A student is given three suggested formulae for the compound formed when element P, in Group 2, reacts with element Q, in Group 6. Each suggestion also shows the ions that the compound would contain.
| Suggestion | Formula | Ions shown |
|---|---|---|
| A | P2Q\mathrm{P_{2}Q}P2Q | P+\mathrm{P^{+}}P+ and Q2−\mathrm{Q^{2-}}Q2− |
| B | PQ\mathrm{PQ}PQ | P2+\mathrm{P^{2+}}P2+ and Q2−\mathrm{Q^{2-}}Q2− |
| C | PQ2\mathrm{PQ_{2}}PQ2 | P2+\mathrm{P^{2+}}P2+ and Q−\mathrm{Q^{-}}Q− |
Evaluate the three suggestions. In your answer, explain how atoms of P and Q form ions.
113 exam-style questions on OCR GCSE Chemistry 4.1 Predicting chemical reactions, covering 4.1.1 Properties and trends in Groups 1, 7 and 0, 4.1.2 Properties of the transition metals, 4.1.3 Reactivity predicted from position in the Periodic Table, and 4.1.4 Reactivity of metals and the reactivity series. Each one has a worked solution and a mark scheme showing where the marks go.