Chemistry Regents Practice Test

Which of the following compounds contains ionic bonds?

1. H2O

2. NaCl

3. CH4

4. CO2

The correct answer is: NaCl

The compound being identified as containing ionic bonds is sodium chloride (NaCl). Ionic bonds are formed between metals and nonmetals when electrons are transferred from one atom to another, resulting in the formation of charged ions. In the case of NaCl, sodium (Na) is a metal that loses one electron to become a positively charged ion (Na⁺), while chlorine (Cl) is a nonmetal that gains that electron to become a negatively charged ion (Cl⁻). The electrostatic attraction between these oppositely charged ions creates a strong ionic bond, resulting in the formation of the compound NaCl. In contrast, the other compounds do not exhibit ionic bonding. For example, water (H₂O) involves covalent bonds where electrons are shared between hydrogen and oxygen atoms. Similarly, methane (CH₄) and carbon dioxide (CO₂) also consist of covalent bonds, where carbon shares electrons with hydrogen and oxygen, respectively.