Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

Which interaction is exemplified by the combination of hydrogen and water molecules?

1. Dipole-dipole interaction

2. Van der Waals force

3. Ionic interaction

4. Metallic attraction

The correct answer is: Dipole-dipole interaction

The interaction exemplified by the combination of hydrogen and water molecules is correctly identified as a dipole-dipole interaction. In water (H₂O), the molecule has a bent shape due to its polar covalent bonds, where oxygen has a partial negative charge and each hydrogen has a partial positive charge. This creates a dipole moment, leading to the attraction between the positive end of one water molecule and the negative end of another. Dipole-dipole interactions are characteristic of polar molecules and are stronger than Van der Waals forces but weaker than ionic and metallic bonds. This provides water with its unique properties, such as high surface tension and a higher boiling point than similar-sized nonpolar molecules. The molecular polarity in water leads to significant hydrogen bonding between the molecules, which is a specific type of dipole-dipole interaction, further emphasizing the role of these interactions in determining the behavior of water in various contexts.