International General Certificate of Secondary Education (IGCSE) Chemistry Practice Exam

What type of bond is formed between sodium and chlorine in sodium chloride?

1. Ionic bond

2. Covalent bond

3. Metallic bond

4. Hydrogen bond

The correct answer is: Ionic bond

Sodium chloride, commonly known as table salt, is formed through the transfer of electrons from sodium to chlorine, resulting in the formation of ions. Sodium, which is in Group 1 of the periodic table, has one valence electron that it readily loses, converting it into a positively charged ion (Na⁺). Chlorine, located in Group 17, has seven valence electrons and requires one more electron to attain a stable electronic configuration, thus it gains the electron lost by sodium, forming a negatively charged ion (Cl⁻). The electrostatic attraction between these oppositely charged ions creates an ionic bond. This type of bond is characterized by the strong forces of attraction that result from the transfer of electrons and the formation of ions. The properties of ionic compounds, such as high melting and boiling points, can be attributed to the strength of these ionic bonds. In contrast, covalent bonds involve the sharing of electrons, metallic bonds involve a sea of shared electrons among metal atoms, and hydrogen bonds are weak attractions that occur between polar molecules. Therefore, in the case of sodium chloride, the sodium and chlorine atoms bond via an ionic interaction.