Chemistry 9701 · AS & A Level · Group 17

Group 17 — practice question

Iodine belongs to Group $17$ in the Periodic Table.
(a(i))[1]

At room temperature, solid iodine has a lattice structure. Describe how the iodine molecules are arranged inside the solid.

(a(ii))[2]

List every force of attraction in solid iodine, and indicate which ones are overcome when solid iodine is heated to form iodine vapour.

(b(i))[1]

When iodine reacts with aluminium, a white solid, $\text{Al}_2\text{I}_6$, is formed. The diagram shows how the outer electrons are arranged in one molecule of $\text{Al}_2\text{I}_6$. How many co-ordinate (dative covalent) bonds are formed as a molecule of $\text{Al}_2\text{I}_6$ is built from its atoms?

(b(ii))[1]

Describe how co-ordinate (dative covalent) bonds are formed in this molecule.

(c(i))[2]

When hydrogen iodide reacts with concentrated sulfuric acid, hydrogen sulfide, sulfur, iodine and water are formed. Write an equation for this reaction. You may find oxidation numbers useful.

(c(ii))[2]

Explain, using oxidation numbers, why this reaction is a redox reaction.

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