explain the Jahn teller effect in octahedral complexes of Cu² and Cr Define paramagnetism and diamagnetism. What is the difference between an inner orbital complex and an outer orbital complex? The complex [NiCN)4] is diamagnetic, but [NiCla] is paramagnetic and has two unpaired electrons, explain these observations and deduce the structures of the two complexes The complex ion [Co (NH3)6] is octahedral and diamagnetic, the complexion [CoF6] is also octahedral but paramagnetic. How does valence bond theory account for this observation? How does crystal field explain color of complexes?

5. Show how the d orbital splitting changes as an octahedral complex undergoes tetragonal distortion and eventually becomes a square planar complex. What is the spectrochemical series and what is its importance Using crystal field theory, (a) Draw the d-orbital electronic configuration of [Cr(CN)6]³ (b) How many unpaired electrons are present? (c) Calculate the CFSE and magnetic moment of the complex ion (c) If six Br groups were substituted for the six CN groups to give [CrBr.]³ would you expect Ao to increase or decrease? Why? Describe how Ao changes as the charge on the metal changes from M² to M and how it changes between a first row, second row or third row transition element.

15. Describe clearly how crystal field theory explains satisfactorily the magnetic moment of transition metal complexes. Which complex has the larger crystal field splitting? Give reasons for your answer. (i) [Co(CN)6] or (ii) [Co(H2O)²+ or (iii) [Co(NH)6] or [Co(NH3)6] [Co(H_O)] [Rh(NH3)]* What relationship exist between A (the crystal field splitting) and the pairing energy (P) in determining whether a given complex will be high spin or low spin.