What are molecular solids?

Molecular solids are one of the four major types of solids you need to know about in AP chemistry. The others are ionic, metallic, and covalent network solids. Watch a video on the 🎥 structure of solids for additional help.

The Basics ⚛️

• Molecular solids are made of discrete molecules held together by intermolecular forces, not by a continuous network of covalent bonds.
• Learn more through this study guide on Intramolecular Force and Potential Energy
• Take ice, for example.
• Sure, each individual molecule is held together by covalent bonds, but the actual solid is created by hydrogen bonds connecting the molecules to each other.

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Properties

• Intermolecular forces are weaker than ionic or covalent bonds, so molecular solids are relatively soft and flexible.
• This also means they tend to have low melting points.
• They do not conduct electricity because electrons are localized within individual molecules.
• Many polar molecular solids, such as sugar, are soluble in water because they can form favorable intermolecular interactions with water. However, solubility is not guaranteed for every polar molecular solid, so use intermolecular forces and the idea of "like dissolves like" to predict solubility.
• Keep in mind that the individual molecules don't break apart, only the intermolecular forces do!