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Which type of intermolecular attractions holds ammonia molecules together with other ammonia molecules?

User Lyda
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1 Answer

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  • Hydrogen bonds (strongest).
  • Dipole-dipole interactions (weaker than hydrogen bonds).

Step-by-step explanation

There are three major types of intermolecular attractions:

  • Hydrogen bonds,
  • Dipole-dipole interactions, and
  • London dispersion forces.

London dispersion forces exist between all molecules. It is the weakest among the three types of forces.

Dipole-dipole interactions exist between polar molecules. It is stronger than London dispersion forces.

Hydrogen bonds are attractions between

  • H atoms directly bonded to atoms of N, O, or F; and
  • Lone pairs of electrons on other molecules.

Hydrogen bonds is the strongest among the three types of forces.

Consider the structure of an ammonia
\text{NH}_3 molecule.

  • All three H atoms are bonded to an N atom.
  • There is one lone pair of electrons on the central N atom.
  • N-H bonds are highly polar.
  • The shape of the
    \text{NH}_3 molecule is pyramidal. As a result, dipoles from the three N-H bond remain not balanced. The molecule is overall polar.

As a result,
\text{NH}_3 molecules will form both hydrogen bonds and dipole-dipole interactions between them. There's also going to be London dispersion forces. Nonetheless, hydrogen bonds and dipole-dipole interactions will contribute to the majority of attractions between the molecules.

User Elector
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