A simple molecular lattice is best described as:

• A. A 3D structure of molecules held together by weak intermolecular forces
• B. A lattice of ions arranged in a repeating array
• C. A 3D network of covalent bonds
• D. A metallic lattice with a sea of electrons

Answer: (A)

A simple molecular lattice is made of discrete neutral molecules arranged in a regular 3D pattern and held together by weak intermolecular forces such as van der Waals forces, dipole–dipole interactions, or hydrogen bonding. This is why the structure is best described as a 3D arrangement of molecules bound by these weak forces rather than by strong ionic bonds, covalent networks, or metallic bonding.

If you imagined the other options: a lattice of ions would be an ionic lattice with strong electrostatic attractions between positively and negatively charged ions; a 3D network of covalent bonds would be a giant covalent solid where atoms are all interconnected in a continuous network (like diamond); a metallic lattice with a sea of electrons involves delocalized electrons moving through a lattice of metal ions. The defining feature of a simple molecular lattice is the presence of separate molecules held together by comparatively weak intermolecular forces, not extended bonds throughout the structure.