Copper forms the hydrated complex, [ extCu( extH2 extO)6]2+. (i) Give the name of the complex ion and draw its shape. (ii) Give the formula of the complex ion formed when a solution of EDTA is added t

Here are the solutions to the questions:

4. (b) Copper forms the hydrated complex, $[\text{Cu}(\text{H}_2\text{O})_6]^{2+}$

• (i) Give the name of the complex ion and draw its shape:

  • Name: $\boxed{\text{Hexaaquacopper(II) ion}}$
  • Shape: $\boxed{\text{Octahedral}}$ (A drawing would show a central Cu atom with six $\text{H}_2\text{O}$ ligands arranged at the vertices of an octahedron, with the overall $2+$ charge outside square brackets.)

• (ii) Give the formula of the complex ion formed when a solution of EDTA is added to a solution of $[\text{Cu}(\text{H}_2\text{O})_6]^{2+}$ EDTA is a hexadentate ligand, meaning it can form six coordinate bonds to a central metal ion. It will replace all six water ligands.

  • Formula: $\boxed{[\text{Cu}(\text{EDTA})]^{2-}}$

• (iii) Using the s p d notation, write the electronic configuration of copper in the complex ion. In the complex ion $[\text{Cu}(\text{H}_2\text{O})_6]^{2+}$, copper is in the +2 oxidation state ($\text{Cu}^{2+}$).

  • Atomic number of Copper (Cu) is 29.
  • Electronic configuration of neutral Cu: $1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10} 4s^1$.
  • To form $\text{Cu}^{2+}$, two electrons are removed: first from the $4s$ orbital, then from the $3d$ orbital.
  • Electronic configuration of $\text{Cu}^{2+}$: $\boxed{1s^2 2s^2 2p^6 3s^2 3p^6 3d^9}$

4. (c) Carbon, silicon, germanium, tin and lead are elements of Group IV (14) of the Periodic Table.

• (i) State the variation in structure of the elements carbon to lead. The elements of Group IV show a transition from giant covalent structures to giant metallic structures down the group. Carbon (diamond/graphite), silicon, and germanium have giant covalent structures. Tin and lead have giant metallic structures.

• (ii) Give the name or formula of a chloride of Group IV element that is

  • A: covalent and decomposes readily at room temperature and pressure (r.t.p.).

    • Name: $\boxed{\text{Lead(IV) chloride}}$
    • Formula: $\boxed{\text{PbCl}_4}$ (Lead(IV) chloride is covalent but thermally unstable and decomposes readily at room temperature to $\text{PbCl}_2$ and $\text{Cl}_2$.)

  • B: strongly reducing.

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