Which statement describes metallic solids?

• A. Metal atoms held together by metallic bonds; high melting points; ranges from soft to very hard; good conductors of electricity.
• B. Ionic lattice with strong electrostatic attractions.
• C. Covalently bonded network with high hardness.
• D. Molecules bound by hydrogen bonds.

Answer: (A)

Metallic solids are held together by metallic bonds, where valence electrons are delocalized over the whole lattice and form a shared electron sea. This arrangement lets electrons move freely, so metals conduct electricity in the solid state and bonds are non-directional, which supports malleability and the ability of layers to slide past one another.

The strength and non-directionality of these bonds also explain why metallic solids span a wide range of hardness while typically resting at high melting points—the energy needed to break the cooperative bonding across the lattice is substantial, though it can vary with structure and composition, making some metals softer and others very hard.

In contrast, ionic lattices rely on strong electrostatic attractions between oppositely charged ions and tend to be brittle even if melting points are high; covalently bonded networks feature highly directional bonds that create extreme hardness and poor conductivity; and hydrogen-bonded molecular solids are held by comparatively weak hydrogen bonds, usually giving lower melting points.