Question

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6. Consider iron (II) chloride, FeCl2. (a) What is the ratio of the cationic to the anionic radius? (b) Based on this ratio, what type of coordination geometry does it form? (c) What is the coordination number? (d) Is FeCl isomorphous with SiO2, which has a tetrahedral coordination geometry? Why or why not? (4 marks) 7. Based on their chemical formulas, what is the structure (e.g. sheet silicate) for the following minerals? a) liberite, LizBeSiO4; (b) jadeite, NaAlSi206? (2 marks)

Answer 1

The radius ratio gives relationship between the radius coordination number the structural arrangement of molecules in an atom. It is defines as the ratio of radius of cation to radius of anion therefore In Fecl_2 radius ratio < 0.155 (because coordinate of Fe is Fe^+ 2) Coordination Geometry - linear Coordination number = 2