CAIE A-Level Chemistry 28.2.6 Coordination Number and Complex Formula

Practise finding coordination numbers and constructing complex-ion formulae from metal charge, ligand charge and denticity.

Exam points

define coordination number as the number of coordinate bonds formed to the central metal atom or ion
count both donor atoms of a bidentate ligand, so three en ligands give coordination number six
sum the metal-ion and ligand charges to write the overall charge outside the complex brackets

[Maximum number: 1]

Titanium is a transition element in Period 4. It is commonly found as $\mathrm{TiO}_{2}$ in minerals.

Some reactions of $\mathrm{TiO}_{2}$ are shown in Fig. 3.1.

The anion, acac $^{-}$ , is a bidentate ligand.

Fig. 3.1

The titanium ions in $\mathrm{TiF}_{6}{ }^{2-}$ and $\mathrm{Ti}(\mathrm{acac})_{2} \mathrm{Cl}_{2}$ have a coordination number of 6 . State what is meant by coordination number.

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28.2.6—Coordination number and complex formula question 1