Which lattice type is characterized by a low melting point and is not a conductor?

Which lattice type is characterized by a low melting point and is not a conductor?

• A. Simple covalent lattice
• B. Ionic lattice
• C. Macro covalent lattice
• D. Metallic lattice

Answer: (A)

The key idea is how bonding and structure determine melting behavior and electrical conductivity. In a simple covalent lattice, distinct molecules are packed together and held by only weak intermolecular forces between them, while the strong covalent bonds exist inside each molecule. This means only a small amount of energy is needed to separate the molecules from each other, giving a low melting point. Since the solid is made of neutral molecules with localized electrons, there aren’t free ions or delocalized electrons to move and carry charge, so it does not conduct electricity in either phase. This contrasts with ionic lattices, where strong electrostatic forces between ions yield high melting points; ions become mobile when molten or dissolved, so conduction occurs then. Metallic lattices have a sea of delocalized electrons that move freely and carry charge in the solid, leading to good electrical conductivity and typically high melting points. Macro covalent (giant covalent) lattices, with a network of strong covalent bonds, also show high melting points and are generally non-conductive due to the absence of free charge carriers.

The key idea is how bonding and structure determine melting behavior and electrical conductivity. In a simple covalent lattice, distinct molecules are packed together and held by only weak intermolecular forces between them, while the strong covalent bonds exist inside each molecule. This means only a small amount of energy is needed to separate the molecules from each other, giving a low melting point. Since the solid is made of neutral molecules with localized electrons, there aren’t free ions or delocalized electrons to move and carry charge, so it does not conduct electricity in either phase.

This contrasts with ionic lattices, where strong electrostatic forces between ions yield high melting points; ions become mobile when molten or dissolved, so conduction occurs then. Metallic lattices have a sea of delocalized electrons that move freely and carry charge in the solid, leading to good electrical conductivity and typically high melting points. Macro covalent (giant covalent) lattices, with a network of strong covalent bonds, also show high melting points and are generally non-conductive due to the absence of free charge carriers.