KEY2CHEM

Structure of Molecular Solids

Molecular solids are composed of discrete nonmetal elements or compounds held together by relatively weak intermolecular forces. This is in contrast to a covalent network solid, where adjacent atoms or molecules are held together by strong covalent bonds.

Example 1.

Which statement about molecular solids is most correct?

A. Molecular solids are composed of ions.

B. Molecular solids are composed of nonmetals covalently bonded together.

C. Molecular solids are composed of nonmetals who are held together by weak intermolecular forces.

Solution

C. Molecular solids are composed of nonmetals who are held together by weak intermolecular forces.

Covalent network solids are compounds where the nonmetal atoms (in either elements or compounds) are held together by strong covalent bonds.

Example 2.

Molecular solids are composed of nonmetal elements or compounds held together by _____________ forces.

A. strong ionic

B. weak intermolecular

C. strong covalent

Solution

B. weak intermolecular

Molecular solids are composed of nonmetal elements or compounds held together by weak intermolecular forces.

Example 3.

Which solid is an example of a molecular solid?

A. $$\require{mhchem}\ce{CO2}$$

B. $$\require{mhchem}\ce{Cu}$$

C. $$\require{mhchem}\ce{NaCl}$$

Solution

A. $$\require{mhchem}\ce{CO2}$$

Dry ice (solid $$\require{mhchem}\ce{CO2}$$) is an example of a molecular solids, composed of molecules of $$\require{mhchem}\ce{CO2}$$ held together by weak intermolecular forces.