Explain how an ionic bond is formed when sodium reacts with chlorine. Include in your answer the charges of the ions formed.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Sodium loses one electron from its outer shell, forming a Na⁺ ion. Chlorine gains one electron into its outer shell, forming a Cl⁻ ion. The Na⁺ and Cl⁻ ions are attracted by strong electrostatic forces, creating an ionic bond.
Examiner tips
- Use the word ‘lose’ for sodium and ‘gain’ for chlorine to show electron transfer. Mention the ion charges (Na⁺, Cl⁻). Explain the attraction as the bond formation. Keep it concise to fit the 4 marks.
Common mistakes
- Writing that sodium gains an electron or chlorine loses one.
- Omitting the ion charges or the electrostatic attraction.
Mark scheme (4 marks)
- The sodium atom loses one electron (from its outer shell)
- The chlorine atom gains one electron (into its outer shell)
- Sodium forms a positively charged ion (Na⁺) and chlorine forms a negatively charged ion (Cl⁻)
- An ionic bond is formed by the strong electrostatic forces of attraction between the oppositely charged ions
Key terms in this question
Related
- All AQA GCSE Chemistry (8462) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →