Which statement describes a simple covalent lattice?

Which statement describes a simple covalent lattice?

• A. Particles: Molecules; Forces: Van der Waals; Properties: Low melting point, not conductors.
• B. Particles: Ions; Forces: Ionic bonds; Properties: High melting point.
• C. Particles: Atoms; Forces: Covalent bonds; Properties: Very hard.
• D. Particles: Positive ions and delocalized electrons; Forces: Metallic bonding; Properties: Good conductors.

Answer: (A)

A simple covalent lattice is a molecular solid where the repeating units are discrete molecules, not atoms or ions, and the lattice is held together by weak intermolecular forces such as van der Waals forces. Inside each molecule, atoms are connected by strong covalent bonds, but those bonds do not extend across the lattice. This arrangement means the solid has a relatively low melting point because only the weak intermolecular attractions need to be overcome to separate the molecules. It also tends to be a poor conductor of electricity since there are no mobile charged particles—electrons are mostly localized within the covalent bonds of the molecules. This contrasts with ionic lattices, which are built from ions held by strong electrostatic attractions and typically have high melting points and conduct electricity when melted or dissolved. Covalent network lattices involve a continuous network of covalent bonds throughout the material, giving very high melting points and extreme hardness. Metallic lattices consist of a lattice of positive ions with a sea of delocalized electrons, which makes them good conductors of electricity.

A simple covalent lattice is a molecular solid where the repeating units are discrete molecules, not atoms or ions, and the lattice is held together by weak intermolecular forces such as van der Waals forces. Inside each molecule, atoms are connected by strong covalent bonds, but those bonds do not extend across the lattice. This arrangement means the solid has a relatively low melting point because only the weak intermolecular attractions need to be overcome to separate the molecules. It also tends to be a poor conductor of electricity since there are no mobile charged particles—electrons are mostly localized within the covalent bonds of the molecules.

This contrasts with ionic lattices, which are built from ions held by strong electrostatic attractions and typically have high melting points and conduct electricity when melted or dissolved. Covalent network lattices involve a continuous network of covalent bonds throughout the material, giving very high melting points and extreme hardness. Metallic lattices consist of a lattice of positive ions with a sea of delocalized electrons, which makes them good conductors of electricity.