Which type of intermolecular force is primarily responsible for the attraction between two NH3 molecules?

• A. London dispersion forces
• B. Dipole-dipole interactions only
• C. Ionic bonding
• D. Hydrogen bonding

Answer: (D)

Verified step by step guidance

1. Identify the molecular structure of NH3 (ammonia). NH3 has a nitrogen atom bonded to three hydrogen atoms, and nitrogen is highly electronegative.
2. Recognize that because nitrogen is highly electronegative and bonded to hydrogen, the N-H bonds are polar, creating a significant dipole moment in the molecule.
3. Understand that hydrogen bonding is a special type of dipole-dipole interaction that occurs when hydrogen is directly bonded to highly electronegative atoms like nitrogen, oxygen, or fluorine.
4. Compare the types of intermolecular forces: London dispersion forces are weak and present in all molecules, dipole-dipole interactions occur between polar molecules, and ionic bonding involves attraction between ions, which is not the case here.
5. Conclude that the primary intermolecular force between NH3 molecules is hydrogen bonding due to the presence of N-H bonds and the lone pair on nitrogen that can interact with hydrogen atoms of neighboring molecules.